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rocksdb/db/compaction/compaction_picker_level.cc

812 lines
31 KiB

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/compaction/compaction_picker_level.h"
#include <string>
#include <utility>
#include <vector>
#include "db/version_edit.h"
#include "logging/log_buffer.h"
#include "test_util/sync_point.h"
namespace ROCKSDB_NAMESPACE {
bool LevelCompactionPicker::NeedsCompaction(
const VersionStorageInfo* vstorage) const {
if (!vstorage->ExpiredTtlFiles().empty()) {
return true;
}
if (!vstorage->FilesMarkedForPeriodicCompaction().empty()) {
return true;
}
if (!vstorage->BottommostFilesMarkedForCompaction().empty()) {
return true;
}
if (!vstorage->FilesMarkedForCompaction().empty()) {
return true;
}
Make it possible to force the garbage collection of the oldest blob files (#8994) Summary: The current BlobDB garbage collection logic works by relocating the valid blobs from the oldest blob files as they are encountered during compaction, and cleaning up blob files once they contain nothing but garbage. However, with sufficiently skewed workloads, it is theoretically possible to end up in a situation when few or no compactions get scheduled for the SST files that contain references to the oldest blob files, which can lead to increased space amp due to the lack of GC. In order to efficiently handle such workloads, the patch adds a new BlobDB configuration option called `blob_garbage_collection_force_threshold`, which signals to BlobDB to schedule targeted compactions for the SST files that keep alive the oldest batch of blob files if the overall ratio of garbage in the given blob files meets the threshold *and* all the given blob files are eligible for GC based on `blob_garbage_collection_age_cutoff`. (For example, if the new option is set to 0.9, targeted compactions will get scheduled if the sum of garbage bytes meets or exceeds 90% of the sum of total bytes in the oldest blob files, assuming all affected blob files are below the age-based cutoff.) The net result of these targeted compactions is that the valid blobs in the oldest blob files are relocated and the oldest blob files themselves cleaned up (since *all* SST files that rely on them get compacted away). These targeted compactions are similar to periodic compactions in the sense that they force certain SST files that otherwise would not get picked up to undergo compaction and also in the sense that instead of merging files from multiple levels, they target a single file. (Note: such compactions might still include neighboring files from the same level due to the need of having a "clean cut" boundary but they never include any files from any other level.) This functionality is currently only supported with the leveled compaction style and is inactive by default (since the default value is set to 1.0, i.e. 100%). Pull Request resolved: https://github.com/facebook/rocksdb/pull/8994 Test Plan: Ran `make check` and tested using `db_bench` and the stress/crash tests. Reviewed By: riversand963 Differential Revision: D31489850 Pulled By: ltamasi fbshipit-source-id: 44057d511726a0e2a03c5d9313d7511b3f0c4eab
3 years ago
if (!vstorage->FilesMarkedForForcedBlobGC().empty()) {
return true;
}
for (int i = 0; i <= vstorage->MaxInputLevel(); i++) {
if (vstorage->CompactionScore(i) >= 1) {
return true;
}
}
return false;
}
namespace {
// A class to build a leveled compaction step-by-step.
class LevelCompactionBuilder {
public:
LevelCompactionBuilder(const std::string& cf_name,
VersionStorageInfo* vstorage,
Fix corruption with intra-L0 on ingested files (#5958) Summary: ## Problem Description Our process was abort when it call `CheckConsistency`. And the information in `stderr` show that "`L0 files seqno 3001491972 3004797440 vs. 3002875611 3004524421` ". Here are the causes of the accident I investigated. * RocksDB will call `CheckConsistency` whenever `MANIFEST` file is update. It will check sequence number interval of every file, except files which were ingested. * When one file is ingested into RocksDB, it will be assigned the value of global sequence number, and the minimum and maximum seqno of this file are equal, which are both equal to global sequence number. * `CheckConsistency` determines whether the file is ingested by whether the smallest and largest seqno of an sstable file are equal. * If IntraL0Compaction picks one sst which was ingested just now and compacted it into another sst, the `smallest_seqno` of this new file will be smaller than his `largest_seqno`. * If more than one ingested file was ingested before memtable schedule flush, and they all compact into one new sstable file by `IntraL0Compaction`. The sequence interval of this new file will be included in the interval of the memtable. So `CheckConsistency` will return a `Corruption`. * If a sstable was ingested after the memtable was schedule to flush, which would assign a larger seqno to it than memtable. Then the file was compacted with other files (these files were all flushed before the memtable) in L0 into one file. This compaction start before the flush job of memtable start, but completed after the flush job finish. So this new file produced by the compaction (we call it s1) would have a larger interval of sequence number than the file produced by flush (we call it s2). **But there was still some data in s1 written into RocksDB before the s2, so it's possible that some data in s2 was cover by old data in s1.** Of course, it would also make a `Corruption` because of overlap of seqno. There is the relationship of the files: > s1.smallest_seqno < s2.smallest_seqno < s2.largest_seqno < s1.largest_seqno So I skip pick sst file which was ingested in function `FindIntraL0Compaction ` ## Reason Here is my bug report: https://github.com/facebook/rocksdb/issues/5913 There are two situations that can cause the check to fail. ### First situation: - First we ingest five external sst into Rocksdb, and they happened to be ingested in L0. and there had been some data in memtable, which make the smallest sequence number of memtable is less than which of sst that we ingest. - If there had been one compaction job which compacted sst from L0 to L1, `LevelCompactionPicker` would trigger a `IntraL0Compaction` which would compact this five sst from L0 to L0. We call this sst A, which was merged from five ingested sst. - Then some data was put into memtable, and memtable was flushed to L0. We called this sst B. - RocksDB check consistency , and find the `smallest_seqno` of B is less than that of A and crash. Because A was merged from five sst, the smallest sequence number of it was less than the biggest sequece number of itself, so RocksDB could not tell if A was produce by ingested. ### Secondary situaion - First we have flushed many sst in L0, we call them [s1, s2, s3]. - There is an immutable memtable request to be flushed, but because flush thread is busy, so it has not been picked. we call it m1. And at the moment, one sst is ingested into L0. We call it s4. Because s4 is ingested after m1 became immutable memtable, so it has a larger log sequence number than m1. - m1 is flushed in L0. because it is small, this flush job finish quickly. we call it s5. - [s1, s2, s3, s4] are compacted into one sst to L0, by IntraL0Compaction. We call it s6. - compacted 4@0 files to L0 - When s6 is added into manifest, the corruption happened. because the largest sequence number of s6 is equal to s4, and they are both larger than that of s5. But because s1 is older than m1, so the smallest sequence number of s6 is smaller than that of s5. - s6.smallest_seqno < s5.smallest_seqno < s5.largest_seqno < s6.largest_seqno Pull Request resolved: https://github.com/facebook/rocksdb/pull/5958 Differential Revision: D18601316 fbshipit-source-id: 5fe54b3c9af52a2e1400728f565e895cde1c7267
5 years ago
SequenceNumber earliest_mem_seqno,
CompactionPicker* compaction_picker,
LogBuffer* log_buffer,
const MutableCFOptions& mutable_cf_options,
const ImmutableOptions& ioptions,
const MutableDBOptions& mutable_db_options)
: cf_name_(cf_name),
vstorage_(vstorage),
Fix corruption with intra-L0 on ingested files (#5958) Summary: ## Problem Description Our process was abort when it call `CheckConsistency`. And the information in `stderr` show that "`L0 files seqno 3001491972 3004797440 vs. 3002875611 3004524421` ". Here are the causes of the accident I investigated. * RocksDB will call `CheckConsistency` whenever `MANIFEST` file is update. It will check sequence number interval of every file, except files which were ingested. * When one file is ingested into RocksDB, it will be assigned the value of global sequence number, and the minimum and maximum seqno of this file are equal, which are both equal to global sequence number. * `CheckConsistency` determines whether the file is ingested by whether the smallest and largest seqno of an sstable file are equal. * If IntraL0Compaction picks one sst which was ingested just now and compacted it into another sst, the `smallest_seqno` of this new file will be smaller than his `largest_seqno`. * If more than one ingested file was ingested before memtable schedule flush, and they all compact into one new sstable file by `IntraL0Compaction`. The sequence interval of this new file will be included in the interval of the memtable. So `CheckConsistency` will return a `Corruption`. * If a sstable was ingested after the memtable was schedule to flush, which would assign a larger seqno to it than memtable. Then the file was compacted with other files (these files were all flushed before the memtable) in L0 into one file. This compaction start before the flush job of memtable start, but completed after the flush job finish. So this new file produced by the compaction (we call it s1) would have a larger interval of sequence number than the file produced by flush (we call it s2). **But there was still some data in s1 written into RocksDB before the s2, so it's possible that some data in s2 was cover by old data in s1.** Of course, it would also make a `Corruption` because of overlap of seqno. There is the relationship of the files: > s1.smallest_seqno < s2.smallest_seqno < s2.largest_seqno < s1.largest_seqno So I skip pick sst file which was ingested in function `FindIntraL0Compaction ` ## Reason Here is my bug report: https://github.com/facebook/rocksdb/issues/5913 There are two situations that can cause the check to fail. ### First situation: - First we ingest five external sst into Rocksdb, and they happened to be ingested in L0. and there had been some data in memtable, which make the smallest sequence number of memtable is less than which of sst that we ingest. - If there had been one compaction job which compacted sst from L0 to L1, `LevelCompactionPicker` would trigger a `IntraL0Compaction` which would compact this five sst from L0 to L0. We call this sst A, which was merged from five ingested sst. - Then some data was put into memtable, and memtable was flushed to L0. We called this sst B. - RocksDB check consistency , and find the `smallest_seqno` of B is less than that of A and crash. Because A was merged from five sst, the smallest sequence number of it was less than the biggest sequece number of itself, so RocksDB could not tell if A was produce by ingested. ### Secondary situaion - First we have flushed many sst in L0, we call them [s1, s2, s3]. - There is an immutable memtable request to be flushed, but because flush thread is busy, so it has not been picked. we call it m1. And at the moment, one sst is ingested into L0. We call it s4. Because s4 is ingested after m1 became immutable memtable, so it has a larger log sequence number than m1. - m1 is flushed in L0. because it is small, this flush job finish quickly. we call it s5. - [s1, s2, s3, s4] are compacted into one sst to L0, by IntraL0Compaction. We call it s6. - compacted 4@0 files to L0 - When s6 is added into manifest, the corruption happened. because the largest sequence number of s6 is equal to s4, and they are both larger than that of s5. But because s1 is older than m1, so the smallest sequence number of s6 is smaller than that of s5. - s6.smallest_seqno < s5.smallest_seqno < s5.largest_seqno < s6.largest_seqno Pull Request resolved: https://github.com/facebook/rocksdb/pull/5958 Differential Revision: D18601316 fbshipit-source-id: 5fe54b3c9af52a2e1400728f565e895cde1c7267
5 years ago
earliest_mem_seqno_(earliest_mem_seqno),
compaction_picker_(compaction_picker),
log_buffer_(log_buffer),
mutable_cf_options_(mutable_cf_options),
ioptions_(ioptions),
mutable_db_options_(mutable_db_options) {}
// Pick and return a compaction.
Compaction* PickCompaction();
// Pick the initial files to compact to the next level. (or together
// in Intra-L0 compactions)
void SetupInitialFiles();
// If the initial files are from L0 level, pick other L0
// files if needed.
bool SetupOtherL0FilesIfNeeded();
Support subcmpct using reserved resources for round-robin priority (#10341) Summary: Earlier implementation of round-robin priority can only pick one file at a time and disallows parallel compactions within the same level. In this PR, round-robin compaction policy will expand towards more input files with respecting some additional constraints, which are summarized as follows: * Constraint 1: We can only pick consecutive files - Constraint 1a: When a file is being compacted (or some input files are being compacted after expanding), we cannot choose it and have to stop choosing more files - Constraint 1b: When we reach the last file (with the largest keys), we cannot choose more files (the next file will be the first one with small keys) * Constraint 2: We should ensure the total compaction bytes (including the overlapped files from the next level) is no more than `mutable_cf_options_.max_compaction_bytes` * Constraint 3: We try our best to pick as many files as possible so that the post-compaction level size can be just less than `MaxBytesForLevel(start_level_)` * Constraint 4: If trivial move is allowed, we reuse the logic of `TryNonL0TrivialMove()` instead of expanding files with Constraint 3 More details can be found in `LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion()`. The above optimization accelerates the process of moving the compaction cursor, in which the write-amp can be further reduced. While a large compaction may lead to high write stall, we break this large compaction into several subcompactions **regardless of** the `max_subcompactions` limit. The number of subcompactions for round-robin compaction priority is determined through the following steps: * Step 1: Initialized against `max_output_file_limit`, the number of input files in the start level, and also the range size limit `ranges.size()` * Step 2: Call `AcquireSubcompactionResources()`when max subcompactions is not sufficient, but we may or may not obtain desired resources, additional number of resources is stored in `extra_num_subcompaction_threads_reserved_`). Subcompaction limit is changed and update `num_planned_subcompactions` with `GetSubcompactionLimit()` * Step 3: Call `ShrinkSubcompactionResources()` to ensure extra resources can be released (extra resources may exist for round-robin compaction when the number of actual number of subcompactions is less than the number of planned subcompactions) More details can be found in `CompactionJob::AcquireSubcompactionResources()`,`CompactionJob::ShrinkSubcompactionResources()`, and `CompactionJob::ReleaseSubcompactionResources()`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10341 Test Plan: Add `CompactionPriMultipleFilesRoundRobin[1-3]` unit test in `compaction_picker_test.cc` and `RoundRobinSubcompactionsAgainstResources.SubcompactionsUsingResources/[0-4]`, `RoundRobinSubcompactionsAgainstPressureToken.PressureTokenTest/[0-1]` in `db_compaction_test.cc` Reviewed By: ajkr, hx235 Differential Revision: D37792644 Pulled By: littlepig2013 fbshipit-source-id: 7fecb7c4ffd97b34bbf6e3b760b2c35a772a0657
2 years ago
// Compaction with round-robin compaction priority allows more files to be
// picked to form a large compaction
void SetupOtherFilesWithRoundRobinExpansion();
// Based on initial files, setup other files need to be compacted
// in this compaction, accordingly.
bool SetupOtherInputsIfNeeded();
Compaction* GetCompaction();
// For the specfied level, pick a file that we want to compact.
// Returns false if there is no file to compact.
Support subcmpct using reserved resources for round-robin priority (#10341) Summary: Earlier implementation of round-robin priority can only pick one file at a time and disallows parallel compactions within the same level. In this PR, round-robin compaction policy will expand towards more input files with respecting some additional constraints, which are summarized as follows: * Constraint 1: We can only pick consecutive files - Constraint 1a: When a file is being compacted (or some input files are being compacted after expanding), we cannot choose it and have to stop choosing more files - Constraint 1b: When we reach the last file (with the largest keys), we cannot choose more files (the next file will be the first one with small keys) * Constraint 2: We should ensure the total compaction bytes (including the overlapped files from the next level) is no more than `mutable_cf_options_.max_compaction_bytes` * Constraint 3: We try our best to pick as many files as possible so that the post-compaction level size can be just less than `MaxBytesForLevel(start_level_)` * Constraint 4: If trivial move is allowed, we reuse the logic of `TryNonL0TrivialMove()` instead of expanding files with Constraint 3 More details can be found in `LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion()`. The above optimization accelerates the process of moving the compaction cursor, in which the write-amp can be further reduced. While a large compaction may lead to high write stall, we break this large compaction into several subcompactions **regardless of** the `max_subcompactions` limit. The number of subcompactions for round-robin compaction priority is determined through the following steps: * Step 1: Initialized against `max_output_file_limit`, the number of input files in the start level, and also the range size limit `ranges.size()` * Step 2: Call `AcquireSubcompactionResources()`when max subcompactions is not sufficient, but we may or may not obtain desired resources, additional number of resources is stored in `extra_num_subcompaction_threads_reserved_`). Subcompaction limit is changed and update `num_planned_subcompactions` with `GetSubcompactionLimit()` * Step 3: Call `ShrinkSubcompactionResources()` to ensure extra resources can be released (extra resources may exist for round-robin compaction when the number of actual number of subcompactions is less than the number of planned subcompactions) More details can be found in `CompactionJob::AcquireSubcompactionResources()`,`CompactionJob::ShrinkSubcompactionResources()`, and `CompactionJob::ReleaseSubcompactionResources()`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10341 Test Plan: Add `CompactionPriMultipleFilesRoundRobin[1-3]` unit test in `compaction_picker_test.cc` and `RoundRobinSubcompactionsAgainstResources.SubcompactionsUsingResources/[0-4]`, `RoundRobinSubcompactionsAgainstPressureToken.PressureTokenTest/[0-1]` in `db_compaction_test.cc` Reviewed By: ajkr, hx235 Differential Revision: D37792644 Pulled By: littlepig2013 fbshipit-source-id: 7fecb7c4ffd97b34bbf6e3b760b2c35a772a0657
2 years ago
// If it returns true, inputs->files.size() will be exactly one for
// all compaction priorities except round-robin. For round-robin,
// multiple consecutive files may be put into inputs->files.
// If level is 0 and there is already a compaction on that level, this
// function will return false.
bool PickFileToCompact();
// Return true if a L0 trivial move is picked up.
bool TryPickL0TrivialMove();
// For L0->L0, picks the longest span of files that aren't currently
// undergoing compaction for which work-per-deleted-file decreases. The span
// always starts from the newest L0 file.
//
// Intra-L0 compaction is independent of all other files, so it can be
// performed even when L0->base_level compactions are blocked.
//
// Returns true if `inputs` is populated with a span of files to be compacted;
// otherwise, returns false.
bool PickIntraL0Compaction();
// Return true if TrivialMove is extended. `start_index` is the index of
// the intiial file picked, which should already be in `start_level_inputs_`.
bool TryExtendNonL0TrivialMove(int start_index);
// Picks a file from level_files to compact.
// level_files is a vector of (level, file metadata) in ascending order of
// level. If compact_to_next_level is true, compact the file to the next
// level, otherwise, compact to the same level as the input file.
void PickFileToCompact(
const autovector<std::pair<int, FileMetaData*>>& level_files,
bool compact_to_next_level);
const std::string& cf_name_;
VersionStorageInfo* vstorage_;
Fix corruption with intra-L0 on ingested files (#5958) Summary: ## Problem Description Our process was abort when it call `CheckConsistency`. And the information in `stderr` show that "`L0 files seqno 3001491972 3004797440 vs. 3002875611 3004524421` ". Here are the causes of the accident I investigated. * RocksDB will call `CheckConsistency` whenever `MANIFEST` file is update. It will check sequence number interval of every file, except files which were ingested. * When one file is ingested into RocksDB, it will be assigned the value of global sequence number, and the minimum and maximum seqno of this file are equal, which are both equal to global sequence number. * `CheckConsistency` determines whether the file is ingested by whether the smallest and largest seqno of an sstable file are equal. * If IntraL0Compaction picks one sst which was ingested just now and compacted it into another sst, the `smallest_seqno` of this new file will be smaller than his `largest_seqno`. * If more than one ingested file was ingested before memtable schedule flush, and they all compact into one new sstable file by `IntraL0Compaction`. The sequence interval of this new file will be included in the interval of the memtable. So `CheckConsistency` will return a `Corruption`. * If a sstable was ingested after the memtable was schedule to flush, which would assign a larger seqno to it than memtable. Then the file was compacted with other files (these files were all flushed before the memtable) in L0 into one file. This compaction start before the flush job of memtable start, but completed after the flush job finish. So this new file produced by the compaction (we call it s1) would have a larger interval of sequence number than the file produced by flush (we call it s2). **But there was still some data in s1 written into RocksDB before the s2, so it's possible that some data in s2 was cover by old data in s1.** Of course, it would also make a `Corruption` because of overlap of seqno. There is the relationship of the files: > s1.smallest_seqno < s2.smallest_seqno < s2.largest_seqno < s1.largest_seqno So I skip pick sst file which was ingested in function `FindIntraL0Compaction ` ## Reason Here is my bug report: https://github.com/facebook/rocksdb/issues/5913 There are two situations that can cause the check to fail. ### First situation: - First we ingest five external sst into Rocksdb, and they happened to be ingested in L0. and there had been some data in memtable, which make the smallest sequence number of memtable is less than which of sst that we ingest. - If there had been one compaction job which compacted sst from L0 to L1, `LevelCompactionPicker` would trigger a `IntraL0Compaction` which would compact this five sst from L0 to L0. We call this sst A, which was merged from five ingested sst. - Then some data was put into memtable, and memtable was flushed to L0. We called this sst B. - RocksDB check consistency , and find the `smallest_seqno` of B is less than that of A and crash. Because A was merged from five sst, the smallest sequence number of it was less than the biggest sequece number of itself, so RocksDB could not tell if A was produce by ingested. ### Secondary situaion - First we have flushed many sst in L0, we call them [s1, s2, s3]. - There is an immutable memtable request to be flushed, but because flush thread is busy, so it has not been picked. we call it m1. And at the moment, one sst is ingested into L0. We call it s4. Because s4 is ingested after m1 became immutable memtable, so it has a larger log sequence number than m1. - m1 is flushed in L0. because it is small, this flush job finish quickly. we call it s5. - [s1, s2, s3, s4] are compacted into one sst to L0, by IntraL0Compaction. We call it s6. - compacted 4@0 files to L0 - When s6 is added into manifest, the corruption happened. because the largest sequence number of s6 is equal to s4, and they are both larger than that of s5. But because s1 is older than m1, so the smallest sequence number of s6 is smaller than that of s5. - s6.smallest_seqno < s5.smallest_seqno < s5.largest_seqno < s6.largest_seqno Pull Request resolved: https://github.com/facebook/rocksdb/pull/5958 Differential Revision: D18601316 fbshipit-source-id: 5fe54b3c9af52a2e1400728f565e895cde1c7267
5 years ago
SequenceNumber earliest_mem_seqno_;
CompactionPicker* compaction_picker_;
LogBuffer* log_buffer_;
int start_level_ = -1;
int output_level_ = -1;
int parent_index_ = -1;
int base_index_ = -1;
double start_level_score_ = 0;
bool is_manual_ = false;
bool is_l0_trivial_move_ = false;
CompactionInputFiles start_level_inputs_;
std::vector<CompactionInputFiles> compaction_inputs_;
CompactionInputFiles output_level_inputs_;
std::vector<FileMetaData*> grandparents_;
CompactionReason compaction_reason_ = CompactionReason::kUnknown;
const MutableCFOptions& mutable_cf_options_;
const ImmutableOptions& ioptions_;
const MutableDBOptions& mutable_db_options_;
// Pick a path ID to place a newly generated file, with its level
static uint32_t GetPathId(const ImmutableCFOptions& ioptions,
const MutableCFOptions& mutable_cf_options,
int level);
static const int kMinFilesForIntraL0Compaction = 4;
};
void LevelCompactionBuilder::PickFileToCompact(
const autovector<std::pair<int, FileMetaData*>>& level_files,
bool compact_to_next_level) {
for (auto& level_file : level_files) {
// If it's being compacted it has nothing to do here.
// If this assert() fails that means that some function marked some
// files as being_compacted, but didn't call ComputeCompactionScore()
assert(!level_file.second->being_compacted);
start_level_ = level_file.first;
if ((compact_to_next_level &&
start_level_ == vstorage_->num_non_empty_levels() - 1) ||
(start_level_ == 0 &&
!compaction_picker_->level0_compactions_in_progress()->empty())) {
continue;
}
if (compact_to_next_level) {
output_level_ =
(start_level_ == 0) ? vstorage_->base_level() : start_level_ + 1;
} else {
output_level_ = start_level_;
}
start_level_inputs_.files = {level_file.second};
start_level_inputs_.level = start_level_;
if (compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
&start_level_inputs_)) {
return;
}
}
start_level_inputs_.files.clear();
}
void LevelCompactionBuilder::SetupInitialFiles() {
// Find the compactions by size on all levels.
bool skipped_l0_to_base = false;
for (int i = 0; i < compaction_picker_->NumberLevels() - 1; i++) {
start_level_score_ = vstorage_->CompactionScore(i);
start_level_ = vstorage_->CompactionScoreLevel(i);
assert(i == 0 || start_level_score_ <= vstorage_->CompactionScore(i - 1));
if (start_level_score_ >= 1) {
if (skipped_l0_to_base && start_level_ == vstorage_->base_level()) {
// If L0->base_level compaction is pending, don't schedule further
// compaction from base level. Otherwise L0->base_level compaction
// may starve.
continue;
}
output_level_ =
(start_level_ == 0) ? vstorage_->base_level() : start_level_ + 1;
if (PickFileToCompact()) {
// found the compaction!
if (start_level_ == 0) {
// L0 score = `num L0 files` / `level0_file_num_compaction_trigger`
compaction_reason_ = CompactionReason::kLevelL0FilesNum;
} else {
// L1+ score = `Level files size` / `MaxBytesForLevel`
compaction_reason_ = CompactionReason::kLevelMaxLevelSize;
}
break;
} else {
// didn't find the compaction, clear the inputs
start_level_inputs_.clear();
if (start_level_ == 0) {
skipped_l0_to_base = true;
// L0->base_level may be blocked due to ongoing L0->base_level
// compactions. It may also be blocked by an ongoing compaction from
// base_level downwards.
//
// In these cases, to reduce L0 file count and thus reduce likelihood
// of write stalls, we can attempt compacting a span of files within
// L0.
if (PickIntraL0Compaction()) {
output_level_ = 0;
compaction_reason_ = CompactionReason::kLevelL0FilesNum;
break;
}
}
}
} else {
// Compaction scores are sorted in descending order, no further scores
// will be >= 1.
break;
}
}
if (!start_level_inputs_.empty()) {
return;
}
// if we didn't find a compaction, check if there are any files marked for
// compaction
parent_index_ = base_index_ = -1;
compaction_picker_->PickFilesMarkedForCompaction(
cf_name_, vstorage_, &start_level_, &output_level_, &start_level_inputs_);
if (!start_level_inputs_.empty()) {
compaction_reason_ = CompactionReason::kFilesMarkedForCompaction;
return;
}
// Bottommost Files Compaction on deleting tombstones
PickFileToCompact(vstorage_->BottommostFilesMarkedForCompaction(), false);
if (!start_level_inputs_.empty()) {
compaction_reason_ = CompactionReason::kBottommostFiles;
return;
}
// TTL Compaction
PickFileToCompact(vstorage_->ExpiredTtlFiles(), true);
if (!start_level_inputs_.empty()) {
compaction_reason_ = CompactionReason::kTtl;
return;
}
// Periodic Compaction
PickFileToCompact(vstorage_->FilesMarkedForPeriodicCompaction(), false);
if (!start_level_inputs_.empty()) {
compaction_reason_ = CompactionReason::kPeriodicCompaction;
return;
}
Make it possible to force the garbage collection of the oldest blob files (#8994) Summary: The current BlobDB garbage collection logic works by relocating the valid blobs from the oldest blob files as they are encountered during compaction, and cleaning up blob files once they contain nothing but garbage. However, with sufficiently skewed workloads, it is theoretically possible to end up in a situation when few or no compactions get scheduled for the SST files that contain references to the oldest blob files, which can lead to increased space amp due to the lack of GC. In order to efficiently handle such workloads, the patch adds a new BlobDB configuration option called `blob_garbage_collection_force_threshold`, which signals to BlobDB to schedule targeted compactions for the SST files that keep alive the oldest batch of blob files if the overall ratio of garbage in the given blob files meets the threshold *and* all the given blob files are eligible for GC based on `blob_garbage_collection_age_cutoff`. (For example, if the new option is set to 0.9, targeted compactions will get scheduled if the sum of garbage bytes meets or exceeds 90% of the sum of total bytes in the oldest blob files, assuming all affected blob files are below the age-based cutoff.) The net result of these targeted compactions is that the valid blobs in the oldest blob files are relocated and the oldest blob files themselves cleaned up (since *all* SST files that rely on them get compacted away). These targeted compactions are similar to periodic compactions in the sense that they force certain SST files that otherwise would not get picked up to undergo compaction and also in the sense that instead of merging files from multiple levels, they target a single file. (Note: such compactions might still include neighboring files from the same level due to the need of having a "clean cut" boundary but they never include any files from any other level.) This functionality is currently only supported with the leveled compaction style and is inactive by default (since the default value is set to 1.0, i.e. 100%). Pull Request resolved: https://github.com/facebook/rocksdb/pull/8994 Test Plan: Ran `make check` and tested using `db_bench` and the stress/crash tests. Reviewed By: riversand963 Differential Revision: D31489850 Pulled By: ltamasi fbshipit-source-id: 44057d511726a0e2a03c5d9313d7511b3f0c4eab
3 years ago
// Forced blob garbage collection
PickFileToCompact(vstorage_->FilesMarkedForForcedBlobGC(), false);
if (!start_level_inputs_.empty()) {
compaction_reason_ = CompactionReason::kForcedBlobGC;
return;
}
}
bool LevelCompactionBuilder::SetupOtherL0FilesIfNeeded() {
if (start_level_ == 0 && output_level_ != 0 && !is_l0_trivial_move_) {
return compaction_picker_->GetOverlappingL0Files(
vstorage_, &start_level_inputs_, output_level_, &parent_index_);
}
return true;
}
Support subcmpct using reserved resources for round-robin priority (#10341) Summary: Earlier implementation of round-robin priority can only pick one file at a time and disallows parallel compactions within the same level. In this PR, round-robin compaction policy will expand towards more input files with respecting some additional constraints, which are summarized as follows: * Constraint 1: We can only pick consecutive files - Constraint 1a: When a file is being compacted (or some input files are being compacted after expanding), we cannot choose it and have to stop choosing more files - Constraint 1b: When we reach the last file (with the largest keys), we cannot choose more files (the next file will be the first one with small keys) * Constraint 2: We should ensure the total compaction bytes (including the overlapped files from the next level) is no more than `mutable_cf_options_.max_compaction_bytes` * Constraint 3: We try our best to pick as many files as possible so that the post-compaction level size can be just less than `MaxBytesForLevel(start_level_)` * Constraint 4: If trivial move is allowed, we reuse the logic of `TryNonL0TrivialMove()` instead of expanding files with Constraint 3 More details can be found in `LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion()`. The above optimization accelerates the process of moving the compaction cursor, in which the write-amp can be further reduced. While a large compaction may lead to high write stall, we break this large compaction into several subcompactions **regardless of** the `max_subcompactions` limit. The number of subcompactions for round-robin compaction priority is determined through the following steps: * Step 1: Initialized against `max_output_file_limit`, the number of input files in the start level, and also the range size limit `ranges.size()` * Step 2: Call `AcquireSubcompactionResources()`when max subcompactions is not sufficient, but we may or may not obtain desired resources, additional number of resources is stored in `extra_num_subcompaction_threads_reserved_`). Subcompaction limit is changed and update `num_planned_subcompactions` with `GetSubcompactionLimit()` * Step 3: Call `ShrinkSubcompactionResources()` to ensure extra resources can be released (extra resources may exist for round-robin compaction when the number of actual number of subcompactions is less than the number of planned subcompactions) More details can be found in `CompactionJob::AcquireSubcompactionResources()`,`CompactionJob::ShrinkSubcompactionResources()`, and `CompactionJob::ReleaseSubcompactionResources()`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10341 Test Plan: Add `CompactionPriMultipleFilesRoundRobin[1-3]` unit test in `compaction_picker_test.cc` and `RoundRobinSubcompactionsAgainstResources.SubcompactionsUsingResources/[0-4]`, `RoundRobinSubcompactionsAgainstPressureToken.PressureTokenTest/[0-1]` in `db_compaction_test.cc` Reviewed By: ajkr, hx235 Differential Revision: D37792644 Pulled By: littlepig2013 fbshipit-source-id: 7fecb7c4ffd97b34bbf6e3b760b2c35a772a0657
2 years ago
void LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion() {
// We only expand when the start level is not L0 under round robin
assert(start_level_ >= 1);
// For round-robin compaction priority, we have 3 constraints when picking
// multiple files.
// Constraint 1: We can only pick consecutive files
// -> Constraint 1a: When a file is being compacted (or some input files
// are being compacted after expanding, we cannot
// choose it and have to stop choosing more files
// -> Constraint 1b: When we reach the last file (with largest keys), we
// cannot choose more files (the next file will be the
// first one)
// Constraint 2: We should ensure the total compaction bytes (including the
// overlapped files from the next level) is no more than
// mutable_cf_options_.max_compaction_bytes
// Constraint 3: We try our best to pick as many files as possible so that
// the post-compaction level size is less than
// MaxBytesForLevel(start_level_)
// Constraint 4: We do not expand if it is possible to apply a trivial move
// Constraint 5 (TODO): Try to pick minimal files to split into the target
// number of subcompactions
TEST_SYNC_POINT("LevelCompactionPicker::RoundRobin");
// Only expand the inputs when we have selected a file in start_level_inputs_
if (start_level_inputs_.size() == 0) return;
uint64_t start_lvl_bytes_no_compacting = 0;
uint64_t curr_bytes_to_compact = 0;
uint64_t start_lvl_max_bytes_to_compact = 0;
const std::vector<FileMetaData*>& level_files =
vstorage_->LevelFiles(start_level_);
// Constraint 3 (pre-calculate the ideal max bytes to compact)
for (auto f : level_files) {
if (!f->being_compacted) {
start_lvl_bytes_no_compacting += f->compensated_file_size;
}
}
if (start_lvl_bytes_no_compacting >
vstorage_->MaxBytesForLevel(start_level_)) {
start_lvl_max_bytes_to_compact = start_lvl_bytes_no_compacting -
vstorage_->MaxBytesForLevel(start_level_);
}
size_t start_index = vstorage_->FilesByCompactionPri(start_level_)[0];
InternalKey smallest, largest;
// Constraint 4 (No need to check again later)
compaction_picker_->GetRange(start_level_inputs_, &smallest, &largest);
CompactionInputFiles output_level_inputs;
output_level_inputs.level = output_level_;
vstorage_->GetOverlappingInputs(output_level_, &smallest, &largest,
&output_level_inputs.files);
if (output_level_inputs.empty()) {
if (TryExtendNonL0TrivialMove((int)start_index)) {
return;
}
}
// Constraint 3
if (start_level_inputs_[0]->compensated_file_size >=
start_lvl_max_bytes_to_compact) {
return;
}
CompactionInputFiles tmp_start_level_inputs;
tmp_start_level_inputs = start_level_inputs_;
// TODO (zichen): Future parallel round-robin may also need to update this
// Constraint 1b (only expand till the end)
for (size_t i = start_index + 1; i < level_files.size(); i++) {
auto* f = level_files[i];
if (f->being_compacted) {
// Constraint 1a
return;
}
tmp_start_level_inputs.files.push_back(f);
if (!compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
&tmp_start_level_inputs) ||
compaction_picker_->FilesRangeOverlapWithCompaction(
{tmp_start_level_inputs}, output_level_)) {
// Constraint 1a
tmp_start_level_inputs.clear();
return;
}
curr_bytes_to_compact = 0;
for (auto start_lvl_f : tmp_start_level_inputs.files) {
curr_bytes_to_compact += start_lvl_f->compensated_file_size;
}
// Check whether any output level files are locked
compaction_picker_->GetRange(tmp_start_level_inputs, &smallest, &largest);
vstorage_->GetOverlappingInputs(output_level_, &smallest, &largest,
&output_level_inputs.files);
if (!output_level_inputs.empty() &&
!compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
&output_level_inputs)) {
// Constraint 1a
tmp_start_level_inputs.clear();
return;
}
uint64_t start_lvl_curr_bytes_to_compact = curr_bytes_to_compact;
for (auto output_lvl_f : output_level_inputs.files) {
curr_bytes_to_compact += output_lvl_f->compensated_file_size;
}
if (curr_bytes_to_compact > mutable_cf_options_.max_compaction_bytes) {
// Constraint 2
tmp_start_level_inputs.clear();
return;
}
start_level_inputs_.files = tmp_start_level_inputs.files;
// Constraint 3
if (start_lvl_curr_bytes_to_compact > start_lvl_max_bytes_to_compact) {
return;
}
}
}
bool LevelCompactionBuilder::SetupOtherInputsIfNeeded() {
// Setup input files from output level. For output to L0, we only compact
// spans of files that do not interact with any pending compactions, so don't
// need to consider other levels.
if (output_level_ != 0) {
output_level_inputs_.level = output_level_;
Support subcmpct using reserved resources for round-robin priority (#10341) Summary: Earlier implementation of round-robin priority can only pick one file at a time and disallows parallel compactions within the same level. In this PR, round-robin compaction policy will expand towards more input files with respecting some additional constraints, which are summarized as follows: * Constraint 1: We can only pick consecutive files - Constraint 1a: When a file is being compacted (or some input files are being compacted after expanding), we cannot choose it and have to stop choosing more files - Constraint 1b: When we reach the last file (with the largest keys), we cannot choose more files (the next file will be the first one with small keys) * Constraint 2: We should ensure the total compaction bytes (including the overlapped files from the next level) is no more than `mutable_cf_options_.max_compaction_bytes` * Constraint 3: We try our best to pick as many files as possible so that the post-compaction level size can be just less than `MaxBytesForLevel(start_level_)` * Constraint 4: If trivial move is allowed, we reuse the logic of `TryNonL0TrivialMove()` instead of expanding files with Constraint 3 More details can be found in `LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion()`. The above optimization accelerates the process of moving the compaction cursor, in which the write-amp can be further reduced. While a large compaction may lead to high write stall, we break this large compaction into several subcompactions **regardless of** the `max_subcompactions` limit. The number of subcompactions for round-robin compaction priority is determined through the following steps: * Step 1: Initialized against `max_output_file_limit`, the number of input files in the start level, and also the range size limit `ranges.size()` * Step 2: Call `AcquireSubcompactionResources()`when max subcompactions is not sufficient, but we may or may not obtain desired resources, additional number of resources is stored in `extra_num_subcompaction_threads_reserved_`). Subcompaction limit is changed and update `num_planned_subcompactions` with `GetSubcompactionLimit()` * Step 3: Call `ShrinkSubcompactionResources()` to ensure extra resources can be released (extra resources may exist for round-robin compaction when the number of actual number of subcompactions is less than the number of planned subcompactions) More details can be found in `CompactionJob::AcquireSubcompactionResources()`,`CompactionJob::ShrinkSubcompactionResources()`, and `CompactionJob::ReleaseSubcompactionResources()`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10341 Test Plan: Add `CompactionPriMultipleFilesRoundRobin[1-3]` unit test in `compaction_picker_test.cc` and `RoundRobinSubcompactionsAgainstResources.SubcompactionsUsingResources/[0-4]`, `RoundRobinSubcompactionsAgainstPressureToken.PressureTokenTest/[0-1]` in `db_compaction_test.cc` Reviewed By: ajkr, hx235 Differential Revision: D37792644 Pulled By: littlepig2013 fbshipit-source-id: 7fecb7c4ffd97b34bbf6e3b760b2c35a772a0657
2 years ago
bool round_robin_expanding =
ioptions_.compaction_pri == kRoundRobin &&
compaction_reason_ == CompactionReason::kLevelMaxLevelSize;
if (round_robin_expanding) {
SetupOtherFilesWithRoundRobinExpansion();
}
if (!is_l0_trivial_move_ &&
!compaction_picker_->SetupOtherInputs(
cf_name_, mutable_cf_options_, vstorage_, &start_level_inputs_,
Support subcmpct using reserved resources for round-robin priority (#10341) Summary: Earlier implementation of round-robin priority can only pick one file at a time and disallows parallel compactions within the same level. In this PR, round-robin compaction policy will expand towards more input files with respecting some additional constraints, which are summarized as follows: * Constraint 1: We can only pick consecutive files - Constraint 1a: When a file is being compacted (or some input files are being compacted after expanding), we cannot choose it and have to stop choosing more files - Constraint 1b: When we reach the last file (with the largest keys), we cannot choose more files (the next file will be the first one with small keys) * Constraint 2: We should ensure the total compaction bytes (including the overlapped files from the next level) is no more than `mutable_cf_options_.max_compaction_bytes` * Constraint 3: We try our best to pick as many files as possible so that the post-compaction level size can be just less than `MaxBytesForLevel(start_level_)` * Constraint 4: If trivial move is allowed, we reuse the logic of `TryNonL0TrivialMove()` instead of expanding files with Constraint 3 More details can be found in `LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion()`. The above optimization accelerates the process of moving the compaction cursor, in which the write-amp can be further reduced. While a large compaction may lead to high write stall, we break this large compaction into several subcompactions **regardless of** the `max_subcompactions` limit. The number of subcompactions for round-robin compaction priority is determined through the following steps: * Step 1: Initialized against `max_output_file_limit`, the number of input files in the start level, and also the range size limit `ranges.size()` * Step 2: Call `AcquireSubcompactionResources()`when max subcompactions is not sufficient, but we may or may not obtain desired resources, additional number of resources is stored in `extra_num_subcompaction_threads_reserved_`). Subcompaction limit is changed and update `num_planned_subcompactions` with `GetSubcompactionLimit()` * Step 3: Call `ShrinkSubcompactionResources()` to ensure extra resources can be released (extra resources may exist for round-robin compaction when the number of actual number of subcompactions is less than the number of planned subcompactions) More details can be found in `CompactionJob::AcquireSubcompactionResources()`,`CompactionJob::ShrinkSubcompactionResources()`, and `CompactionJob::ReleaseSubcompactionResources()`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10341 Test Plan: Add `CompactionPriMultipleFilesRoundRobin[1-3]` unit test in `compaction_picker_test.cc` and `RoundRobinSubcompactionsAgainstResources.SubcompactionsUsingResources/[0-4]`, `RoundRobinSubcompactionsAgainstPressureToken.PressureTokenTest/[0-1]` in `db_compaction_test.cc` Reviewed By: ajkr, hx235 Differential Revision: D37792644 Pulled By: littlepig2013 fbshipit-source-id: 7fecb7c4ffd97b34bbf6e3b760b2c35a772a0657
2 years ago
&output_level_inputs_, &parent_index_, base_index_,
round_robin_expanding)) {
return false;
}
compaction_inputs_.push_back(start_level_inputs_);
if (!output_level_inputs_.empty()) {
compaction_inputs_.push_back(output_level_inputs_);
}
if (!is_l0_trivial_move_) {
// In some edge cases we could pick a compaction that will be compacting
// a key range that overlap with another running compaction, and both
// of them have the same output level. This could happen if
// (1) we are running a non-exclusive manual compaction
// (2) AddFile ingest a new file into the LSM tree
// We need to disallow this from happening.
if (compaction_picker_->FilesRangeOverlapWithCompaction(
compaction_inputs_, output_level_)) {
// This compaction output could potentially conflict with the output
// of a currently running compaction, we cannot run it.
return false;
}
compaction_picker_->GetGrandparents(vstorage_, start_level_inputs_,
output_level_inputs_, &grandparents_);
}
} else {
compaction_inputs_.push_back(start_level_inputs_);
}
return true;
}
Compaction* LevelCompactionBuilder::PickCompaction() {
// Pick up the first file to start compaction. It may have been extended
// to a clean cut.
SetupInitialFiles();
if (start_level_inputs_.empty()) {
return nullptr;
}
assert(start_level_ >= 0 && output_level_ >= 0);
// If it is a L0 -> base level compaction, we need to set up other L0
// files if needed.
if (!SetupOtherL0FilesIfNeeded()) {
return nullptr;
}
// Pick files in the output level and expand more files in the start level
// if needed.
if (!SetupOtherInputsIfNeeded()) {
return nullptr;
}
// Form a compaction object containing the files we picked.
Compaction* c = GetCompaction();
TEST_SYNC_POINT_CALLBACK("LevelCompactionPicker::PickCompaction:Return", c);
return c;
}
Compaction* LevelCompactionBuilder::GetCompaction() {
auto c = new Compaction(
vstorage_, ioptions_, mutable_cf_options_, mutable_db_options_,
std::move(compaction_inputs_), output_level_,
MaxFileSizeForLevel(mutable_cf_options_, output_level_,
ioptions_.compaction_style, vstorage_->base_level(),
ioptions_.level_compaction_dynamic_level_bytes),
mutable_cf_options_.max_compaction_bytes,
GetPathId(ioptions_, mutable_cf_options_, output_level_),
GetCompressionType(vstorage_, mutable_cf_options_, output_level_,
vstorage_->base_level()),
GetCompressionOptions(mutable_cf_options_, vstorage_, output_level_),
Temperature::kUnknown,
/* max_subcompactions */ 0, std::move(grandparents_), is_manual_,
/* trim_ts */ "", start_level_score_, false /* deletion_compaction */,
/* l0_files_might_overlap */ start_level_ == 0 && !is_l0_trivial_move_,
compaction_reason_);
// If it's level 0 compaction, make sure we don't execute any other level 0
// compactions in parallel
compaction_picker_->RegisterCompaction(c);
// Creating a compaction influences the compaction score because the score
// takes running compactions into account (by skipping files that are already
// being compacted). Since we just changed compaction score, we recalculate it
// here
vstorage_->ComputeCompactionScore(ioptions_, mutable_cf_options_);
return c;
}
/*
* Find the optimal path to place a file
* Given a level, finds the path where levels up to it will fit in levels
* up to and including this path
*/
uint32_t LevelCompactionBuilder::GetPathId(
const ImmutableCFOptions& ioptions,
const MutableCFOptions& mutable_cf_options, int level) {
uint32_t p = 0;
assert(!ioptions.cf_paths.empty());
// size remaining in the most recent path
uint64_t current_path_size = ioptions.cf_paths[0].target_size;
uint64_t level_size;
int cur_level = 0;
// max_bytes_for_level_base denotes L1 size.
// We estimate L0 size to be the same as L1.
level_size = mutable_cf_options.max_bytes_for_level_base;
// Last path is the fallback
while (p < ioptions.cf_paths.size() - 1) {
if (level_size <= current_path_size) {
if (cur_level == level) {
// Does desired level fit in this path?
return p;
} else {
current_path_size -= level_size;
if (cur_level > 0) {
if (ioptions.level_compaction_dynamic_level_bytes) {
// Currently, level_compaction_dynamic_level_bytes is ignored when
// multiple db paths are specified. https://github.com/facebook/
// rocksdb/blob/main/db/column_family.cc.
// Still, adding this check to avoid accidentally using
// max_bytes_for_level_multiplier_additional
level_size = static_cast<uint64_t>(
level_size * mutable_cf_options.max_bytes_for_level_multiplier);
} else {
level_size = static_cast<uint64_t>(
level_size * mutable_cf_options.max_bytes_for_level_multiplier *
mutable_cf_options.MaxBytesMultiplerAdditional(cur_level));
}
}
cur_level++;
continue;
}
}
p++;
current_path_size = ioptions.cf_paths[p].target_size;
}
return p;
}
bool LevelCompactionBuilder::TryPickL0TrivialMove() {
if (vstorage_->base_level() <= 0) {
return false;
}
if (start_level_ == 0 && mutable_cf_options_.compression_per_level.empty() &&
!vstorage_->LevelFiles(output_level_).empty() &&
ioptions_.db_paths.size() <= 1) {
// Try to pick trivial move from L0 to L1. We start from the oldest
// file. We keep expanding to newer files if it would form a
// trivial move.
// For now we don't support it with
// mutable_cf_options_.compression_per_level to prevent the logic
// of determining whether L0 can be trivial moved to the next level.
// We skip the case where output level is empty, since in this case, at
// least the oldest file would qualify for trivial move, and this would
// be a surprising behavior with few benefits.
// We search from the oldest file from the newest. In theory, there are
// files in the middle can form trivial move too, but it is probably
// uncommon and we ignore these cases for simplicity.
const std::vector<FileMetaData*>& level_files =
vstorage_->LevelFiles(start_level_);
InternalKey my_smallest, my_largest;
for (auto it = level_files.rbegin(); it != level_files.rend(); ++it) {
CompactionInputFiles output_level_inputs;
output_level_inputs.level = output_level_;
FileMetaData* file = *it;
if (it == level_files.rbegin()) {
my_smallest = file->smallest;
my_largest = file->largest;
} else {
if (compaction_picker_->icmp()->Compare(file->largest, my_smallest) <
0) {
my_smallest = file->smallest;
} else if (compaction_picker_->icmp()->Compare(file->smallest,
my_largest) > 0) {
my_largest = file->largest;
} else {
break;
}
}
vstorage_->GetOverlappingInputs(output_level_, &my_smallest, &my_largest,
&output_level_inputs.files);
if (output_level_inputs.empty()) {
assert(!file->being_compacted);
start_level_inputs_.files.push_back(file);
} else {
break;
}
}
}
if (!start_level_inputs_.empty()) {
// Sort files by key range. Not sure it's 100% necessary but it's cleaner
// to always keep files sorted by key the key ranges don't overlap.
std::sort(start_level_inputs_.files.begin(),
start_level_inputs_.files.end(),
[icmp = compaction_picker_->icmp()](FileMetaData* f1,
FileMetaData* f2) -> bool {
return (icmp->Compare(f1->smallest, f2->smallest) < 0);
});
is_l0_trivial_move_ = true;
return true;
}
return false;
}
bool LevelCompactionBuilder::TryExtendNonL0TrivialMove(int start_index) {
if (start_level_inputs_.size() == 1 &&
(ioptions_.db_paths.empty() || ioptions_.db_paths.size() == 1) &&
(mutable_cf_options_.compression_per_level.empty())) {
// Only file of `index`, and it is likely a trivial move. Try to
// expand if it is still a trivial move, but not beyond
// max_compaction_bytes or 4 files, so that we don't create too
// much compaction pressure for the next level.
// Ignore if there are more than one DB path, as it would be hard
// to predict whether it is a trivial move.
const std::vector<FileMetaData*>& level_files =
vstorage_->LevelFiles(start_level_);
const size_t kMaxMultiTrivialMove = 4;
FileMetaData* initial_file = start_level_inputs_.files[0];
size_t total_size = initial_file->fd.GetFileSize();
CompactionInputFiles output_level_inputs;
output_level_inputs.level = output_level_;
for (int i = start_index + 1;
i < static_cast<int>(level_files.size()) &&
start_level_inputs_.size() < kMaxMultiTrivialMove;
i++) {
FileMetaData* next_file = level_files[i];
if (next_file->being_compacted) {
break;
}
vstorage_->GetOverlappingInputs(output_level_, &(initial_file->smallest),
&(next_file->largest),
&output_level_inputs.files);
if (!output_level_inputs.empty()) {
break;
}
if (i < static_cast<int>(level_files.size()) - 1 &&
compaction_picker_->icmp()->user_comparator()->Compare(
next_file->largest.user_key(),
level_files[i + 1]->smallest.user_key()) == 0) {
// Not a clean up after adding the next file. Skip.
break;
}
total_size += next_file->fd.GetFileSize();
if (total_size > mutable_cf_options_.max_compaction_bytes) {
break;
}
start_level_inputs_.files.push_back(next_file);
}
return start_level_inputs_.size() > 1;
}
return false;
}
bool LevelCompactionBuilder::PickFileToCompact() {
// level 0 files are overlapping. So we cannot pick more
// than one concurrent compactions at this level. This
// could be made better by looking at key-ranges that are
// being compacted at level 0.
if (start_level_ == 0 &&
!compaction_picker_->level0_compactions_in_progress()->empty()) {
TEST_SYNC_POINT("LevelCompactionPicker::PickCompactionBySize:0");
return false;
}
start_level_inputs_.clear();
start_level_inputs_.level = start_level_;
assert(start_level_ >= 0);
if (TryPickL0TrivialMove()) {
return true;
}
const std::vector<FileMetaData*>& level_files =
vstorage_->LevelFiles(start_level_);
// Pick the file with the highest score in this level that is not already
// being compacted.
const std::vector<int>& file_scores =
vstorage_->FilesByCompactionPri(start_level_);
unsigned int cmp_idx;
for (cmp_idx = vstorage_->NextCompactionIndex(start_level_);
cmp_idx < file_scores.size(); cmp_idx++) {
int index = file_scores[cmp_idx];
auto* f = level_files[index];
// do not pick a file to compact if it is being compacted
// from n-1 level.
if (f->being_compacted) {
Add basic kRoundRobin compaction policy (#10107) Summary: Add `kRoundRobin` as a compaction priority. The implementation is as follows. - Define a cursor as the smallest Internal key in the successor of the selected file. Add `vector<InternalKey> compact_cursor_` into `VersionStorageInfo` where each element (`InternalKey`) in `compact_cursor_` represents a cursor. In round-robin compaction policy, we just need to select the first file (assuming files are sorted) and also has the smallest InternalKey larger than/equal to the cursor. After a file is chosen, we create a new `Fsize` vector which puts the selected file is placed at the first position in `temp`, the next cursor is then updated as the smallest InternalKey in successor of the selected file (the above logic is implemented in `SortFileByRoundRobin`). - After a compaction succeeds, typically `InstallCompactionResults()`, we choose the next cursor for the input level and save it to `edit`. When calling `LogAndApply`, we save the next cursor with its level into some local variable and finally apply the change to `vstorage` in `SaveTo` function. - Cursors are persist pair by pair (<level, InternalKey>) in `EncodeTo` so that they can be reconstructed when reopening. An empty cursor will not be encoded to MANIFEST Pull Request resolved: https://github.com/facebook/rocksdb/pull/10107 Test Plan: add unit test (`CompactionPriRoundRobin`) in `compaction_picker_test`, add `kRoundRobin` priority in `CompactionPriTest` from `db_compaction_test`, and add `PersistRoundRobinCompactCursor` in `db_compaction_test` Reviewed By: ajkr Differential Revision: D37316037 Pulled By: littlepig2013 fbshipit-source-id: 9f481748190ace416079139044e00df2968fb1ee
2 years ago
if (ioptions_.compaction_pri == kRoundRobin) {
// TODO(zichen): this file may be involved in one compaction from
// an upper level, cannot advance the cursor for round-robin policy.
// Currently, we do not pick any file to compact in this case. We
// should fix this later to ensure a compaction is picked but the
// cursor shall not be advanced.
return false;
}
continue;
}
start_level_inputs_.files.push_back(f);
if (!compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
&start_level_inputs_) ||
compaction_picker_->FilesRangeOverlapWithCompaction(
{start_level_inputs_}, output_level_)) {
// A locked (pending compaction) input-level file was pulled in due to
// user-key overlap.
start_level_inputs_.clear();
Add basic kRoundRobin compaction policy (#10107) Summary: Add `kRoundRobin` as a compaction priority. The implementation is as follows. - Define a cursor as the smallest Internal key in the successor of the selected file. Add `vector<InternalKey> compact_cursor_` into `VersionStorageInfo` where each element (`InternalKey`) in `compact_cursor_` represents a cursor. In round-robin compaction policy, we just need to select the first file (assuming files are sorted) and also has the smallest InternalKey larger than/equal to the cursor. After a file is chosen, we create a new `Fsize` vector which puts the selected file is placed at the first position in `temp`, the next cursor is then updated as the smallest InternalKey in successor of the selected file (the above logic is implemented in `SortFileByRoundRobin`). - After a compaction succeeds, typically `InstallCompactionResults()`, we choose the next cursor for the input level and save it to `edit`. When calling `LogAndApply`, we save the next cursor with its level into some local variable and finally apply the change to `vstorage` in `SaveTo` function. - Cursors are persist pair by pair (<level, InternalKey>) in `EncodeTo` so that they can be reconstructed when reopening. An empty cursor will not be encoded to MANIFEST Pull Request resolved: https://github.com/facebook/rocksdb/pull/10107 Test Plan: add unit test (`CompactionPriRoundRobin`) in `compaction_picker_test`, add `kRoundRobin` priority in `CompactionPriTest` from `db_compaction_test`, and add `PersistRoundRobinCompactCursor` in `db_compaction_test` Reviewed By: ajkr Differential Revision: D37316037 Pulled By: littlepig2013 fbshipit-source-id: 9f481748190ace416079139044e00df2968fb1ee
2 years ago
if (ioptions_.compaction_pri == kRoundRobin) {
return false;
}
continue;
}
// Now that input level is fully expanded, we check whether any output
// files are locked due to pending compaction.
//
// Note we rely on ExpandInputsToCleanCut() to tell us whether any output-
// level files are locked, not just the extra ones pulled in for user-key
// overlap.
InternalKey smallest, largest;
compaction_picker_->GetRange(start_level_inputs_, &smallest, &largest);
CompactionInputFiles output_level_inputs;
output_level_inputs.level = output_level_;
vstorage_->GetOverlappingInputs(output_level_, &smallest, &largest,
&output_level_inputs.files);
if (output_level_inputs.empty()) {
if (TryExtendNonL0TrivialMove(index)) {
break;
}
} else {
if (!compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
&output_level_inputs)) {
start_level_inputs_.clear();
if (ioptions_.compaction_pri == kRoundRobin) {
return false;
}
continue;
Add basic kRoundRobin compaction policy (#10107) Summary: Add `kRoundRobin` as a compaction priority. The implementation is as follows. - Define a cursor as the smallest Internal key in the successor of the selected file. Add `vector<InternalKey> compact_cursor_` into `VersionStorageInfo` where each element (`InternalKey`) in `compact_cursor_` represents a cursor. In round-robin compaction policy, we just need to select the first file (assuming files are sorted) and also has the smallest InternalKey larger than/equal to the cursor. After a file is chosen, we create a new `Fsize` vector which puts the selected file is placed at the first position in `temp`, the next cursor is then updated as the smallest InternalKey in successor of the selected file (the above logic is implemented in `SortFileByRoundRobin`). - After a compaction succeeds, typically `InstallCompactionResults()`, we choose the next cursor for the input level and save it to `edit`. When calling `LogAndApply`, we save the next cursor with its level into some local variable and finally apply the change to `vstorage` in `SaveTo` function. - Cursors are persist pair by pair (<level, InternalKey>) in `EncodeTo` so that they can be reconstructed when reopening. An empty cursor will not be encoded to MANIFEST Pull Request resolved: https://github.com/facebook/rocksdb/pull/10107 Test Plan: add unit test (`CompactionPriRoundRobin`) in `compaction_picker_test`, add `kRoundRobin` priority in `CompactionPriTest` from `db_compaction_test`, and add `PersistRoundRobinCompactCursor` in `db_compaction_test` Reviewed By: ajkr Differential Revision: D37316037 Pulled By: littlepig2013 fbshipit-source-id: 9f481748190ace416079139044e00df2968fb1ee
2 years ago
}
}
Support subcmpct using reserved resources for round-robin priority (#10341) Summary: Earlier implementation of round-robin priority can only pick one file at a time and disallows parallel compactions within the same level. In this PR, round-robin compaction policy will expand towards more input files with respecting some additional constraints, which are summarized as follows: * Constraint 1: We can only pick consecutive files - Constraint 1a: When a file is being compacted (or some input files are being compacted after expanding), we cannot choose it and have to stop choosing more files - Constraint 1b: When we reach the last file (with the largest keys), we cannot choose more files (the next file will be the first one with small keys) * Constraint 2: We should ensure the total compaction bytes (including the overlapped files from the next level) is no more than `mutable_cf_options_.max_compaction_bytes` * Constraint 3: We try our best to pick as many files as possible so that the post-compaction level size can be just less than `MaxBytesForLevel(start_level_)` * Constraint 4: If trivial move is allowed, we reuse the logic of `TryNonL0TrivialMove()` instead of expanding files with Constraint 3 More details can be found in `LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion()`. The above optimization accelerates the process of moving the compaction cursor, in which the write-amp can be further reduced. While a large compaction may lead to high write stall, we break this large compaction into several subcompactions **regardless of** the `max_subcompactions` limit. The number of subcompactions for round-robin compaction priority is determined through the following steps: * Step 1: Initialized against `max_output_file_limit`, the number of input files in the start level, and also the range size limit `ranges.size()` * Step 2: Call `AcquireSubcompactionResources()`when max subcompactions is not sufficient, but we may or may not obtain desired resources, additional number of resources is stored in `extra_num_subcompaction_threads_reserved_`). Subcompaction limit is changed and update `num_planned_subcompactions` with `GetSubcompactionLimit()` * Step 3: Call `ShrinkSubcompactionResources()` to ensure extra resources can be released (extra resources may exist for round-robin compaction when the number of actual number of subcompactions is less than the number of planned subcompactions) More details can be found in `CompactionJob::AcquireSubcompactionResources()`,`CompactionJob::ShrinkSubcompactionResources()`, and `CompactionJob::ReleaseSubcompactionResources()`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10341 Test Plan: Add `CompactionPriMultipleFilesRoundRobin[1-3]` unit test in `compaction_picker_test.cc` and `RoundRobinSubcompactionsAgainstResources.SubcompactionsUsingResources/[0-4]`, `RoundRobinSubcompactionsAgainstPressureToken.PressureTokenTest/[0-1]` in `db_compaction_test.cc` Reviewed By: ajkr, hx235 Differential Revision: D37792644 Pulled By: littlepig2013 fbshipit-source-id: 7fecb7c4ffd97b34bbf6e3b760b2c35a772a0657
2 years ago
base_index_ = index;
break;
}
// store where to start the iteration in the next call to PickCompaction
Add basic kRoundRobin compaction policy (#10107) Summary: Add `kRoundRobin` as a compaction priority. The implementation is as follows. - Define a cursor as the smallest Internal key in the successor of the selected file. Add `vector<InternalKey> compact_cursor_` into `VersionStorageInfo` where each element (`InternalKey`) in `compact_cursor_` represents a cursor. In round-robin compaction policy, we just need to select the first file (assuming files are sorted) and also has the smallest InternalKey larger than/equal to the cursor. After a file is chosen, we create a new `Fsize` vector which puts the selected file is placed at the first position in `temp`, the next cursor is then updated as the smallest InternalKey in successor of the selected file (the above logic is implemented in `SortFileByRoundRobin`). - After a compaction succeeds, typically `InstallCompactionResults()`, we choose the next cursor for the input level and save it to `edit`. When calling `LogAndApply`, we save the next cursor with its level into some local variable and finally apply the change to `vstorage` in `SaveTo` function. - Cursors are persist pair by pair (<level, InternalKey>) in `EncodeTo` so that they can be reconstructed when reopening. An empty cursor will not be encoded to MANIFEST Pull Request resolved: https://github.com/facebook/rocksdb/pull/10107 Test Plan: add unit test (`CompactionPriRoundRobin`) in `compaction_picker_test`, add `kRoundRobin` priority in `CompactionPriTest` from `db_compaction_test`, and add `PersistRoundRobinCompactCursor` in `db_compaction_test` Reviewed By: ajkr Differential Revision: D37316037 Pulled By: littlepig2013 fbshipit-source-id: 9f481748190ace416079139044e00df2968fb1ee
2 years ago
if (ioptions_.compaction_pri != kRoundRobin) {
vstorage_->SetNextCompactionIndex(start_level_, cmp_idx);
}
return start_level_inputs_.size() > 0;
}
bool LevelCompactionBuilder::PickIntraL0Compaction() {
start_level_inputs_.clear();
const std::vector<FileMetaData*>& level_files =
vstorage_->LevelFiles(0 /* level */);
if (level_files.size() <
static_cast<size_t>(
mutable_cf_options_.level0_file_num_compaction_trigger + 2) ||
level_files[0]->being_compacted) {
// If L0 isn't accumulating much files beyond the regular trigger, don't
// resort to L0->L0 compaction yet.
return false;
}
Fix corruption with intra-L0 on ingested files (#5958) Summary: ## Problem Description Our process was abort when it call `CheckConsistency`. And the information in `stderr` show that "`L0 files seqno 3001491972 3004797440 vs. 3002875611 3004524421` ". Here are the causes of the accident I investigated. * RocksDB will call `CheckConsistency` whenever `MANIFEST` file is update. It will check sequence number interval of every file, except files which were ingested. * When one file is ingested into RocksDB, it will be assigned the value of global sequence number, and the minimum and maximum seqno of this file are equal, which are both equal to global sequence number. * `CheckConsistency` determines whether the file is ingested by whether the smallest and largest seqno of an sstable file are equal. * If IntraL0Compaction picks one sst which was ingested just now and compacted it into another sst, the `smallest_seqno` of this new file will be smaller than his `largest_seqno`. * If more than one ingested file was ingested before memtable schedule flush, and they all compact into one new sstable file by `IntraL0Compaction`. The sequence interval of this new file will be included in the interval of the memtable. So `CheckConsistency` will return a `Corruption`. * If a sstable was ingested after the memtable was schedule to flush, which would assign a larger seqno to it than memtable. Then the file was compacted with other files (these files were all flushed before the memtable) in L0 into one file. This compaction start before the flush job of memtable start, but completed after the flush job finish. So this new file produced by the compaction (we call it s1) would have a larger interval of sequence number than the file produced by flush (we call it s2). **But there was still some data in s1 written into RocksDB before the s2, so it's possible that some data in s2 was cover by old data in s1.** Of course, it would also make a `Corruption` because of overlap of seqno. There is the relationship of the files: > s1.smallest_seqno < s2.smallest_seqno < s2.largest_seqno < s1.largest_seqno So I skip pick sst file which was ingested in function `FindIntraL0Compaction ` ## Reason Here is my bug report: https://github.com/facebook/rocksdb/issues/5913 There are two situations that can cause the check to fail. ### First situation: - First we ingest five external sst into Rocksdb, and they happened to be ingested in L0. and there had been some data in memtable, which make the smallest sequence number of memtable is less than which of sst that we ingest. - If there had been one compaction job which compacted sst from L0 to L1, `LevelCompactionPicker` would trigger a `IntraL0Compaction` which would compact this five sst from L0 to L0. We call this sst A, which was merged from five ingested sst. - Then some data was put into memtable, and memtable was flushed to L0. We called this sst B. - RocksDB check consistency , and find the `smallest_seqno` of B is less than that of A and crash. Because A was merged from five sst, the smallest sequence number of it was less than the biggest sequece number of itself, so RocksDB could not tell if A was produce by ingested. ### Secondary situaion - First we have flushed many sst in L0, we call them [s1, s2, s3]. - There is an immutable memtable request to be flushed, but because flush thread is busy, so it has not been picked. we call it m1. And at the moment, one sst is ingested into L0. We call it s4. Because s4 is ingested after m1 became immutable memtable, so it has a larger log sequence number than m1. - m1 is flushed in L0. because it is small, this flush job finish quickly. we call it s5. - [s1, s2, s3, s4] are compacted into one sst to L0, by IntraL0Compaction. We call it s6. - compacted 4@0 files to L0 - When s6 is added into manifest, the corruption happened. because the largest sequence number of s6 is equal to s4, and they are both larger than that of s5. But because s1 is older than m1, so the smallest sequence number of s6 is smaller than that of s5. - s6.smallest_seqno < s5.smallest_seqno < s5.largest_seqno < s6.largest_seqno Pull Request resolved: https://github.com/facebook/rocksdb/pull/5958 Differential Revision: D18601316 fbshipit-source-id: 5fe54b3c9af52a2e1400728f565e895cde1c7267
5 years ago
return FindIntraL0Compaction(level_files, kMinFilesForIntraL0Compaction,
std::numeric_limits<uint64_t>::max(),
Fix corruption with intra-L0 on ingested files (#5958) Summary: ## Problem Description Our process was abort when it call `CheckConsistency`. And the information in `stderr` show that "`L0 files seqno 3001491972 3004797440 vs. 3002875611 3004524421` ". Here are the causes of the accident I investigated. * RocksDB will call `CheckConsistency` whenever `MANIFEST` file is update. It will check sequence number interval of every file, except files which were ingested. * When one file is ingested into RocksDB, it will be assigned the value of global sequence number, and the minimum and maximum seqno of this file are equal, which are both equal to global sequence number. * `CheckConsistency` determines whether the file is ingested by whether the smallest and largest seqno of an sstable file are equal. * If IntraL0Compaction picks one sst which was ingested just now and compacted it into another sst, the `smallest_seqno` of this new file will be smaller than his `largest_seqno`. * If more than one ingested file was ingested before memtable schedule flush, and they all compact into one new sstable file by `IntraL0Compaction`. The sequence interval of this new file will be included in the interval of the memtable. So `CheckConsistency` will return a `Corruption`. * If a sstable was ingested after the memtable was schedule to flush, which would assign a larger seqno to it than memtable. Then the file was compacted with other files (these files were all flushed before the memtable) in L0 into one file. This compaction start before the flush job of memtable start, but completed after the flush job finish. So this new file produced by the compaction (we call it s1) would have a larger interval of sequence number than the file produced by flush (we call it s2). **But there was still some data in s1 written into RocksDB before the s2, so it's possible that some data in s2 was cover by old data in s1.** Of course, it would also make a `Corruption` because of overlap of seqno. There is the relationship of the files: > s1.smallest_seqno < s2.smallest_seqno < s2.largest_seqno < s1.largest_seqno So I skip pick sst file which was ingested in function `FindIntraL0Compaction ` ## Reason Here is my bug report: https://github.com/facebook/rocksdb/issues/5913 There are two situations that can cause the check to fail. ### First situation: - First we ingest five external sst into Rocksdb, and they happened to be ingested in L0. and there had been some data in memtable, which make the smallest sequence number of memtable is less than which of sst that we ingest. - If there had been one compaction job which compacted sst from L0 to L1, `LevelCompactionPicker` would trigger a `IntraL0Compaction` which would compact this five sst from L0 to L0. We call this sst A, which was merged from five ingested sst. - Then some data was put into memtable, and memtable was flushed to L0. We called this sst B. - RocksDB check consistency , and find the `smallest_seqno` of B is less than that of A and crash. Because A was merged from five sst, the smallest sequence number of it was less than the biggest sequece number of itself, so RocksDB could not tell if A was produce by ingested. ### Secondary situaion - First we have flushed many sst in L0, we call them [s1, s2, s3]. - There is an immutable memtable request to be flushed, but because flush thread is busy, so it has not been picked. we call it m1. And at the moment, one sst is ingested into L0. We call it s4. Because s4 is ingested after m1 became immutable memtable, so it has a larger log sequence number than m1. - m1 is flushed in L0. because it is small, this flush job finish quickly. we call it s5. - [s1, s2, s3, s4] are compacted into one sst to L0, by IntraL0Compaction. We call it s6. - compacted 4@0 files to L0 - When s6 is added into manifest, the corruption happened. because the largest sequence number of s6 is equal to s4, and they are both larger than that of s5. But because s1 is older than m1, so the smallest sequence number of s6 is smaller than that of s5. - s6.smallest_seqno < s5.smallest_seqno < s5.largest_seqno < s6.largest_seqno Pull Request resolved: https://github.com/facebook/rocksdb/pull/5958 Differential Revision: D18601316 fbshipit-source-id: 5fe54b3c9af52a2e1400728f565e895cde1c7267
5 years ago
mutable_cf_options_.max_compaction_bytes,
&start_level_inputs_, earliest_mem_seqno_);
}
} // namespace
Compaction* LevelCompactionPicker::PickCompaction(
const std::string& cf_name, const MutableCFOptions& mutable_cf_options,
const MutableDBOptions& mutable_db_options, VersionStorageInfo* vstorage,
LogBuffer* log_buffer, SequenceNumber earliest_mem_seqno) {
Fix corruption with intra-L0 on ingested files (#5958) Summary: ## Problem Description Our process was abort when it call `CheckConsistency`. And the information in `stderr` show that "`L0 files seqno 3001491972 3004797440 vs. 3002875611 3004524421` ". Here are the causes of the accident I investigated. * RocksDB will call `CheckConsistency` whenever `MANIFEST` file is update. It will check sequence number interval of every file, except files which were ingested. * When one file is ingested into RocksDB, it will be assigned the value of global sequence number, and the minimum and maximum seqno of this file are equal, which are both equal to global sequence number. * `CheckConsistency` determines whether the file is ingested by whether the smallest and largest seqno of an sstable file are equal. * If IntraL0Compaction picks one sst which was ingested just now and compacted it into another sst, the `smallest_seqno` of this new file will be smaller than his `largest_seqno`. * If more than one ingested file was ingested before memtable schedule flush, and they all compact into one new sstable file by `IntraL0Compaction`. The sequence interval of this new file will be included in the interval of the memtable. So `CheckConsistency` will return a `Corruption`. * If a sstable was ingested after the memtable was schedule to flush, which would assign a larger seqno to it than memtable. Then the file was compacted with other files (these files were all flushed before the memtable) in L0 into one file. This compaction start before the flush job of memtable start, but completed after the flush job finish. So this new file produced by the compaction (we call it s1) would have a larger interval of sequence number than the file produced by flush (we call it s2). **But there was still some data in s1 written into RocksDB before the s2, so it's possible that some data in s2 was cover by old data in s1.** Of course, it would also make a `Corruption` because of overlap of seqno. There is the relationship of the files: > s1.smallest_seqno < s2.smallest_seqno < s2.largest_seqno < s1.largest_seqno So I skip pick sst file which was ingested in function `FindIntraL0Compaction ` ## Reason Here is my bug report: https://github.com/facebook/rocksdb/issues/5913 There are two situations that can cause the check to fail. ### First situation: - First we ingest five external sst into Rocksdb, and they happened to be ingested in L0. and there had been some data in memtable, which make the smallest sequence number of memtable is less than which of sst that we ingest. - If there had been one compaction job which compacted sst from L0 to L1, `LevelCompactionPicker` would trigger a `IntraL0Compaction` which would compact this five sst from L0 to L0. We call this sst A, which was merged from five ingested sst. - Then some data was put into memtable, and memtable was flushed to L0. We called this sst B. - RocksDB check consistency , and find the `smallest_seqno` of B is less than that of A and crash. Because A was merged from five sst, the smallest sequence number of it was less than the biggest sequece number of itself, so RocksDB could not tell if A was produce by ingested. ### Secondary situaion - First we have flushed many sst in L0, we call them [s1, s2, s3]. - There is an immutable memtable request to be flushed, but because flush thread is busy, so it has not been picked. we call it m1. And at the moment, one sst is ingested into L0. We call it s4. Because s4 is ingested after m1 became immutable memtable, so it has a larger log sequence number than m1. - m1 is flushed in L0. because it is small, this flush job finish quickly. we call it s5. - [s1, s2, s3, s4] are compacted into one sst to L0, by IntraL0Compaction. We call it s6. - compacted 4@0 files to L0 - When s6 is added into manifest, the corruption happened. because the largest sequence number of s6 is equal to s4, and they are both larger than that of s5. But because s1 is older than m1, so the smallest sequence number of s6 is smaller than that of s5. - s6.smallest_seqno < s5.smallest_seqno < s5.largest_seqno < s6.largest_seqno Pull Request resolved: https://github.com/facebook/rocksdb/pull/5958 Differential Revision: D18601316 fbshipit-source-id: 5fe54b3c9af52a2e1400728f565e895cde1c7267
5 years ago
LevelCompactionBuilder builder(cf_name, vstorage, earliest_mem_seqno, this,
log_buffer, mutable_cf_options, ioptions_,
mutable_db_options);
return builder.PickCompaction();
}
} // namespace ROCKSDB_NAMESPACE