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95 Commits (02f2b208649b77e066f414eaea0d777a986b1f88)
| Author | SHA1 | Message | Date |
|---|---|---|---|
Yanqin Jin
|
c93ba7db5d |
Revise LockWAL/UnlockWAL implementation (#11020)
Summary: RocksDB has two public APIs: `DB::LockWAL()`/`DB::UnlockWAL()`. The current implementation acquires and releases the internal `DBImpl::log_write_mutex_`. According to the comment on `DBImpl::log_write_mutex_`: https://github.com/facebook/rocksdb/blob/7.8.fb/db/db_impl/db_impl.h#L2287:L2288 > Note: to avoid dealock, if needed to acquire both log_write_mutex_ and mutex_, the order should be first mutex_ and then log_write_mutex_. This puts limitations on how applications can use the `LockWAL()` API. After `LockWAL()` returns ok, then application should not perform any operation that acquires `mutex_`. Currently, the use case of `LockWAL()` is MyRocks implementing the MySQL storage engine handlerton `lock_hton_log` interface. The operation that MyRocks performs after `LockWAL()` is `GetSortedWalFiless()` which not only acquires mutex_, but also `log_write_mutex_`. There are two issues: 1. Applications using these two APIs may hang if one thread calls `GetSortedWalFiles()` after calling `LockWAL()` because log_write_mutex is not recursive. 2. Two threads may dead lock due to lock order inversion. To fix these issues, we can modify the implementation of LockWAL so that it does not keep `log_write_mutex_` held until UnlockWAL. To achieve the goal of locking the WAL, we can instead manually inject a write stall so that all future writes will be stopped. Pull Request resolved: https://github.com/facebook/rocksdb/pull/11020 Test Plan: make check Reviewed By: ajkr Differential Revision: D41785203 Pulled By: riversand963 fbshipit-source-id: 5ccb7a9c6eb9a2c3fa80fd2c399cc2568b8f89ce |
2 years ago |
|
Yanqin Jin
|
7d26e4c5a3 |
Basic Support for Merge with user-defined timestamp (#10819)
Summary:
This PR implements the originally disabled `Merge()` APIs when user-defined timestamp is enabled.
Simplest usage:
```cpp
// assume string append merge op is used with '.' as delimiter.
// ts1 < ts2
db->Put(WriteOptions(), "key", ts1, "v0");
db->Merge(WriteOptions(), "key", ts2, "1");
ReadOptions ro;
ro.timestamp = &ts2;
db->Get(ro, "key", &value);
ASSERT_EQ("v0.1", value);
```
Some code comments are added for clarity.
Note: support for timestamp in `DB::GetMergeOperands()` will be done in a follow-up PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10819
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D40603195
Pulled By: riversand963
fbshipit-source-id: f96d6f183258f3392d80377025529f7660503013
|
2 years ago |
|
Qingping Wang
|
a45e6878f3 |
fix issue 10751 (#10765)
Summary: Fix https://github.com/facebook/rocksdb/issues/10751 where a stalled write could be blocked forever when DB shutdown. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10765 Reviewed By: ajkr Differential Revision: D40110069 Pulled By: ajkr fbshipit-source-id: 598c05777db9be85913a0a85e421b3295ecdff5e |
2 years ago |
|
Yanqin Jin
|
edda219fc3 |
Manual flush with `wait=false` should not stall when writes stopped (#10001)
Summary: When `FlushOptions::wait` is set to false, manual flush should not stall forever. If the database has already stopped writes, then the thread calling `DB::Flush()` with `FlushOptions::wait=false` should not enter the `DBImpl::write_thread_`. To prevent this, we should do a check at the beginning and return `TryAgain()` Resolves: https://github.com/facebook/rocksdb/issues/9892 Pull Request resolved: https://github.com/facebook/rocksdb/pull/10001 Reviewed By: siying Differential Revision: D36422303 Pulled By: siying fbshipit-source-id: 723bd3065e8edc4f17c82449d0d6b95a2381ac0a |
2 years ago |
|
Changyu Bi
|
9f2363f4c4 |
User-defined timestamp support for `DeleteRange()` (#10661)
Summary: Add user-defined timestamp support for range deletion. The new API is `DeleteRange(opt, cf, begin_key, end_key, ts)`. Most of the change is to update the comparator to compare without timestamp. Other than that, major changes are - internal range tombstone data structures (`FragmentedRangeTombstoneList`, `RangeTombstone`, etc.) to store timestamps. - Garbage collection of range tombstones and range tombstone covered keys during compaction. - Get()/MultiGet() to return the timestamp of a range tombstone when needed. - Get/Iterator with range tombstones bounded by readoptions.timestamp. - timestamp crash test now issues DeleteRange by default. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10661 Test Plan: - Added unit test: `make check` - Stress test: `python3 tools/db_crashtest.py --enable_ts whitebox --readpercent=57 --prefixpercent=4 --writepercent=25 -delpercent=5 --iterpercent=5 --delrangepercent=4` - Ran `db_bench` to measure regression when timestamp is not enabled. The tests are for write (with some range deletion) and iterate with DB fitting in memory: `./db_bench--benchmarks=fillrandom,seekrandom --writes_per_range_tombstone=200 --max_write_buffer_number=100 --min_write_buffer_number_to_merge=100 --writes=500000 --reads=500000 --seek_nexts=10 --disable_auto_compactions -disable_wal=true --max_num_range_tombstones=1000`. Did not see consistent regression in no timestamp case. | micros/op | fillrandom | seekrandom | | --- | --- | --- | |main| 2.58 |10.96| |PR 10661| 2.68 |10.63| Reviewed By: riversand963 Differential Revision: D39441192 Pulled By: cbi42 fbshipit-source-id: f05aca3c41605caf110daf0ff405919f300ddec2 |
2 years ago |
|
Hui Xiao
|
e484b81eee |
Sync dir containing CURRENT after RenameFile on CURRENT as much as possible (#10573)
Summary:
**Context:**
Below crash test revealed a bug that directory containing CURRENT file (short for `dir_contains_current_file` below) was not always get synced after a new CURRENT is created and being called with `RenameFile` as part of the creation.
This bug exposes a risk that such un-synced directory containing the updated CURRENT can’t survive a host crash (e.g, power loss) hence get corrupted. This then will be followed by a recovery from a corrupted CURRENT that we don't want.
The root-cause is that a nullptr `FSDirectory* dir_contains_current_file` sometimes gets passed-down to `SetCurrentFile()` hence in those case `dir_contains_current_file->FSDirectory::FsyncWithDirOptions()` will be skipped (which otherwise will internally call`Env/FS::SyncDic()` )
```
./db_stress --acquire_snapshot_one_in=10000 --adaptive_readahead=1 --allow_data_in_errors=True --avoid_unnecessary_blocking_io=0 --backup_max_size=104857600 --backup_one_in=100000 --batch_protection_bytes_per_key=8 --block_size=16384 --bloom_bits=134.8015470676662 --bottommost_compression_type=disable --cache_size=8388608 --checkpoint_one_in=1000000 --checksum_type=kCRC32c --clear_column_family_one_in=0 --compact_files_one_in=1000000 --compact_range_one_in=1000000 --compaction_pri=2 --compaction_ttl=100 --compression_max_dict_buffer_bytes=511 --compression_max_dict_bytes=16384 --compression_type=zstd --compression_use_zstd_dict_trainer=1 --compression_zstd_max_train_bytes=65536 --continuous_verification_interval=0 --data_block_index_type=0 --db=$db --db_write_buffer_size=1048576 --delpercent=5 --delrangepercent=0 --destroy_db_initially=0 --disable_wal=0 --enable_compaction_filter=0 --enable_pipelined_write=1 --expected_values_dir=$exp --fail_if_options_file_error=1 --file_checksum_impl=none --flush_one_in=1000000 --get_current_wal_file_one_in=0 --get_live_files_one_in=1000000 --get_property_one_in=1000000 --get_sorted_wal_files_one_in=0 --index_block_restart_interval=4 --ingest_external_file_one_in=0 --iterpercent=10 --key_len_percent_dist=1,30,69 --level_compaction_dynamic_level_bytes=True --mark_for_compaction_one_file_in=10 --max_background_compactions=20 --max_bytes_for_level_base=10485760 --max_key=10000 --max_key_len=3 --max_manifest_file_size=16384 --max_write_batch_group_size_bytes=64 --max_write_buffer_number=3 --max_write_buffer_size_to_maintain=0 --memtable_prefix_bloom_size_ratio=0.001 --memtable_protection_bytes_per_key=1 --memtable_whole_key_filtering=1 --mmap_read=1 --nooverwritepercent=1 --open_metadata_write_fault_one_in=0 --open_read_fault_one_in=0 --open_write_fault_one_in=0 --ops_per_thread=100000000 --optimize_filters_for_memory=1 --paranoid_file_checks=1 --partition_pinning=2 --pause_background_one_in=1000000 --periodic_compaction_seconds=0 --prefix_size=5 --prefixpercent=5 --prepopulate_block_cache=1 --progress_reports=0 --read_fault_one_in=1000 --readpercent=45 --recycle_log_file_num=0 --reopen=0 --ribbon_starting_level=999 --secondary_cache_fault_one_in=32 --secondary_cache_uri=compressed_secondary_cache://capacity=8388608 --set_options_one_in=10000 --snapshot_hold_ops=100000 --sst_file_manager_bytes_per_sec=0 --sst_file_manager_bytes_per_truncate=0 --subcompactions=3 --sync_fault_injection=1 --target_file_size_base=2097 --target_file_size_multiplier=2 --test_batches_snapshots=1 --top_level_index_pinning=1 --use_full_merge_v1=1 --use_merge=1 --value_size_mult=32 --verify_checksum=1 --verify_checksum_one_in=1000000 --verify_db_one_in=100000 --verify_sst_unique_id_in_manifest=1 --wal_bytes_per_sync=524288 --write_buffer_size=4194 --writepercent=35
```
```
stderr:
WARNING: prefix_size is non-zero but memtablerep != prefix_hash
db_stress: utilities/fault_injection_fs.cc:748: virtual rocksdb::IOStatus rocksdb::FaultInjectionTestFS::RenameFile(const std::string &, const std::string &, const rocksdb::IOOptions &, rocksdb::IODebugContext *): Assertion `tlist.find(tdn.second) == tlist.end()' failed.`
```
**Summary:**
The PR ensured the non-test path pass down a non-null dir containing CURRENT (which is by current RocksDB assumption just db_dir) by doing the following:
- Renamed `directory_to_fsync` as `dir_contains_current_file` in `SetCurrentFile()` to tighten the association between this directory and CURRENT file
- Changed `SetCurrentFile()` API to require `dir_contains_current_file` being passed-in, instead of making it by default nullptr.
- Because `SetCurrentFile()`'s `dir_contains_current_file` is passed down from `VersionSet::LogAndApply()` then `VersionSet::ProcessManifestWrites()` (i.e, think about this as a chain of 3 functions related to MANIFEST update), these 2 functions also got refactored to require `dir_contains_current_file`
- Updated the non-test-path callers of these 3 functions to obtain and pass in non-nullptr `dir_contains_current_file`, which by current assumption of RocksDB, is the `FSDirectory* db_dir`.
- `db_impl` path will obtain `DBImpl::directories_.getDbDir()` while others with no access to such `directories_` are obtained on the fly by creating such object `FileSystem::NewDirectory(..)` and manage it by unique pointers to ensure short life time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10573
Test Plan:
- `make check`
- Passed the repro db_stress command
- For future improvement, since we currently don't assert dir containing CURRENT to be non-nullptr due to https://github.com/facebook/rocksdb/pull/10573#pullrequestreview-1087698899, there is still chances that future developers mistakenly pass down nullptr dir containing CURRENT thus resulting skipped sync dir and cause the bug again. Therefore a smarter test (e.g, such as quoted from ajkr "(make) unsynced data loss to be dropping files corresponding to unsynced directory entries") is still needed.
Reviewed By: ajkr
Differential Revision: D39005886
Pulled By: hx235
fbshipit-source-id: 336fb9090d0cfa6ca3dd580db86268007dde7f5a
|
2 years ago |
|
Andrew Kryczka
|
91166012c8 |
Prevent a case of WriteBufferManager flush thrashing (#6364)
Summary: Previously, the flushes triggered by `WriteBufferManager` could affect the same CF repeatedly if it happens to get consecutive writes. Such flushes are not particularly useful for reducing memory usage since they switch nearly-empty memtables to immutable while they've just begun filling their first arena block. In fact they may not even reduce the mutable memory count if they involve replacing one mutable memtable containing one arena block with a new mutable memtable containing one arena block. Further, if such switches happen even a few times before a flush finishes, the immutable memtable limit will be reached and writes will stall. This PR adds a heuristic to not switch memtables to immutable for CFs that already have one or more immutable memtables awaiting flush. There is a memory usage regression if the user continues writing to the same CF, that DB does not have any CFs eligible for switching, flushes are not finishing, and the `WriteBufferManager` was constructed with `allow_stall=false`. Before, it would grow by switching nearly empty memtables until writes stall. Now, it would grow by filling memtables until writes stall. This feels like an acceptable behavior change because users who prefer to stall over violate the memory limit should be using `allow_stall=true`, which is unaffected by this PR. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6364 Test Plan: - Command: `rm -rf /dev/shm/dbbench/ && TEST_TMPDIR=/dev/shm ./db_bench -benchmarks=fillrandom -num_multi_db=8 -num_column_families=2 -write_buffer_size=4194304 -db_write_buffer_size=16777216 -compression_type=none -statistics=true -target_file_size_base=4194304 -max_bytes_for_level_base=16777216` - `rocksdb.db.write.stall` count before this PR: 175 - `rocksdb.db.write.stall` count after this PR: 0 Reviewed By: jay-zhuang Differential Revision: D20167197 Pulled By: ajkr fbshipit-source-id: 4a64064e9bc33d57c0a35f15547542d0191d0cb7 |
2 years ago |
|
sdong
|
911c0208b9 |
WritableFileWriter tries to skip operations after failure (#10489)
Summary: A flag in WritableFileWriter is introduced to remember error has happened. Subsequent operations will fail with an assertion. Those operations, except Close() are not supposed to be called anyway. This change will help catch bug in tests and stress tests and limit damage of a potential bug of continue writing to a file after a failure. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10489 Test Plan: Fix existing unit tests and watch crash tests for a while. Reviewed By: anand1976 Differential Revision: D38473277 fbshipit-source-id: 09aafb971e56cfd7f9ef92ad15b883f54acf1366 |
2 years ago |
|
Changyu Bi
|
9d77bf8f7b |
Fragment memtable range tombstone in the write path (#10380)
Summary: - Right now each read fragments the memtable range tombstones https://github.com/facebook/rocksdb/issues/4808. This PR explores the idea of fragmenting memtable range tombstones in the write path and reads can just read this cached fragmented tombstone without any fragmenting cost. This PR only does the caching for immutable memtable, and does so right before a memtable is added to an immutable memtable list. The fragmentation is done without holding mutex to minimize its performance impact. - db_bench is updated to print out the number of range deletions executed if there is any. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10380 Test Plan: - CI, added asserts in various places to check whether a fragmented range tombstone list should have been constructed. - Benchmark: as this PR only optimizes immutable memtable path, the number of writes in the benchmark is chosen such an immutable memtable is created and range tombstones are in that memtable. ``` single thread: ./db_bench --benchmarks=fillrandom,readrandom --writes_per_range_tombstone=1 --max_write_buffer_number=100 --min_write_buffer_number_to_merge=100 --writes=500000 --reads=100000 --max_num_range_tombstones=100 multi_thread ./db_bench --benchmarks=fillrandom,readrandom --writes_per_range_tombstone=1 --max_write_buffer_number=100 --min_write_buffer_number_to_merge=100 --writes=15000 --reads=20000 --threads=32 --max_num_range_tombstones=100 ``` Commit 99cdf16464a057ca44de2f747541dedf651bae9e is included in benchmark result. It was an earlier attempt where tombstones are fragmented for each write operation. Reader threads share it using a shared_ptr which would slow down multi-thread read performance as seen in benchmark results. Results are averaged over 5 runs. Single thread result: | Max # tombstones | main fillrandom micros/op | 99cdf16464a057ca44de2f747541dedf651bae9e | Post PR | main readrandom micros/op | 99cdf16464a057ca44de2f747541dedf651bae9e | Post PR | | ------------- | ------------- |------------- |------------- |------------- |------------- |------------- | | 0 |6.68 |6.57 |6.72 |4.72 |4.79 |4.54 | | 1 |6.67 |6.58 |6.62 |5.41 |4.74 |4.72 | | 10 |6.59 |6.5 |6.56 |7.83 |4.69 |4.59 | | 100 |6.62 |6.75 |6.58 |29.57 |5.04 |5.09 | | 1000 |6.54 |6.82 |6.61 |320.33 |5.22 |5.21 | 32-thread result: note that "Max # tombstones" is per thread. | Max # tombstones | main fillrandom micros/op | 99cdf16464a057ca44de2f747541dedf651bae9e | Post PR | main readrandom micros/op | 99cdf16464a057ca44de2f747541dedf651bae9e | Post PR | | ------------- | ------------- |------------- |------------- |------------- |------------- |------------- | | 0 |234.52 |260.25 |239.42 |5.06 |5.38 |5.09 | | 1 |236.46 |262.0 |231.1 |19.57 |22.14 |5.45 | | 10 |236.95 |263.84 |251.49 |151.73 |21.61 |5.73 | | 100 |268.16 |296.8 |280.13 |2308.52 |22.27 |6.57 | Reviewed By: ajkr Differential Revision: D37916564 Pulled By: cbi42 fbshipit-source-id: 05d6d2e16df26c374c57ddcca13a5bfe9d5b731e |
2 years ago |
|
Wallace
|
1e9bf25f61 |
Do not hold mutex when write keys if not necessary (#7516)
Summary: ## Problem Summary RocksDB will acquire the global mutex of db instance for every time when user calls `Write`. When RocksDB schedules a lot of compaction jobs, it will compete the mutex with write thread and it will hurt the write performance. ## Problem Solution: I want to use log_write_mutex to replace the global mutex in most case so that we do not acquire it in write-thread unless there is a write-stall event or a write-buffer-full event occur. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7516 Test Plan: 1. make check 2. CI 3. COMPILE_WITH_TSAN=1 make db_stress make crash_test make crash_test_with_multiops_wp_txn make crash_test_with_multiops_wc_txn make crash_test_with_atomic_flush Reviewed By: siying Differential Revision: D36908702 Pulled By: riversand963 fbshipit-source-id: 59b13881f4f5c0a58fd3ca79128a396d9cd98efe |
2 years ago |
|
Levi Tamasi
|
c73d2a9d18 |
Add API for writing wide-column entities (#10242)
Summary: The patch builds on https://github.com/facebook/rocksdb/pull/9915 and adds a new API called `PutEntity` that can be used to write a wide-column entity to the database. The new API is added to both `DB` and `WriteBatch`. Note that currently there is no way to retrieve these entities; more precisely, all read APIs (`Get`, `MultiGet`, and iterator) return `NotSupported` when they encounter a wide-column entity that is required to answer a query. Read-side support (as well as other missing functionality like `Merge`, compaction filter, and timestamp support) will be added in later PRs. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10242 Test Plan: `make check` Reviewed By: riversand963 Differential Revision: D37369748 Pulled By: ltamasi fbshipit-source-id: 7f5e412359ed7a400fd80b897dae5599dbcd685d |
3 years ago |
|
Andrew Kryczka
|
d5d8920f2c |
Fix race condition with WAL tracking and `FlushWAL(true /* sync */)` (#10185)
Summary: `FlushWAL(true /* sync */)` is used internally and for manual WAL sync. It had a bug when used together with `track_and_verify_wals_in_manifest` where the synced size tracked in MANIFEST was larger than the number of bytes actually synced. The bug could be repro'd almost immediately with the following crash test command: `python3 tools/db_crashtest.py blackbox --simple --write_buffer_size=524288 --max_bytes_for_level_base=2097152 --target_file_size_base=524288 --duration=3600 --interval=10 --sync_fault_injection=1 --disable_wal=0 --checkpoint_one_in=1000 --max_key=10000 --value_size_mult=33`. An example error message produced by the above command is shown below. The error sometimes arose from the checkpoint and other times arose from the main stress test DB. ``` Corruption: Size mismatch: WAL (log number: 119) in MANIFEST is 27938 bytes , but actually is 27859 bytes on disk. ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/10185 Test Plan: - repro unit test - the above crash test command no longer finds the error. It does find a different error after a while longer such as "Corruption: WAL file 481 required by manifest but not in directory list" Reviewed By: riversand963 Differential Revision: D37200993 Pulled By: ajkr fbshipit-source-id: 98e0071c1a89f4d009888512ed89f9219779ae5f |
3 years ago |
|
Andrew Kryczka
|
5d6005c780 |
Add WriteOptions::protection_bytes_per_key (#10037)
Summary: Added an option, `WriteOptions::protection_bytes_per_key`, that controls how many bytes per key we use for integrity protection in `WriteBatch`. It takes effect when `WriteBatch::GetProtectionBytesPerKey() == 0`. Currently the only supported value is eight. Invoking a user API with it set to any other nonzero value will result in `Status::NotSupported` returned to the user. There is also a bug fix for integrity protection with `inplace_callback`, where we forgot to take into account the possible change in varint length when calculating KV checksum for the final encoded buffer. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10037 Test Plan: - Manual - Set default value of `WriteOptions::protection_bytes_per_key` to eight and ran `make check -j24` - Enabled in MyShadow for 1+ week - Automated - Unit tests have a `WriteMode` that enables the integrity protection via `WriteOptions` - Crash test - in most cases, use `WriteOptions::protection_bytes_per_key` to enable integrity protection Reviewed By: cbi42 Differential Revision: D36614569 Pulled By: ajkr fbshipit-source-id: 8650087ceac9b61b560f1e5fafe5e1baf9c725fb |
3 years ago |
|
Changyu Bi
|
9882652b0e |
Verify write batch checksum before WAL (#10114)
Summary: Context: WriteBatch can have key-value checksums when it was created `with protection_bytes_per_key > 0`. This PR added checksum verification for write batches before they are written to WAL. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10114 Test Plan: - Added new unit tests to db_kv_checksum_test.cc: `make check -j32` - benchmark on performance regression: `./db_bench --benchmarks=fillrandom[-X20] -db=/dev/shm/test_rocksdb -write_batch_protection_bytes_per_key=8` - Pre-PR: ` fillrandom [AVG 20 runs] : 198875 (± 3006) ops/sec; 22.0 (± 0.3) MB/sec ` - Post-PR: ` fillrandom [AVG 20 runs] : 196487 (± 2279) ops/sec; 21.7 (± 0.3) MB/sec ` Mean regressed about 1% (198875 -> 196487 ops/sec). Reviewed By: ajkr Differential Revision: D36917464 Pulled By: cbi42 fbshipit-source-id: 29beb74edf65f04b1a890b4f650d873dc7ed790d |
3 years ago |
|
Yanqin Jin
|
1777e5f7e9 |
Snapshots with user-specified timestamps (#9879)
Summary: In RocksDB, keys are associated with (internal) sequence numbers which denote when the keys are written to the database. Sequence numbers in different RocksDB instances are unrelated, thus not comparable. It is nice if we can associate sequence numbers with their corresponding actual timestamps. One thing we can do is to support user-defined timestamp, which allows the applications to specify the format of custom timestamps and encode a timestamp with each key. More details can be found at https://github.com/facebook/rocksdb/wiki/User-defined-Timestamp-%28Experimental%29. This PR provides a different but complementary approach. We can associate rocksdb snapshots (defined in https://github.com/facebook/rocksdb/blob/7.2.fb/include/rocksdb/snapshot.h#L20) with **user-specified** timestamps. Since a snapshot is essentially an object representing a sequence number, this PR establishes a bi-directional mapping between sequence numbers and timestamps. In the past, snapshots are usually taken by readers. The current super-version is grabbed, and a `rocksdb::Snapshot` object is created with the last published sequence number of the super-version. You can see that the reader actually has no good idea of what timestamp to assign to this snapshot, because by the time the `GetSnapshot()` is called, an arbitrarily long period of time may have already elapsed since the last write, which is when the last published sequence number is written. This observation motivates the creation of "timestamped" snapshots on the write path. Currently, this functionality is exposed only to the layer of `TransactionDB`. Application can tell RocksDB to create a snapshot when a transaction commits, effectively associating the last sequence number with a timestamp. It is also assumed that application will ensure any two snapshots with timestamps should satisfy the following: ``` snapshot1.seq < snapshot2.seq iff. snapshot1.ts < snapshot2.ts ``` If the application can guarantee that when a reader takes a timestamped snapshot, there is no active writes going on in the database, then we also allow the user to use a new API `TransactionDB::CreateTimestampedSnapshot()` to create a snapshot with associated timestamp. Code example ```cpp // Create a timestamped snapshot when committing transaction. txn->SetCommitTimestamp(100); txn->SetSnapshotOnNextOperation(); txn->Commit(); // A wrapper API for convenience Status Transaction::CommitAndTryCreateSnapshot( std::shared_ptr<TransactionNotifier> notifier, TxnTimestamp ts, std::shared_ptr<const Snapshot>* ret); // Create a timestamped snapshot if caller guarantees no concurrent writes std::pair<Status, std::shared_ptr<const Snapshot>> snapshot = txn_db->CreateTimestampedSnapshot(100); ``` The snapshots created in this way will be managed by RocksDB with ref-counting and potentially shared with other readers. We provide the following APIs for readers to retrieve a snapshot given a timestamp. ```cpp // Return the timestamped snapshot correponding to given timestamp. If ts is // kMaxTxnTimestamp, then we return the latest timestamped snapshot if present. // Othersise, we return the snapshot whose timestamp is equal to `ts`. If no // such snapshot exists, then we return null. std::shared_ptr<const Snapshot> TransactionDB::GetTimestampedSnapshot(TxnTimestamp ts) const; // Return the latest timestamped snapshot if present. std::shared_ptr<const Snapshot> TransactionDB::GetLatestTimestampedSnapshot() const; ``` We also provide two additional APIs for stats collection and reporting purposes. ```cpp Status TransactionDB::GetAllTimestampedSnapshots( std::vector<std::shared_ptr<const Snapshot>>& snapshots) const; // Return timestamped snapshots whose timestamps fall in [ts_lb, ts_ub) and store them in `snapshots`. Status TransactionDB::GetTimestampedSnapshots( TxnTimestamp ts_lb, TxnTimestamp ts_ub, std::vector<std::shared_ptr<const Snapshot>>& snapshots) const; ``` To prevent the number of timestamped snapshots from growing infinitely, we provide the following API to release timestamped snapshots whose timestamps are older than or equal to a given threshold. ```cpp void TransactionDB::ReleaseTimestampedSnapshotsOlderThan(TxnTimestamp ts); ``` Before shutdown, RocksDB will release all timestamped snapshots. Comparison with user-defined timestamp and how they can be combined: User-defined timestamp persists every key with a timestamp, while timestamped snapshots maintain a volatile mapping between snapshots (sequence numbers) and timestamps. Different internal keys with the same user key but different timestamps will be treated as different by compaction, thus a newer version will not hide older versions (with smaller timestamps) unless they are eligible for garbage collection. In contrast, taking a timestamped snapshot at a certain sequence number and timestamp prevents all the keys visible in this snapshot from been dropped by compaction. Here, visible means (seq < snapshot and most recent). The timestamped snapshot supports the semantics of reading at an exact point in time. Timestamped snapshots can also be used with user-defined timestamp. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9879 Test Plan: ``` make check TEST_TMPDIR=/dev/shm make crash_test_with_txn ``` Reviewed By: siying Differential Revision: D35783919 Pulled By: riversand963 fbshipit-source-id: 586ad905e169189e19d3bfc0cb0177a7239d1bd4 |
3 years ago |
|
Yu Zhang
|
a101c9de60 |
Return "invalid argument" when read timestamp is too old (#10109)
Summary: With this change, when a given read timestamp is smaller than the column-family's full_history_ts_low, Get(), MultiGet() and iterators APIs will return Status::InValidArgument(). Test plan ``` $COMPILE_WITH_ASAN=1 make -j24 all $./db_with_timestamp_basic_test --gtest_filter=DBBasicTestWithTimestamp.UpdateFullHistoryTsLow $ make -j24 check ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/10109 Reviewed By: riversand963 Differential Revision: D36901126 Pulled By: jowlyzhang fbshipit-source-id: 255feb1a66195351f06c1d0e42acb1ff74527f86 |
3 years ago |
|
Jay Zhuang
|
5864900cf4 |
Get current LogFileNumberSize the same as log_writer (#10086)
Summary: `db_impl.alive_log_files_` is used to track the WAL size in `db_impl.logs_`. Get the `LogFileNumberSize` obj in `alive_log_files_` the same time as `log_writer` to keep them consistent. For this issue, it's not safe to do `deque::reverse_iterator::operator*` and `deque::pop_front()` concurrently, so remove the tail cache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10086 Test Plan: ``` # on Windows gtest-parallel ./db_test --gtest_filter=DBTest.FileCreationRandomFailure -r 1000 -w 100 ``` Reviewed By: riversand963 Differential Revision: D36822373 Pulled By: jay-zhuang fbshipit-source-id: 5e738051dfc7bcf6a15d85ba25e6365df6b6a6af |
3 years ago |
|
Yanqin Jin
|
7c8c803938 |
Remove unused variable `single_column_family_mode_` (#10078)
Summary: This variable is actually not being used for anything meaningful, thus remove it. This can make https://github.com/facebook/rocksdb/issues/7516 slightly simpler by reducing the amount of state that must be made lock-free. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10078 Test Plan: make check Reviewed By: ajkr Differential Revision: D36779817 Pulled By: riversand963 fbshipit-source-id: ffb0d9ad6149616917ae5e02bb28102cb90fc406 |
3 years ago |
|
Yanqin Jin
|
de9df6e818 |
Do not release and re-acquire dbmutex on memtable-switch if no listener (#9758)
Summary: There is no need to release-and-acquire immediately when no listener is registered. This is what we have been doing for `NotifyOnFlushBegin()`, `NotifyOnFlushCompleted()`, `NotifyOnCompactionBegin()`, `NotifyOnCompactionCompleted()`, and some other `NotifyOnXX` methods in event_helpers.cc. Do the same for `NotifyOnMemTableSealed ()`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9758 Test Plan: make check Reviewed By: jay-zhuang Differential Revision: D35159552 Pulled By: riversand963 fbshipit-source-id: 6e0aac50bd5c8f506d809b6638c33a7a28d1e87f |
3 years ago |
|
Yanqin Jin
|
29bec740f5 |
Return invalid argument if batch is null (#9744)
Summary: Originally, a corruption will be returned by `DBImpl::WriteImpl(batch...)` if batch is null. This is inaccurate since there is no data corruption. Return `Status::InvalidArgument()` instead. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9744 Test Plan: make check Reviewed By: ltamasi Differential Revision: D35086268 Pulled By: riversand963 fbshipit-source-id: 677397b007a53bc25210eac0178d49c9797b5951 |
3 years ago |
|
Yanqin Jin
|
b2aacaf923 |
Fix assertion error by doing comparison with mutex (#9717)
Summary: On CircleCI MacOS instances, we have been seeing the following assertion error: ``` Assertion failed: (alive_log_files_tail_ == alive_log_files_.rbegin()), function WriteToWAL, file /Users/distiller/project/db/db_impl/db_impl_write.cc, line 1213. Received signal 6 (Abort trap: 6) #0 0x1 https://github.com/facebook/rocksdb/issues/1 abort (in libsystem_c.dylib) + 120 https://github.com/facebook/rocksdb/issues/2 err (in libsystem_c.dylib) + 0 https://github.com/facebook/rocksdb/issues/3 rocksdb::DBImpl::WriteToWAL(rocksdb::WriteBatch const&, rocksdb::log::Writer*, unsigned long long*, unsigned long long*, rocksdb::Env::IOPriority, bool, bool) (in librocksdb.7.0.0.dylib) (db_impl_write.cc:1213) https://github.com/facebook/rocksdb/issues/4 rocksdb::DBImpl::WriteToWAL(rocksdb::WriteThread::WriteGroup const&, rocksdb::log::Writer*, unsigned long long*, bool, bool, unsigned long long) (in librocksdb.7.0.0.dylib) (db_impl_write.cc:1251) https://github.com/facebook/rocksdb/issues/5 rocksdb::DBImpl::WriteImpl(rocksdb::WriteOptions const&, rocksdb::WriteBatch*, rocksdb::WriteCallback*, unsigned long long*, unsigned long long, bool, unsigned long long*, unsigned long, rocksdb::PreReleaseCallback*) (in librocksdb.7.0.0.dylib) (db_impl_ rite.cc:421) https://github.com/facebook/rocksdb/issues/6 rocksdb::DBImpl::Write(rocksdb::WriteOptions const&, rocksdb::WriteBatch*) (in librocksdb.7.0.0.dylib) (db_impl_write.cc:109) https://github.com/facebook/rocksdb/issues/7 rocksdb::DB::Put(rocksdb::WriteOptions const&, rocksdb::ColumnFamilyHandle*, rocksdb::Slice const&, rocksdb::Slice const&, rocksdb::Slice const&) (in librocksdb.7.0.0.dylib) (db_impl_write.cc:2159) https://github.com/facebook/rocksdb/issues/8 rocksdb::DBImpl::Put(rocksdb::WriteOptions const&, rocksdb::ColumnFamilyHandle*, rocksdb::Slice const&, rocksdb::Slice const&, rocksdb::Slice const&) (in librocksdb.7.0.0.dylib) (db_impl_write.cc:37) https://github.com/facebook/rocksdb/issues/9 rocksdb::DB::Put(rocksdb::WriteOptions const&, rocksdb::Slice const&, rocksdb::Slice const&, rocksdb::Slice const&) (in librocksdb.7.0.0.dylib) (db.h:382) https://github.com/facebook/rocksdb/issues/10 rocksdb::DBBasicTestWithTimestampPrefixSeek_IterateWithPrefix_Test::TestBody() (in db_with_timestamp_basic_test) (db_with_timestamp_basic_test.cc:2926) https://github.com/facebook/rocksdb/issues/11 void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (in db_with_timestamp_basic_test) (gtest-all.cc:3899) https://github.com/facebook/rocksdb/issues/12 void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (in db_with_timestamp_basic_test) (gtest-all.cc:3935) https://github.com/facebook/rocksdb/issues/13 testing::Test::Run() (in db_with_timestamp_basic_test) (gtest-all.cc:3980) https://github.com/facebook/rocksdb/issues/14 testing::TestInfo::Run() (in db_with_timestamp_basic_test) (gtest-all.cc:4153) https://github.com/facebook/rocksdb/issues/15 testing::TestCase::Run() (in db_with_timestamp_basic_test) (gtest-all.cc:4266) https://github.com/facebook/rocksdb/issues/16 testing::internal::UnitTestImpl::RunAllTests() (in db_with_timestamp_basic_test) (gtest-all.cc:6632) https://github.com/facebook/rocksdb/issues/17 bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) (in db_with_timestamp_basic_test) (gtest-all.cc:3899) https://github.com/facebook/rocksdb/issues/18 bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) (in db_with_timestamp_basic_test) (gtest-all.cc:3935) https://github.com/facebook/rocksdb/issues/19 testing::UnitTest::Run() (in db_with_timestamp_basic_test) (gtest-all.cc:6242) https://github.com/facebook/rocksdb/issues/20 RUN_ALL_TESTS() (in db_with_timestamp_basic_test) (gtest.h:22110) https://github.com/facebook/rocksdb/issues/21 main (in db_with_timestamp_basic_test) (db_with_timestamp_basic_test.cc:3150) https://github.com/facebook/rocksdb/issues/22 start (in libdyld.dylib) + 1 ``` It's likely caused by concurrent, unprotected access to the deque, even though `back()` is never popped, and we are comparing `rbegin()` with a cached `riterator`. To be safe, do the comparison only if we have mutex. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9717 Test Plan: One example Ssh to one CircleCI MacOS instance. ``` gtest-parallel -r 1000 -w 8 ./db_test --gtest_filter=DBTest.FlushesInParallelWithCompactRange ``` Reviewed By: pdillinger Differential Revision: D34990696 Pulled By: riversand963 fbshipit-source-id: 62dd48ae6fedbda53d0a64d73de9b948b4c26eee |
3 years ago |
|
Yanqin Jin
|
6a76008369 |
Fix TSAN caused by calling `rend()` and `pop_front()`. (#9698)
Summary: PR9686 makes `WriteToWAL()` call `assert(...!=rend())` while not holding db mutex or log mutex. Another thread may concurrently call `pop_front()`, causing race condition. To fix, assert only if mutex is held. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9698 Test Plan: COMPILE_WITH_TSAN=1 make check Reviewed By: jay-zhuang Differential Revision: D34898535 Pulled By: riversand963 fbshipit-source-id: 1ddfa5bf1b6ae8d409cab6ff6e1b5321c6803da9 |
3 years ago |
|
Yanqin Jin
|
bbdaf63d0f |
Fix a TSAN-reported bug caused by concurrent accesss to std::deque (#9686)
Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/9686 According to https://www.cplusplus.com/reference/deque/deque/back/, " The container is accessed (neither the const nor the non-const versions modify the container). The last element is potentially accessed or modified by the caller. Concurrently accessing or modifying other elements is safe. " Also according to https://www.cplusplus.com/reference/deque/deque/pop_front/, " The container is modified. The first element is modified. Concurrently accessing or modifying other elements is safe (although see iterator validity above). " In RocksDB, we never pop the last element of `DBImpl::alive_log_files_`. We have been exploiting this fact and the above two properties when ensuring correctness when `DBImpl::alive_log_files_` may be accessed concurrently. Specifically, it can be accessed in the write path when db mutex is released. Sometimes, the log_mute_ is held. It can also be accessed in `FindObsoleteFiles()` when db mutex is always held. It can also be accessed during recovery when db mutex is also held. Given the fact that we never pop the last element of alive_log_files_, we currently do not acquire additional locks when accessing it in `WriteToWAL()` as follows ``` alive_log_files_.back().AddSize(log_entry.size()); ``` This is problematic. Check source code of deque.h ``` back() _GLIBCXX_NOEXCEPT { __glibcxx_requires_nonempty(); ... } pop_front() _GLIBCXX_NOEXCEPT { ... if (this->_M_impl._M_start._M_cur != this->_M_impl._M_start._M_last - 1) { ... ++this->_M_impl._M_start._M_cur; } ... } ``` `back()` will actually call `__glibcxx_requires_nonempty()` first. If `__glibcxx_requires_nonempty()` is enabled and not an empty macro, it will call `empty()` ``` bool empty() { return this->_M_impl._M_finish == this->_M_impl._M_start; } ``` You can see that it will access `this->_M_impl._M_start`, racing with `pop_front()`. Therefore, TSAN will actually catch the bug in this case. To be able to use TSAN on our library and unit tests, we should always coordinate concurrent accesses to STL containers properly. We need to pass information about db mutex and log mutex into `WriteToWAL()`, otherwise it's impossible to know which mutex to acquire inside the function. To fix this, we can catch the tail of `alive_log_files_` by reference, so that we do not have to call `back()` in `WriteToWAL()`. Reviewed By: pdillinger Differential Revision: D34780309 fbshipit-source-id: 1def9821f0c437f2736c6a26445d75890377889b |
3 years ago |
|
Yanqin Jin
|
3b6dc049f7 |
Support user-defined timestamps in write-committed txns (#9629)
Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/9629 Pessimistic transactions use pessimistic concurrency control, i.e. locking. Keys are locked upon first operation that writes the key or has the intention of writing. For example, `PessimisticTransaction::Put()`, `PessimisticTransaction::Delete()`, `PessimisticTransaction::SingleDelete()` will write to or delete a key, while `PessimisticTransaction::GetForUpdate()` is used by application to indicate to RocksDB that the transaction has the intention of performing write operation later in the same transaction. Pessimistic transactions support two-phase commit (2PC). A transaction can be `Prepared()`'ed and then `Commit()`. The prepare phase is similar to a promise: once `Prepare()` succeeds, the transaction has acquired the necessary resources to commit. The resources include locks, persistence of WAL, etc. Write-committed transaction is the default pessimistic transaction implementation. In RocksDB write-committed transaction, `Prepare()` will write data to the WAL as a prepare section. `Commit()` will write a commit marker to the WAL and then write data to the memtables. While writing to the memtables, different keys in the transaction's write batch will be assigned different sequence numbers in ascending order. Until commit/rollback, the transaction holds locks on the keys so that no other transaction can write to the same keys. Furthermore, the keys' sequence numbers represent the order in which they are committed and should be made visible. This is convenient for us to implement support for user-defined timestamps. Since column families with and without timestamps can co-exist in the same database, a transaction may or may not involve timestamps. Based on this observation, we add two optional members to each `PessimisticTransaction`, `read_timestamp_` and `commit_timestamp_`. If no key in the transaction's write batch has timestamp, then setting these two variables do not have any effect. For the rest of this commit, we discuss only the cases when these two variables are meaningful. read_timestamp_ is used mainly for validation, and should be set before first call to `GetForUpdate()`. Otherwise, the latter will return non-ok status. `GetForUpdate()` calls `TryLock()` that can verify if another transaction has written the same key since `read_timestamp_` till this call to `GetForUpdate()`. If another transaction has indeed written the same key, then validation fails, and RocksDB allows this transaction to refine `read_timestamp_` by increasing it. Note that a transaction can still use `Get()` with a different timestamp to read, but the result of the read should not be used to determine data that will be written later. commit_timestamp_ must be set after finishing writing and before transaction commit. This applies to both 2PC and non-2PC cases. In the case of 2PC, it's usually set after prepare phase succeeds. We currently require that the commit timestamp be chosen after all keys are locked. This means we disallow the `TransactionDB`-level APIs if user-defined timestamp is used by the transaction. Specifically, calling `PessimisticTransactionDB::Put()`, `PessimisticTransactionDB::Delete()`, `PessimisticTransactionDB::SingleDelete()`, etc. will return non-ok status because they specify timestamps before locking the keys. Users are also prompted to use the `Transaction` APIs when they receive the non-ok status. Reviewed By: ltamasi Differential Revision: D31822445 fbshipit-source-id: b82abf8e230216dc89cc519564a588224a88fd43 |
3 years ago |
|
Hui Xiao
|
ca0ef54f16 |
Rate-limit automatic WAL flush after each user write (#9607)
Summary: **Context:** WAL flush is currently not rate-limited by `Options::rate_limiter`. This PR is to provide rate-limiting to auto WAL flush, the one that automatically happen after each user write operation (i.e, `Options::manual_wal_flush == false`), by adding `WriteOptions::rate_limiter_options`. Note that we are NOT rate-limiting WAL flush that do NOT automatically happen after each user write, such as `Options::manual_wal_flush == true + manual FlushWAL()` (rate-limiting multiple WAL flushes), for the benefits of: - being consistent with [ReadOptions::rate_limiter_priority](https://github.com/facebook/rocksdb/blob/7.0.fb/include/rocksdb/options.h#L515) - being able to turn off some WAL flush's rate-limiting but not all (e.g, turn off specific the WAL flush of a critical user write like a service's heartbeat) `WriteOptions::rate_limiter_options` only accept `Env::IO_USER` and `Env::IO_TOTAL` currently due to an implementation constraint. - The constraint is that we currently queue parallel writes (including WAL writes) based on FIFO policy which does not factor rate limiter priority into this layer's scheduling. If we allow lower priorities such as `Env::IO_HIGH/MID/LOW` and such writes specified with lower priorities occurs before ones specified with higher priorities (even just by a tiny bit in arrival time), the former would have blocked the latter, leading to a "priority inversion" issue and contradictory to what we promise for rate-limiting priority. Therefore we only allow `Env::IO_USER` and `Env::IO_TOTAL` right now before improving that scheduling. A pre-requisite to this feature is to support operation-level rate limiting in `WritableFileWriter`, which is also included in this PR. **Summary:** - Renamed test suite `DBRateLimiterTest to DBRateLimiterOnReadTest` for adding a new test suite - Accept `rate_limiter_priority` in `WritableFileWriter`'s private and public write functions - Passed `WriteOptions::rate_limiter_options` to `WritableFileWriter` in the path of automatic WAL flush. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9607 Test Plan: - Added new unit test to verify existing flush/compaction rate-limiting does not break, since `DBTest, RateLimitingTest` is disabled and current db-level rate-limiting tests focus on read only (e.g, `db_rate_limiter_test`, `DBTest2, RateLimitedCompactionReads`). - Added new unit test `DBRateLimiterOnWriteWALTest, AutoWalFlush` - `strace -ftt -e trace=write ./db_bench -benchmarks=fillseq -db=/dev/shm/testdb -rate_limit_auto_wal_flush=1 -rate_limiter_bytes_per_sec=15 -rate_limiter_refill_period_us=1000000 -write_buffer_size=100000000 -disable_auto_compactions=1 -num=100` - verified that WAL flush(i.e, system-call _write_) were chunked into 15 bytes and each _write_ was roughly 1 second apart - verified the chunking disappeared when `-rate_limit_auto_wal_flush=0` - crash test: `python3 tools/db_crashtest.py blackbox --disable_wal=0 --rate_limit_auto_wal_flush=1 --rate_limiter_bytes_per_sec=10485760 --interval=10` killed as normal **Benchmarked on flush/compaction to ensure no performance regression:** - compaction with rate-limiting (see table 1, avg over 1280-run): pre-change: **915635 micros/op**; post-change: **907350 micros/op (improved by 0.106%)** ``` #!/bin/bash TEST_TMPDIR=/dev/shm/testdb START=1 NUM_DATA_ENTRY=8 N=10 rm -f compact_bmk_output.txt compact_bmk_output_2.txt dont_care_output.txt for i in $(eval echo "{$START..$NUM_DATA_ENTRY}") do NUM_RUN=$(($N*(2**($i-1)))) for j in $(eval echo "{$START..$NUM_RUN}") do ./db_bench --benchmarks=fillrandom -db=$TEST_TMPDIR -disable_auto_compactions=1 -write_buffer_size=6710886 > dont_care_output.txt && ./db_bench --benchmarks=compact -use_existing_db=1 -db=$TEST_TMPDIR -level0_file_num_compaction_trigger=1 -rate_limiter_bytes_per_sec=100000000 | egrep 'compact' done > compact_bmk_output.txt && awk -v NUM_RUN=$NUM_RUN '{sum+=$3;sum_sqrt+=$3^2}END{print sum/NUM_RUN, sqrt(sum_sqrt/NUM_RUN-(sum/NUM_RUN)^2)}' compact_bmk_output.txt >> compact_bmk_output_2.txt done ``` - compaction w/o rate-limiting (see table 2, avg over 640-run): pre-change: **822197 micros/op**; post-change: **823148 micros/op (regressed by 0.12%)** ``` Same as above script, except that -rate_limiter_bytes_per_sec=0 ``` - flush with rate-limiting (see table 3, avg over 320-run, run on the [patch]( |
3 years ago |
|
Yanqin Jin
|
3122cb4358 |
Revise APIs related to user-defined timestamp (#8946)
Summary: ajkr reminded me that we have a rule of not including per-kv related data in `WriteOptions`. Namely, `WriteOptions` should not include information about "what-to-write", but should just include information about "how-to-write". According to this rule, `WriteOptions::timestamp` (experimental) is clearly a violation. Therefore, this PR removes `WriteOptions::timestamp` for compliance. After the removal, we need to pass timestamp info via another set of APIs. This PR proposes a set of overloaded functions `Put(write_opts, key, value, ts)`, `Delete(write_opts, key, ts)`, and `SingleDelete(write_opts, key, ts)`. Planned to add `Write(write_opts, batch, ts)`, but its complexity made me reconsider doing it in another PR (maybe). For better checking and returning error early, we also add a new set of APIs to `WriteBatch` that take extra `timestamp` information when writing to `WriteBatch`es. These set of APIs in `WriteBatchWithIndex` are currently not supported, and are on our TODO list. Removed `WriteBatch::AssignTimestamps()` and renamed `WriteBatch::AssignTimestamp()` to `WriteBatch::UpdateTimestamps()` since this method require that all keys have space for timestamps allocated already and multiple timestamps can be updated. The constructor of `WriteBatch` now takes a fourth argument `default_cf_ts_sz` which is the timestamp size of the default column family. This will be used to allocate space when calling APIs that do not specify a column family handle. Also, updated `DB::Get()`, `DB::MultiGet()`, `DB::NewIterator()`, `DB::NewIterators()` methods, replacing some assertions about timestamp to returning Status code. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8946 Test Plan: make check ./db_bench -benchmarks=fillseq,fillrandom,readrandom,readseq,deleterandom -user_timestamp_size=8 ./db_stress --user_timestamp_size=8 -nooverwritepercent=0 -test_secondary=0 -secondary_catch_up_one_in=0 -continuous_verification_interval=0 Make sure there is no perf regression by running the following ``` ./db_bench_opt -db=/dev/shm/rocksdb -use_existing_db=0 -level0_stop_writes_trigger=256 -level0_slowdown_writes_trigger=256 -level0_file_num_compaction_trigger=256 -disable_wal=1 -duration=10 -benchmarks=fillrandom ``` Before this PR ``` DB path: [/dev/shm/rocksdb] fillrandom : 1.831 micros/op 546235 ops/sec; 60.4 MB/s ``` After this PR ``` DB path: [/dev/shm/rocksdb] fillrandom : 1.820 micros/op 549404 ops/sec; 60.8 MB/s ``` Reviewed By: ltamasi Differential Revision: D33721359 Pulled By: riversand963 fbshipit-source-id: c131561534272c120ffb80711d42748d21badf09 |
3 years ago |
|
Andrew Kryczka
|
aa2b3bf675 |
Added `TraceOptions::preserve_write_order` (#9334)
Summary: This option causes trace records to be written in the serialized write thread. That way, the write records in the trace must follow the same order as writes that are logged to WAL and writes that are applied to the DB. By default I left it disabled to match existing behavior. I enabled it in `db_stress`, though, as that use case requires order of write records in trace matches the order in WAL. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9334 Test Plan: - See if below unsynced data loss crash test can run for 24h straight. It used to crash after a few hours when reaching an unlucky trace ordering. ``` DEBUG_LEVEL=0 TEST_TMPDIR=/dev/shm /usr/local/bin/python3 -u tools/db_crashtest.py blackbox --interval=10 --max_key=100000 --write_buffer_size=524288 --target_file_size_base=524288 --max_bytes_for_level_base=2097152 --value_size_mult=33 --sync_fault_injection=1 --test_batches_snapshots=0 --duration=86400 ``` Reviewed By: zhichao-cao Differential Revision: D33301990 Pulled By: ajkr fbshipit-source-id: 82d97559727adb4462a7af69758449c8725b22d3 |
3 years ago |
|
mrambacher
|
423538a816 |
Make MemoryAllocator into a Customizable class (#8980)
Summary: - Make MemoryAllocator and its implementations into a Customizable class. - Added a "DefaultMemoryAllocator" which uses new and delete - Added a "CountedMemoryAllocator" that counts the number of allocs and free - Updated the existing tests to use these new allocators - Changed the memkind allocator test into a generic test that can test the various allocators. - Added tests for creating all of the allocators - Added tests to verify/create the JemallocNodumpAllocator using its options. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8980 Reviewed By: zhichao-cao Differential Revision: D32990403 Pulled By: mrambacher fbshipit-source-id: 6fdfe8218c10dd8dfef34344a08201be1fa95c76 |
3 years ago |
|
lgqss
|
77c7085594 |
MemTableList::TrimHistory now use allocated bytes (#9020)
Summary: Fix a bug when both max_write_buffer_size_to_maintain and max_write_buffer_number_to_maintain are 0. The bug was introduced in 6.5.0 and https://github.com/facebook/rocksdb/issues/5022. Fix https://github.com/facebook/rocksdb/issues/8371 Pull Request resolved: https://github.com/facebook/rocksdb/pull/9020 Reviewed By: pdillinger Differential Revision: D32767084 Pulled By: ajkr fbshipit-source-id: c401ee6e2557230e892d0fe8abb4966cbd18e85f |
3 years ago |
|
Jay Zhuang
|
29102641dd |
Skip directory fsync for filesystem btrfs (#8903)
Summary: Directory fsync might be expensive on btrfs and it may not be needed. Here are 4 directory fsync cases: 1. creating a new file: dir-fsync is not needed on btrfs, as long as the new file itself is synced. 2. renaming a file: dir-fsync is not needed if the renamed file is synced. So an API `FsyncAfterFileRename(filename, ...)` is provided to sync the file on btrfs. By default, it just calls dir-fsync. 3. deleting files: dir-fsync is forced by set `IOOptions.force_dir_fsync = true` 4. renaming multiple files (like backup and checkpoint): dir-fsync is forced, the same as above. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8903 Test Plan: run tests on btrfs and non btrfs Reviewed By: ajkr Differential Revision: D30885059 Pulled By: jay-zhuang fbshipit-source-id: dd2730b31580b0bcaedffc318a762d7dbf25de4a |
3 years ago |
|
leipeng
|
2b70224f82 |
remove bad extra RecordTick(stats_, WRITE_WITH_WAL) (#9064)
Summary: This PR fix wrong ticker `WRITE_WITH_WAL`. `RecordTick(WRITE_WITH_WAL)` will be called later in `WriteToWAL` and `ConcurrentWriteToWAL`. Fixes: 1. Delete these two extra `RecordTick(WRITE_WITH_WAL)` 2. Fix corresponding test case Pull Request resolved: https://github.com/facebook/rocksdb/pull/9064 Reviewed By: ajkr Differential Revision: D31944459 Pulled By: riversand963 fbshipit-source-id: f1aa8d2a4320456bc357bc5b0902032f7dcad086 |
3 years ago |
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leipeng
|
0a73ada7b5 |
remove unused local obj and simpilify comple code (#9052)
Summary: This PR does not change code sematics, it just changes for: 1. local obj `nonmem_w` and `lfile` are unused 2. null check for `delete ptr` is unnecessary 3. use `unique_ptr::reset` instead of `release` + `delete` Pull Request resolved: https://github.com/facebook/rocksdb/pull/9052 Reviewed By: zhichao-cao Differential Revision: D31801661 Pulled By: anand1976 fbshipit-source-id: 16a77d45da8c8833bf5bf3bce546bb3711b335df |
3 years ago |
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leipeng
|
0c53b41856 |
db_impl_write.cc: use stats_ instead of immutable_db_options_.stats (#9053)
Summary: This PR has no semantic changes, just to make code shorter. `stats_` has value same with `immutable_db_options_.stats`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9053 Reviewed By: zhichao-cao Differential Revision: D31801603 Pulled By: anand1976 fbshipit-source-id: cbd8fe478d3e90ae078ace49b4f2eb9bb028ccf6 |
3 years ago |
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mrambacher
|
13ae16c315 |
Cleanup includes in dbformat.h (#8930)
Summary: This header file was including everything and the kitchen sink when it did not need to. This resulted in many places including this header when they needed other pieces instead. Cleaned up this header to only include what was needed and fixed up the remaining code to include what was now missing. Hopefully, this sort of code hygiene cleanup will speed up the builds... Pull Request resolved: https://github.com/facebook/rocksdb/pull/8930 Reviewed By: pdillinger Differential Revision: D31142788 Pulled By: mrambacher fbshipit-source-id: 6b45de3f300750c79f751f6227dece9cfd44085d |
3 years ago |
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Akanksha Mahajan
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78afb4d81e |
Support SingleDelete for user-defined timestamps (#8921)
Summary: Added support for SingleDelete for user-defined timestamps. Users can now Get and Iterate over keys deleted with SingleDelete. It also includes changes in CompactionIterator which preserves the same user key with different timestamps, unless the timestamp is below a certain threshold full_history_ts_low. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8921 Test Plan: Added new unit tests Reviewed By: riversand963 Differential Revision: D31098191 Pulled By: akankshamahajan15 fbshipit-source-id: 78a59ef4b4884ae324fcd10f56e62a27d5ee2f49 |
3 years ago |
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eharry
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0b6be7eb68 |
Fix WAL log data corruption #8723 (#8746)
Summary: Fix WAL log data corruption when using DBOptions.manual_wal_flush(true) and WriteOptions.sync(true) together (https://github.com/facebook/rocksdb/issues/8723) Pull Request resolved: https://github.com/facebook/rocksdb/pull/8746 Reviewed By: ajkr Differential Revision: D30758468 Pulled By: riversand963 fbshipit-source-id: 07c20899d5f2447dc77861b4845efc68a59aa4e8 |
3 years ago |
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Yanqin Jin
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2a2b3e03a5 |
Allow WriteBatch to have keys with different timestamp sizes (#8725)
Summary: In the past, we unnecessarily requires all keys in the same write batch to be from column families whose timestamps' formats are the same for simplicity. Specifically, we cannot use the same write batch to write to two column families, one of which enables timestamp while the other disables it. The limitation is due to the member `timestamp_size_` that used to exist in each `WriteBatch` object. We pass a timestamp_size to the constructor of `WriteBatch`. Therefore, users can simply use the old `WriteBatch::Put()`, `WriteBatch::Delete()`, etc APIs for write, while the internal implementation of `WriteBatch` will take care of memory allocation for timestamps. The above is not necessary. One the one hand, users can set up a memory buffer to store user key and then contiguously append the timestamp to the user key. Then the user can pass this buffer to the `WriteBatch::Put(Slice&)` API. On the other hand, users can set up a SliceParts object which is an array of Slices and let the last Slice to point to the memory buffer storing timestamp. Then the user can pass the SliceParts object to the `WriteBatch::Put(SliceParts&)` API. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8725 Test Plan: make check Reviewed By: ltamasi Differential Revision: D30654499 Pulled By: riversand963 fbshipit-source-id: 9d848c77ad3c9dd629aa5fc4e2bc16fb0687b4a2 |
3 years ago |
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Yanqin Jin
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066b51126d |
Several simple local code clean-ups (#8565)
Summary: This PR tries to remove some unnecessary checks as well as unreachable code blocks to improve readability. An obvious non-public API method naming typo is also corrected. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8565 Test Plan: make check Reviewed By: lth Differential Revision: D29963984 Pulled By: riversand963 fbshipit-source-id: cc96e8f09890e5cfe9b20eadb63bdca5484c150a |
3 years ago |
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Baptiste Lemaire
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c521a9ab2b |
Retire superfluous functions introduced in earlier mempurge PRs. (#8558)
Summary: The main challenge to make the memtable garbage collection prototype (nicknamed `mempurge`) was to not get rid of WAL files that contain unflushed (but mempurged) data. That was successfully guaranteed by not writing the VersionEdit to the MANIFEST file after a successful mempurge. By not writing VersionEdits to the `MANIFEST` file after a succesful mempurge operation, we do not change the earliest log file number that contains unflushed data: `cfd->GetLogNumber()` (`cfd->SetLogNumber()` is only called in `VersionSet::ProcessManifestWrites`). As a result, a number of functions introduced earlier just for the mempurge operation are not obscolete/redundant. (e.g.: `FlushJob::ExtractEarliestLogFileNumber`), and this PR aims at cleaning up all these now-unnecessary functions. In particular, we no longer need to store the earliest log file number in the `MemTable` struct itself. This PR therefore also reverts the `MemTable` struct to its original form. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8558 Test Plan: Already included in `db_flush_test.cc`. Reviewed By: anand1976 Differential Revision: D29764351 Pulled By: bjlemaire fbshipit-source-id: 0f43b260fa270251862512f397d3f24ee62e8437 |
3 years ago |
|
sdong
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9e885939a3 |
Change to code for trimmed memtable history is to released outside DB mutex (#8530)
Summary: Currently, the code shows that we delete memtables immedately after it is trimmed from history. Although it should never happen as the super version still holds the memtable, which is only switched after it, it feels a good practice not to do it, but use clean it up in the standard way: put it to WriteContext and clean it after DB mutex. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8530 Test Plan: Run all existing tests. Reviewed By: ajkr Differential Revision: D29703410 fbshipit-source-id: 21d8068ac6377de4b6fa7a89697195742659fde4 |
3 years ago |
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Baptiste Lemaire
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206845c057 |
Mempurge support for wal (#8528)
Summary: In this PR, `mempurge` is made compatible with the Write Ahead Log: in case of recovery, the DB is now capable of recovering the data that was "mempurged" and kept in the `imm()` list of immutable memtables. The twist was to add a uint64_t to the `memtable` struct to store the number of the earliest log file containing entries from the `memtable`. When a `Flush` operation is replaced with a `MemPurge`, the `VersionEdit` (which usually contains the new min log file number to pick up for recovery and the level 0 file path of the newly created SST file) is no longer appended to the manifest log, and every time the `deleteWal` method is called, a check is made on the list of immutable memtables. This PR also includes a unit test that verifies that no data is lost upon Reopening of the database when the mempurge feature is activated. This extensive unit test includes two column families, with valid data contained in the imm() at time of "crash"/reopening (recovery). Pull Request resolved: https://github.com/facebook/rocksdb/pull/8528 Reviewed By: pdillinger Differential Revision: D29701097 Pulled By: bjlemaire fbshipit-source-id: 072a900fb6ccc1edcf5eef6caf88f3060238edf9 |
3 years ago |
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anand76
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d1b70b05a6 |
Avoid passing existing BG error to WriteStatusCheck (#8511)
Summary: In ```DBImpl::WriteImpl()```, we call ```PreprocessWrite()``` which, among other things, checks the BG error and returns it set. This return status is later on passed to ```WriteStatusCheck()```, which calls ```SetBGError()```. This results in a spurious call, and info logs, on every user write request. We should avoid passing the ```PreprocessWrite()``` return status to ```WriteStatusCheck()```, as the former would have called ```SetBGError()``` already if it encountered any new errors, such as error when creating a new WAL file. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8511 Test Plan: Run existing tests Reviewed By: zhichao-cao Differential Revision: D29639917 Pulled By: anand1976 fbshipit-source-id: 19234163969e1645dbeb273712aaf5cd9ea2b182 |
4 years ago |
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Baptiste Lemaire
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837705ad80 |
Make mempurge a background process (equivalent to in-memory compaction). (#8505)
Summary: In https://github.com/facebook/rocksdb/issues/8454, I introduced a new process baptized `MemPurge` (memtable garbage collection). This new PR is built upon this past mempurge prototype. In this PR, I made the `mempurge` process a background task, which provides superior performance since the mempurge process does not cling on the db_mutex anymore, and addresses severe restrictions from the past iteration (including a scenario where the past mempurge was failling, when a memtable was mempurged but was still referred to by an iterator/snapshot/...). Now the mempurge process ressembles an in-memory compaction process: the stack of immutable memtables is filtered out, and the useful payload is used to populate an output memtable. If the output memtable is filled at more than 60% capacity (arbitrary heuristic) the mempurge process is aborted and a regular flush process takes place, else the output memtable is kept in the immutable memtable stack. Note that adding this output memtable to the `imm()` memtable stack does not trigger another flush process, so that the flush thread can go to sleep at the end of a successful mempurge. MemPurge is activated by making the `experimental_allow_mempurge` flag `true`. When activated, the `MemPurge` process will always happen when the flush reason is `kWriteBufferFull`. The 3 unit tests confirm that this process supports `Put`, `Get`, `Delete`, `DeleteRange` operators and is compatible with `Iterators` and `CompactionFilters`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8505 Reviewed By: pdillinger Differential Revision: D29619283 Pulled By: bjlemaire fbshipit-source-id: 8a99bee76b63a8211bff1a00e0ae32360aaece95 |
4 years ago |
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Baptiste Lemaire
|
714ce5041d |
Fix clang_analyzer failure (#8492)
Summary: Previously, the following command: ```USE_CLANG=1 TEST_TMPDIR=/dev/shm/rocksdb OPT=-g make -j$(nproc) analyze``` was raising an error/warning the new_mem could potentially be a `nullptr`. This error appeared due to code changes from https://github.com/facebook/rocksdb/issues/8454, including an if-statement containing "`... && new_mem != nullptr && ...`", which made the analyzer believe that past this `if`-statement, a `new_mem==nullptr` was a possible scenario. This code patch simply introduces `assert`s and removes this condition in the `if`-statement. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8492 Reviewed By: jay-zhuang Differential Revision: D29571275 Pulled By: bjlemaire fbshipit-source-id: 75d72246b70ebbbae7dea11ccb5778686d8bcbea |
4 years ago |
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Baptiste Lemaire
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9dc887ece0 |
Memtable "MemPurge" prototype (#8454)
Summary: Implement an experimental feature called "MemPurge", which consists in purging "garbage" bytes out of a memtable and reuse the memtable struct instead of making it immutable and eventually flushing its content to storage. The prototype is by default deactivated and is not intended for use. It is intended for correctness and validation testing. At the moment, the "MemPurge" feature can be switched on by using the `options.experimental_allow_mempurge` flag. For this early stage, when the allow_mempurge flag is set to `true`, all the flush operations will be rerouted to perform a MemPurge. This is a temporary design decision that will give us the time to explore meaningful heuristics to use MemPurge at the right time for relevant workloads . Moreover, the current MemPurge operation only supports `Puts`, `Deletes`, `DeleteRange` operations, and handles `Iterators` as well as `CompactionFilter`s that are invoked at flush time . Three unit tests are added to `db_flush_test.cc` to test if MemPurge works correctly (and checks that the previously mentioned operations are fully supported thoroughly tested). One noticeable design decision is the timing of the MemPurge operation in the memtable workflow: for this prototype, the mempurge happens when the memtable is switched (and usually made immutable). This is an inefficient process because it implies that the entirety of the MemPurge operation happens while holding the db_mutex. Future commits will make the MemPurge operation a background task (akin to the regular flush operation) and aim at drastically enhancing the performance of this operation. The MemPurge is also not fully "WAL-compatible" yet, but when the WAL is full, or when the regular MemPurge operation fails (or when the purged memtable still needs to be flushed), a regular flush operation takes place. Later commits will also correct these behaviors. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8454 Reviewed By: anand1976 Differential Revision: D29433971 Pulled By: bjlemaire fbshipit-source-id: 6af48213554e35048a7e03816955100a80a26dc5 |
4 years ago |
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mrambacher
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8948dc8524 |
Make ImmutableOptions struct that inherits from ImmutableCFOptions and ImmutableDBOptions (#8262)
Summary: The ImmutableCFOptions contained a bunch of fields that belonged to the ImmutableDBOptions. This change cleans that up by introducing an ImmutableOptions struct. Following the pattern of Options struct, this class inherits from the DB and CFOption structs (of the Immutable form). Only one structural change (the ImmutableCFOptions::fs was changed to a shared_ptr from a raw one) is in this PR. All of the other changes involve moving the member variables from the ImmutableCFOptions into the ImmutableOptions and changing member variables or function parameters as required for compilation purposes. Follow-on PRs may do a further clean-up of the code, such as renaming variables (such as "ImmutableOptions cf_options") and potentially eliminating un-needed function parameters (there is no longer a need to pass both an ImmutableDBOptions and an ImmutableOptions to a function). Pull Request resolved: https://github.com/facebook/rocksdb/pull/8262 Reviewed By: pdillinger Differential Revision: D28226540 Pulled By: mrambacher fbshipit-source-id: 18ae71eadc879dedbe38b1eb8e6f9ff5c7147dbf |
4 years ago |
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Akanksha Mahajan
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596e9008e4 |
Stall writes in WriteBufferManager when memory_usage exceeds buffer_size (#7898)
Summary: When WriteBufferManager is shared across DBs and column families to maintain memory usage under a limit, OOMs have been observed when flush cannot finish but writes continuously insert to memtables. In order to avoid OOMs, when memory usage goes beyond buffer_limit_ and DBs tries to write, this change will stall incoming writers until flush is completed and memory_usage drops. Design: Stall condition: When total memory usage exceeds WriteBufferManager::buffer_size_ (memory_usage() >= buffer_size_) WriterBufferManager::ShouldStall() returns true. DBImpl first block incoming/future writers by calling write_thread_.BeginWriteStall() (which adds dummy stall object to the writer's queue). Then DB is blocked on a state State::Blocked (current write doesn't go through). WBStallInterface object maintained by every DB instance is added to the queue of WriteBufferManager. If multiple DBs tries to write during this stall, they will also be blocked when check WriteBufferManager::ShouldStall() returns true. End Stall condition: When flush is finished and memory usage goes down, stall will end only if memory waiting to be flushed is less than buffer_size/2. This lower limit will give time for flush to complete and avoid continous stalling if memory usage remains close to buffer_size. WriterBufferManager::EndWriteStall() is called, which removes all instances from its queue and signal them to continue. Their state is changed to State::Running and they are unblocked. DBImpl then signal all incoming writers of that DB to continue by calling write_thread_.EndWriteStall() (which removes dummy stall object from the queue). DB instance creates WBMStallInterface which is an interface to block and signal DBs during stall. When DB needs to be blocked or signalled by WriteBufferManager, state_for_wbm_ state is changed accordingly (RUNNING or BLOCKED). Pull Request resolved: https://github.com/facebook/rocksdb/pull/7898 Test Plan: Added a new test db/db_write_buffer_manager_test.cc Reviewed By: anand1976 Differential Revision: D26093227 Pulled By: akankshamahajan15 fbshipit-source-id: 2bbd982a3fb7033f6de6153aa92a221249861aae |
4 years ago |
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Giuseppe Ottaviano
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48cd7a3aae |
Fix flush reason attribution (#8150)
Summary: Current flush reason attribution is misleading or incorrect (depending on what the original intention was): - Flush due to WAL reaching its maximum size is attributed to `kWriteBufferManager` - Flushes due to full write buffer and write buffer manager are not distinguishable, both are attributed to `kWriteBufferFull` This changes the first to a new flush reason `kWALFull`, and splits the second between `kWriteBufferManager` and `kWriteBufferFull`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8150 Reviewed By: zhichao-cao Differential Revision: D27569645 Pulled By: ot fbshipit-source-id: 7e3c8ca186a6e71976e6b8e937297eebd4b769cc |
4 years ago |
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Peter Dillinger
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e7a60d01b2 |
Revamp WriteController (#8064)
Summary: WriteController had a number of issues: * It could introduce a delay of 1ms even if the write rate never exceeded the configured delayed_write_rate. * The DB-wide delayed_write_rate could be exceeded in a number of ways with multiple column families: * Wiping all pending delay "debts" when another column family joins the delay with GetDelayToken(). * Resetting last_refill_time_ to (now + sleep amount) means each column family can write with delayed_write_rate for large writes. * Updating bytes_left_ for a partial refill without updating last_refill_time_ would essentially give out random bonuses, especially to medium-sized writes. Now the code is much simpler, with these issues fixed. See comments in the new code and new (replacement) tests. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8064 Test Plan: new tests, better than old tests Reviewed By: mrambacher Differential Revision: D27064936 Pulled By: pdillinger fbshipit-source-id: 497c23fe6819340b8f3d440bd634d8a2bc47323f |
4 years ago |
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mrambacher
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3dff28cf9b |
Use SystemClock* instead of std::shared_ptr<SystemClock> in lower level routines (#8033)
Summary: For performance purposes, the lower level routines were changed to use a SystemClock* instead of a std::shared_ptr<SystemClock>. The shared ptr has some performance degradation on certain hardware classes. For most of the system, there is no risk of the pointer being deleted/invalid because the shared_ptr will be stored elsewhere. For example, the ImmutableDBOptions stores the Env which has a std::shared_ptr<SystemClock> in it. The SystemClock* within the ImmutableDBOptions is essentially a "short cut" to gain access to this constant resource. There were a few classes (PeriodicWorkScheduler?) where the "short cut" property did not hold. In those cases, the shared pointer was preserved. Using db_bench readrandom perf_level=3 on my EC2 box, this change performed as well or better than 6.17: 6.17: readrandom : 28.046 micros/op 854902 ops/sec; 61.3 MB/s (355999 of 355999 found) 6.18: readrandom : 32.615 micros/op 735306 ops/sec; 52.7 MB/s (290999 of 290999 found) PR: readrandom : 27.500 micros/op 871909 ops/sec; 62.5 MB/s (367999 of 367999 found) (Note that the times for 6.18 are prior to revert of the SystemClock). Pull Request resolved: https://github.com/facebook/rocksdb/pull/8033 Reviewed By: pdillinger Differential Revision: D27014563 Pulled By: mrambacher fbshipit-source-id: ad0459eba03182e454391b5926bf5cdd45657b67 |
4 years ago |