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158 Commits (3b8164912e1f0333fb3458c99cc3ad2a3c10500e)
| Author | SHA1 | Message | Date |
|---|---|---|---|
Hui Xiao
|
3b8164912e |
Add manual_wal_flush, FlushWAL() to stress/crash test (#10698)
Summary:
**Context/Summary:**
Introduce `manual_wal_flush_one_in` as titled.
- When `manual_wal_flush_one_in > 0`, we also need tracing to correctly verify recovery because WAL data can be lost in this case when `FlushWAL()` is not explicitly called by users of RocksDB (in our case, db stress) and the recovery from such potential WAL data loss is a prefix recovery that requires tracing to verify. As another consequence, we need to disable features can't run under unsync data loss with `manual_wal_flush_one_in`
Incompatibilities fixed along the way:
```
db_stress: db/db_impl/db_impl_open.cc:2063: static rocksdb::Status rocksdb::DBImpl::Open(const rocksdb::DBOptions&, const string&, const std::vector<rocksdb::ColumnFamilyDescriptor>&, std::vector<rocksdb::ColumnFamilyHandle*>*, rocksdb::DB**, bool, bool): Assertion `impl->TEST_WALBufferIsEmpty()' failed.
```
- It turns out that `Writer::AddCompressionTypeRecord` before this assertion `EmitPhysicalRecord(kSetCompressionType, encode.data(), encode.size());` but do not trigger flush if `manual_wal_flush` is set . This leads to `impl->TEST_WALBufferIsEmpty()' is false.
- As suggested, assertion is removed and violation case is handled by `FlushWAL(sync=true)` along with refactoring `TEST_WALBufferIsEmpty()` to be `WALBufferIsEmpty()` since it is used in prod code now.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10698
Test Plan:
- Locally running `python3 tools/db_crashtest.py blackbox --manual_wal_flush_one_in=1 --manual_wal_flush=1 --sync_wal_one_in=100 --atomic_flush=1 --flush_one_in=100 --column_families=3`
- Joined https://github.com/facebook/rocksdb/pull/10624 in auto CI testings with all RocksDB stress/crash test jobs
Reviewed By: ajkr
Differential Revision: D39593752
Pulled By: ajkr
fbshipit-source-id: 3a2135bb792c52d2ffa60257d4fbc557fb04d2ce
|
2 years ago |
|
Peter Dillinger
|
6de7081cf3 |
Always verify SST unique IDs on SST file open (#10532)
Summary: Although we've been tracking SST unique IDs in the DB manifest unconditionally, checking has been opt-in and with an extra pass at DB::Open time. This changes the behavior of `verify_sst_unique_id_in_manifest` to check unique ID against manifest every time an SST file is opened through table cache (normal DB operations), replacing the explicit pass over files at DB::Open time. This change also enables the option by default and removes the "EXPERIMENTAL" designation. One possible criticism is that the option no longer ensures the integrity of a DB at Open time. This is far from an all-or-nothing issue. Verifying the IDs of all SST files hardly ensures all the data in the DB is readable. (VerifyChecksum is supposed to do that.) Also, with max_open_files=-1 (default, extremely common), all SST files are opened at DB::Open time anyway. Implementation details: * `VerifySstUniqueIdInManifest()` functions are the extra/explicit pass that is now removed. * Unit tests that manipulate/corrupt table properties have to opt out of this check, because that corrupts the "actual" unique id. (And even for testing we don't currently have a mechanism to set "no unique id" in the in-memory file metadata for new files.) * A lot of other unit test churn relates to (a) default checking on, and (b) checking on SST open even without DB::Open (e.g. on flush) * Use `FileMetaData` for more `TableCache` operations (in place of `FileDescriptor`) so that we have access to the unique_id whenever we might need to open an SST file. **There is the possibility of performance impact because we can no longer use the more localized `fd` part of an `FdWithKeyRange` but instead follow the `file_metadata` pointer. However, this change (possible regression) is only done for `GetMemoryUsageByTableReaders`.** * Removed a completely unnecessary constructor overload of `TableReaderOptions` Possible follow-up: * Verification only happens when opening through table cache. Are there more places where this should happen? * Improve error message when there is a file size mismatch vs. manifest (FIXME added in the appropriate place). * I'm not sure there's a justification for `FileDescriptor` to be distinct from `FileMetaData`. * I'm skeptical that `FdWithKeyRange` really still makes sense for optimizing some data locality by duplicating some data in memory, but I could be wrong. * An unnecessary overload of NewTableReader was recently added, in the public API nonetheless (though unusable there). It should be cleaned up to put most things under `TableReaderOptions`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10532 Test Plan: updated unit tests Performance test showing no significant difference (just noise I think): `./db_bench -benchmarks=readwhilewriting[-X10] -num=3000000 -disable_wal=1 -bloom_bits=8 -write_buffer_size=1000000 -target_file_size_base=1000000` Before: readwhilewriting [AVG 10 runs] : 68702 (± 6932) ops/sec After: readwhilewriting [AVG 10 runs] : 68239 (± 7198) ops/sec Reviewed By: jay-zhuang Differential Revision: D38765551 Pulled By: pdillinger fbshipit-source-id: a827a708155f12344ab2a5c16e7701c7636da4c2 |
2 years ago |
|
Changyu Bi
|
30bc495c03 |
Skip swaths of range tombstone covered keys in merging iterator (2022 edition) (#10449)
Summary: Delete range logic is moved from `DBIter` to `MergingIterator`, and `MergingIterator` will seek to the end of a range deletion if possible instead of scanning through each key and check with `RangeDelAggregator`. With the invariant that a key in level L (consider memtable as the first level, each immutable and L0 as a separate level) has a larger sequence number than all keys in any level >L, a range tombstone `[start, end)` from level L covers all keys in its range in any level >L. This property motivates optimizations in iterator: - in `Seek(target)`, if level L has a range tombstone `[start, end)` that covers `target.UserKey`, then for all levels > L, we can do Seek() on `end` instead of `target` to skip some range tombstone covered keys. - in `Next()/Prev()`, if the current key is covered by a range tombstone `[start, end)` from level L, we can do `Seek` to `end` for all levels > L. This PR implements the above optimizations in `MergingIterator`. As all range tombstone covered keys are now skipped in `MergingIterator`, the range tombstone logic is removed from `DBIter`. The idea in this PR is similar to https://github.com/facebook/rocksdb/issues/7317, but this PR leaves `InternalIterator` interface mostly unchanged. **Credit**: the cascading seek optimization and the sentinel key (discussed below) are inspired by [Pebble](https://github.com/cockroachdb/pebble/blob/master/merging_iter.go) and suggested by ajkr in https://github.com/facebook/rocksdb/issues/7317. The two optimizations are mostly implemented in `SeekImpl()/SeekForPrevImpl()` and `IsNextDeleted()/IsPrevDeleted()` in `merging_iterator.cc`. See comments for each method for more detail. One notable change is that the minHeap/maxHeap used by `MergingIterator` now contains range tombstone end keys besides point key iterators. This helps to reduce the number of key comparisons. For example, for a range tombstone `[start, end)`, a `start` and an `end` `HeapItem` are inserted into the heap. When a `HeapItem` for range tombstone start key is popped from the minHeap, we know this range tombstone becomes "active" in the sense that, before the range tombstone's end key is popped from the minHeap, all the keys popped from this heap is covered by the range tombstone's internal key range `[start, end)`. Another major change, *delete range sentinel key*, is made to `LevelIterator`. Before this PR, when all point keys in an SST file are iterated through in `MergingIterator`, a level iterator would advance to the next SST file in its level. In the case when an SST file has a range tombstone that covers keys beyond the SST file's last point key, advancing to the next SST file would lose this range tombstone. Consequently, `MergingIterator` could return keys that should have been deleted by some range tombstone. We prevent this by pretending that file boundaries in each SST file are sentinel keys. A `LevelIterator` now only advance the file iterator once the sentinel key is processed. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10449 Test Plan: - Added many unit tests in db_range_del_test - Stress test: `./db_stress --readpercent=5 --prefixpercent=19 --writepercent=20 -delpercent=10 --iterpercent=44 --delrangepercent=2` - Additional iterator stress test is added to verify against iterators against expected state: https://github.com/facebook/rocksdb/issues/10538. This is based on ajkr's previous attempt https://github.com/facebook/rocksdb/pull/5506#issuecomment-506021913. ``` python3 ./tools/db_crashtest.py blackbox --simple --write_buffer_size=524288 --target_file_size_base=524288 --max_bytes_for_level_base=2097152 --compression_type=none --max_background_compactions=8 --value_size_mult=33 --max_key=5000000 --interval=10 --duration=7200 --delrangepercent=3 --delpercent=9 --iterpercent=25 --writepercent=60 --readpercent=3 --prefixpercent=0 --num_iterations=1000 --range_deletion_width=100 --verify_iterator_with_expected_state_one_in=1 ``` - Performance benchmark: I used a similar setup as in the blog [post](http://rocksdb.org/blog/2018/11/21/delete-range.html) that introduced DeleteRange, "a database with 5 million data keys, and 10000 range tombstones (ignoring those dropped during compaction) that were written in regular intervals after 4.5 million data keys were written". As expected, the performance with this PR depends on the range tombstone width. ``` # Setup: TEST_TMPDIR=/dev/shm ./db_bench_main --benchmarks=fillrandom --writes=4500000 --num=5000000 TEST_TMPDIR=/dev/shm ./db_bench_main --benchmarks=overwrite --writes=500000 --num=5000000 --use_existing_db=true --writes_per_range_tombstone=50 # Scan entire DB TEST_TMPDIR=/dev/shm ./db_bench_main --benchmarks=readseq[-X5] --use_existing_db=true --num=5000000 --disable_auto_compactions=true # Short range scan (10 Next()) TEST_TMPDIR=/dev/shm/width-100/ ./db_bench_main --benchmarks=seekrandom[-X5] --use_existing_db=true --num=500000 --reads=100000 --seek_nexts=10 --disable_auto_compactions=true # Long range scan(1000 Next()) TEST_TMPDIR=/dev/shm/width-100/ ./db_bench_main --benchmarks=seekrandom[-X5] --use_existing_db=true --num=500000 --reads=2500 --seek_nexts=1000 --disable_auto_compactions=true ``` Avg over of 10 runs (some slower tests had fews runs): For the first column (tombstone), 0 means no range tombstone, 100-10000 means width of the 10k range tombstones, and 1 means there is a single range tombstone in the entire DB (width is 1000). The 1 tombstone case is to test regression when there's very few range tombstones in the DB, as no range tombstone is likely to take a different code path than with range tombstones. - Scan entire DB | tombstone width | Pre-PR ops/sec | Post-PR ops/sec | ±% | | ------------- | ------------- | ------------- | ------------- | | 0 range tombstone |2525600 (± 43564) |2486917 (± 33698) |-1.53% | | 100 |1853835 (± 24736) |2073884 (± 32176) |+11.87% | | 1000 |422415 (± 7466) |1115801 (± 22781) |+164.15% | | 10000 |22384 (± 227) |227919 (± 6647) |+918.22% | | 1 range tombstone |2176540 (± 39050) |2434954 (± 24563) |+11.87% | - Short range scan | tombstone width | Pre-PR ops/sec | Post-PR ops/sec | ±% | | ------------- | ------------- | ------------- | ------------- | | 0 range tombstone |35398 (± 533) |35338 (± 569) |-0.17% | | 100 |28276 (± 664) |31684 (± 331) |+12.05% | | 1000 |7637 (± 77) |25422 (± 277) |+232.88% | | 10000 |1367 |28667 |+1997.07% | | 1 range tombstone |32618 (± 581) |32748 (± 506) |+0.4% | - Long range scan | tombstone width | Pre-PR ops/sec | Post-PR ops/sec | ±% | | ------------- | ------------- | ------------- | ------------- | | 0 range tombstone |2262 (± 33) |2353 (± 20) |+4.02% | | 100 |1696 (± 26) |1926 (± 18) |+13.56% | | 1000 |410 (± 6) |1255 (± 29) |+206.1% | | 10000 |25 |414 |+1556.0% | | 1 range tombstone |1957 (± 30) |2185 (± 44) |+11.65% | - Microbench does not show significant regression: https://gist.github.com/cbi42/59f280f85a59b678e7e5d8561e693b61 Reviewed By: ajkr Differential Revision: D38450331 Pulled By: cbi42 fbshipit-source-id: b5ef12e8d8c289ed2e163ccdf277f5039b511fca |
2 years ago |
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Peter Dillinger
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c5afbbfe4b |
Don't wait for indirect flush in read-only DB (#10569)
Summary: Some APIs for getting live files, which are used by Checkpoint and BackupEngine, can optionally trigger and wait for a flush. These would deadlock when used on a read-only DB. Here we fix that by assuming the user wants the overall operation to succeed and is OK without flushing (because the DB is read-only). Follow-up work: the same or other issues can be hit by directly invoking some DB functions that are clearly not appropriate for read-only instance, but are not covered by overrides in DBImplReadOnly and CompactedDBImpl. These should be fixed to avoid similar problems on accidental misuse. (Long term, it would be nice to have a DBReadOnly class without those members, like BackupEngineReadOnly.) Pull Request resolved: https://github.com/facebook/rocksdb/pull/10569 Test Plan: tests updated to catch regression (hang before the fix) Reviewed By: riversand963 Differential Revision: D38995759 Pulled By: pdillinger fbshipit-source-id: f5f8bc7123e13cb45bd393dd974d7d6eda20bc68 |
2 years ago |
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Jay Zhuang
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d9e71fb2c5 |
Fix periodic_task unable to re-register the same task type (#10379)
Summary: Timer has a limitation that it cannot re-register a task with the same name, because the cancel only mark the task as invalid and wait for the Timer thread to clean it up later, before the task is cleaned up, the same task name cannot be added. Which makes the task option update likely to fail, which basically cancel and re-register the same task name. Change the periodic task name to a random unique id and store it in periodic_task_scheduler. Also refactor the `periodic_work` to `periodic_task` to make each job function as a `task`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10379 Test Plan: unittests Reviewed By: ajkr Differential Revision: D38000615 Pulled By: jay-zhuang fbshipit-source-id: e4135f9422e3b53aaec8eda54f4e18ce633a279e |
2 years ago |
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Levi Tamasi
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81388b36e0 |
Add support for wide-column point lookups (#10540)
Summary: The patch adds a new API `GetEntity` that can be used to perform wide-column point lookups. It also extends the `Get` code path and the `MemTable` / `MemTableList` and `Version` / `GetContext` logic accordingly so that wide-column entities can be served from both memtables and SSTs. If the result of a lookup is a wide-column entity (`kTypeWideColumnEntity`), it is passed to the application in deserialized form; if it is a plain old key-value (`kTypeValue`), it is presented as a wide-column entity with a single default (anonymous) column. (In contrast, regular `Get` returns plain old key-values as-is, and returns the value of the default column for wide-column entities, see https://github.com/facebook/rocksdb/issues/10483 .) The result of `GetEntity` is a self-contained `PinnableWideColumns` object. `PinnableWideColumns` contains a `PinnableSlice`, which either stores the underlying data in its own buffer or holds on to a cache handle. It also contains a `WideColumns` instance, which indexes the contents of the `PinnableSlice`, so applications can access the values of columns efficiently. There are several pieces of functionality which are currently not supported for wide-column entities: there is currently no `MultiGetEntity` or wide-column iterator; also, `Merge` and `GetMergeOperands` are not supported, and there is no `GetEntity` implementation for read-only and secondary instances. We plan to implement these in future PRs. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10540 Test Plan: `make check` Reviewed By: akankshamahajan15 Differential Revision: D38847474 Pulled By: ltamasi fbshipit-source-id: 42311a34ccdfe88b3775e847a5e2a5296e002b5b |
2 years ago |
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Andrew Kryczka
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504fe4de80 |
Avoid allocations/copies for large `GetMergeOperands()` results (#10458)
Summary: This PR avoids allocations and copies for the result of `GetMergeOperands()` when the average operand size is at least 256 bytes and the total operands size is at least 32KB. The `GetMergeOperands()` already included `PinnableSlice` but was calling `PinSelf()` (i.e., allocating and copying) for each operand. When this optimization takes effect, we instead call `PinSlice()` to skip that allocation and copy. Resources are pinned in order for the `PinnableSlice` to point to valid memory even after `GetMergeOperands()` returns. The pinned resources include a referenced `SuperVersion`, a `MergingContext`, and a `PinnedIteratorsManager`. They are bundled into a `GetMergeOperandsState`. We use `SharedCleanablePtr` to share that bundle among all `PinnableSlice`s populated by `GetMergeOperands()`. That way, the last `PinnableSlice` to be `Reset()` will cleanup the bundle, including unreferencing the `SuperVersion`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10458 Test Plan: - new DB level test - measured benefit/regression in a number of memtable scenarios Setup command: ``` $ ./db_bench -benchmarks=mergerandom -merge_operator=StringAppendOperator -num=$num -writes=16384 -key_size=16 -value_size=$value_sz -compression_type=none -write_buffer_size=1048576000 ``` Benchmark command: ``` ./db_bench -threads=$threads -use_existing_db=true -avoid_flush_during_recovery=true -write_buffer_size=1048576000 -benchmarks=readrandomoperands -merge_operator=StringAppendOperator -num=$num -duration=10 ``` Worst regression is when a key has many tiny operands: - Parameters: num=1 (implying 16384 operands per key), value_sz=8, threads=1 - `GetMergeOperands()` latency increases 682 micros -> 800 micros (+17%) The regression disappears into the noise (<1% difference) if we remove the `Reset()` loop and the size counting loop. The former is arguably needed regardless of this PR as the convention in `Get()` and `MultiGet()` is to `Reset()` the input `PinnableSlice`s at the start. The latter could be optimized to count the size as we accumulate operands rather than after the fact. Best improvement is when a key has large operands and high concurrency: - Parameters: num=4 (implying 4096 operands per key), value_sz=2KB, threads=32 - `GetMergeOperands()` latency decreases 11492 micros -> 437 micros (-96%). Reviewed By: cbi42 Differential Revision: D38336578 Pulled By: ajkr fbshipit-source-id: 48146d127e04cb7f2d4d2939a2b9dff3aba18258 |
2 years ago |
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Peter Dillinger
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27f3af5966 |
Fix serious FSDirectory use-after-Close bug (missing fsync) (#10460)
Summary: TL;DR: due to a recent change, if you drop a column family, often that DB will no longer fsync after writing new SST files to remaining or new column families, which could lead to data loss on power loss. More bug detail: The intent of https://github.com/facebook/rocksdb/issues/10049 was to Close FSDirectory objects at DB::Close time rather than waiting for DB object destruction. Unfortunately, it also closes shared FSDirectory objects on DropColumnFamily (& destroy remaining handles), which can lead to use-after-Close on FSDirectory shared with remaining column families. Those "uses" are only Fsyncs (or redundant Closes). In the default Posix filesystem, an Fsync on a closed FSDirectory is a quiet no-op. Consequently (under most configurations), if you drop a column family, that DB will no longer fsync after writing new SST files to column families sharing the same directory (true under most configurations). More fix detail: Basically, this removes unnecessary Close ops on destroying ColumnFamilyData. We let `shared_ptr` take care of calling the destructor at the right time. If the intent was to require Close be called before destroying FSDirectory, that was not made clear by the author of FileSystem and was not at all enforced by https://github.com/facebook/rocksdb/issues/10049, which could have added `assert(fd_ == -1)` to `~PosixDirectory()` but did not. To keep this fix simple, we relax the unit test for https://github.com/facebook/rocksdb/issues/10049 to allow timely destruction of FSDirectory to suffice as Close (in CountedFileSystem). Added a TODO to revisit that. Also in this PR: * Added a TODO to share FSDirectory instances between DB and its column families. (Already shared among column families.) * Made DB::Close attempt to close all its open FSDirectory objects even if there is a failure in closing one. Also code clean-up around this logic. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10460 Test Plan: add an assert to check for use-after-Close. With that existing tests can detect the misuse. With fix, tests pass (except noted relaxing of unit test for https://github.com/facebook/rocksdb/issues/10049) Reviewed By: ajkr Differential Revision: D38357922 Pulled By: pdillinger fbshipit-source-id: d42079cadbedf0a969f03389bf586b3b4e1f9137 |
2 years ago |
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Wallace
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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 |
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Jay Zhuang
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18a61a1734 |
Fix seqno->time worker not scheduled with multi DB instances (#10383)
Summary: `PeriodicWorkScheduler` is a global singleton, which were used to store per-instance setting `record_seqno_time_cadence_`. Move that to db_impl.h which is per-instance. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10383 Reviewed By: siying Differential Revision: D37928009 Pulled By: jay-zhuang fbshipit-source-id: e517754f4a9db98798ac04f72033d4b517f734e9 |
2 years ago |
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Jay Zhuang
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faa0f9723c |
Tiered compaction: integrate Seqno time mapping with per key placement (#10370)
Summary: Using the Sequence number to time mapping to decide if a key is hot or not in compaction and place it in the corresponding level. Note: the feature is not complete, level compaction will run indefinitely until all penultimate level data is cold and small enough to not trigger compaction. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10370 Test Plan: CI * Run basic db_bench for universal compaction manually Reviewed By: siying Differential Revision: D37892338 Pulled By: jay-zhuang fbshipit-source-id: 792bbd91b1ccc2f62b5d14c53118434bcaac4bbe |
2 years ago |
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Jay Zhuang
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a3acf2ef87 |
Add seqno to time mapping (#10338)
Summary: Which will be used for tiered storage to preclude hot data from compacting to the cold tier (the last level). Internally, adding seqno to time mapping. A periodic_task is scheduled to record the current_seqno -> current_time in certain cadence. When memtable flush, the mapping informaiton is stored in sstable property. During compaction, the mapping information are merged and get the approximate time of sequence number, which is used to determine if a key is recently inserted or not and preclude it from the last level if it's recently inserted (within the `preclude_last_level_data_seconds`). Pull Request resolved: https://github.com/facebook/rocksdb/pull/10338 Test Plan: CI Reviewed By: siying Differential Revision: D37810187 Pulled By: jay-zhuang fbshipit-source-id: 6953be7a18a99de8b1cb3b162d712f79c2b4899f |
2 years ago |
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Yanqin Jin
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7e2004a123 |
Remove unused variables (#10327)
Summary: As title. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10327 Test Plan: make check Reviewed By: gitbw95 Differential Revision: D37699040 Pulled By: riversand963 fbshipit-source-id: 305a88628907a47dea53c4d9aec9c2f5bb9b58df |
2 years ago |
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Levi Tamasi
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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 |
2 years ago |
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Yanqin Jin
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9586dcf1ce |
Expose the initial logger creation error (#10223)
Summary: https://github.com/facebook/rocksdb/issues/9984 changes the behavior of RocksDB: if logger creation failed during `SanitizeOptions()`, `DB::Open()` will fail. However, since `SanitizeOptions()` is called in `DBImpl::DBImpl()`, we cannot directly expose the error to caller without some additional work. This is a first version proposal which: - Adds a new member `init_logger_creation_s` to `DBImpl` to store the result of init logger creation - Checks the error during `DB::Open()` and return it to caller if non-ok This is not very ideal. We can alternatively move the logger creation logic out of the `SanitizeOptions()`. Since `SanitizeOptions()` is used in other places, we need to check whether this change breaks anything in case other callers of `SanitizeOptions()` assumes that a logger should be created. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10223 Test Plan: make check Reviewed By: pdillinger Differential Revision: D37321717 Pulled By: riversand963 fbshipit-source-id: 58042358a86369d606549dd9938933dd47591c4b |
2 years ago |
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Yanqin Jin
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d654888b8f |
Refactor wal filter processing during recovery (#10214)
Summary: So that DBImpl::RecoverLogFiles do not have to deal with implementation details of WalFilter. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10214 Test Plan: make check Reviewed By: ajkr Differential Revision: D37299122 Pulled By: riversand963 fbshipit-source-id: acf1a80f1ef75da393d375f55968b2f3ac189816 |
2 years ago |
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Andrew Kryczka
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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 |
2 years ago |
|
Peter Dillinger
|
3d358a7e25 |
Fix handling of accidental truncation of IDENTITY file (#10173)
Summary: A consequence of https://github.com/facebook/rocksdb/issues/9990 was requiring a non-empty DB ID to generate new SST files. But if the DB ID is not tracked in the manifest and the IDENTITY file is somehow truncated to 0 bytes, then an empty DB ID would be assigned, leading to crash. This change ensures a non-empty DB ID is assigned and set in the IDENTITY file. Also, * Some light refactoring to clean up the logic * (I/O efficiency) If the ID is tracked in the manifest and already matches the IDENTITY file, don't needlessly overwrite the file. * (Debugging) Log the DB ID to info log on open, because sometimes IDENTITY can change if DB is moved around (though it would be unusual for info log to be copied/moved without IDENTITY file) Pull Request resolved: https://github.com/facebook/rocksdb/pull/10173 Test Plan: unit tests expanded/updated Reviewed By: ajkr Differential Revision: D37176545 Pulled By: pdillinger fbshipit-source-id: a9b414cd35bfa33de48af322a36c24538d50bef1 |
2 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 |
2 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 |
2 years ago |
|
zczhu
|
b6de139df5 |
Handle "NotSupported" status by default implementation of Close() in … (#10127)
Summary: The default implementation of Close() function in Directory/FSDirectory classes returns `NotSupported` status. However, we don't want operations that worked in older versions to begin failing after upgrading when run on FileSystems that have not implemented Directory::Close() yet. So we require the upper level that calls Close() function should properly handle "NotSupported" status instead of treating it as an error status. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10127 Reviewed By: ajkr Differential Revision: D36971112 Pulled By: littlepig2013 fbshipit-source-id: 100f0e6ad1191e1acc1ba6458c566a11724cf466 |
2 years ago |
|
zczhu
|
3ee6c9baec |
Consolidate manual_compaction_paused_ check (#10070)
Summary: As pointed out by [https://github.com/facebook/rocksdb/pull/8351#discussion_r645765422](https://github.com/facebook/rocksdb/pull/8351#discussion_r645765422), check `manual_compaction_paused` and `manual_compaction_canceled` can be reduced by setting `*canceled` to be true in `DisableManualCompaction()` and `*canceled` to be false in the last time calling `EnableManualCompaction()`. Changed Tests: The origin `DBTest2.PausingManualCompaction1` uses a callback function to increase `manual_compaction_paused` and the origin CompactionJob/CompactionIterator with `manual_compaction_paused` can detect this. I changed the callback function so that it sets `*canceled` as true if `canceled` is not `nullptr` (to notify CompactionJob/CompactionIterator the compaction has been canceled). Pull Request resolved: https://github.com/facebook/rocksdb/pull/10070 Test Plan: This change does not introduce new features, but some slight difference in compaction implementation. Run the same manual compaction unit tests as before (e.g., PausingManualCompaction[1-4], CancelManualCompaction[1-2], CancelManualCompactionWithListener in db_test2, and db_compaction_test). Reviewed By: ajkr Differential Revision: D36949133 Pulled By: littlepig2013 fbshipit-source-id: c5dc4c956fbf8f624003a0f5ad2690240063a821 |
2 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 |
2 years ago |
|
Zichen Zhu
|
65893ad959 |
Explicitly closing all directory file descriptors (#10049)
Summary: Currently, the DB directory file descriptor is left open until the deconstruction process (`DB::Close()` does not close the file descriptor). To verify this, comment out the lines between `db_ = nullptr` and `db_->Close()` (line 512, 513, 514, 515 in ldb_cmd.cc) to leak the ``db_'' object, build `ldb` tool and run ``` strace --trace=open,openat,close ./ldb --db=$TEST_TMPDIR --ignore_unknown_options put K1 V1 --create_if_missing ``` There is one directory file descriptor that is not closed in the strace log. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10049 Test Plan: Add a new unit test DBBasicTest.DBCloseAllDirectoryFDs: Open a database with different WAL directory and three different data directories, and all directory file descriptors should be closed after calling Close(). Explicitly call Close() after a directory file descriptor is not used so that the counter of directory open and close should be equivalent. Reviewed By: ajkr, hx235 Differential Revision: D36722135 Pulled By: littlepig2013 fbshipit-source-id: 07bdc2abc417c6b30997b9bbef1f79aa757b21ff |
2 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 |
2 years ago |
|
Akanksha Mahajan
|
d04df2752a |
Persist the new MANIFEST after successfully syncing the new WAL during recovery (#9922)
Summary: In case of non-TransactionDB and avoid_flush_during_recovery = true, RocksDB won't flush the data from WAL to L0 for all column families if possible. As a result, not all column families can increase their log_numbers, and min_log_number_to_keep won't change. For transaction DB (.allow_2pc), even with the flush, there may be old WAL files that it must not delete because they can contain data of uncommitted transactions and min_log_number_to_keep won't change. If we persist a new MANIFEST with advanced log_numbers for some column families, then during a second crash after persisting the MANIFEST, RocksDB will see some column families' log_numbers larger than the corrupted wal, and the "column family inconsistency" error will be hit, causing recovery to fail. As a solution, RocksDB will persist the new MANIFEST after successfully syncing the new WAL. If a future recovery starts from the new MANIFEST, then it means the new WAL is successfully synced. Due to the sentinel empty write batch at the beginning, kPointInTimeRecovery of WAL is guaranteed to go after this point. If future recovery starts from the old MANIFEST, it means the writing the new MANIFEST failed. We won't have the "SST ahead of WAL" error. Currently, RocksDB DB::Open() may creates and writes to two new MANIFEST files even before recovery succeeds. This PR buffers the edits in a structure and writes to a new MANIFEST after recovery is successful Pull Request resolved: https://github.com/facebook/rocksdb/pull/9922 Test Plan: 1. Update unit tests to fail without this change 2. make crast_test -j Branch with unit test and no fix https://github.com/facebook/rocksdb/pull/9942 to keep track of unit test (without fix) Reviewed By: riversand963 Differential Revision: D36043701 Pulled By: akankshamahajan15 fbshipit-source-id: 5760970db0a0920fb73d3c054a4155733500acd9 |
2 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 |
2 years ago |
|
Yu Zhang
|
16bdb1f999 |
Add timestamp support to DBImplReadOnly (#10004)
Summary: This PR adds timestamp support to a read only DB instance opened as `DBImplReadOnly`. A follow up PR will add the same support to `CompactedDBImpl`. With this, read only database has these timestamp related APIs: `ReadOptions.timestamp` : read should return the latest data visible to this specified timestamp `Iterator::timestamp()` : returns the timestamp associated with the key, value `DB:Get(..., std::string* timestamp)` : returns the timestamp associated with the key, value in `timestamp` Test plan (on devserver): ``` $COMPILE_WITH_ASAN=1 make -j24 all $./db_with_timestamp_basic_test --gtest_filter=DBBasicTestWithTimestamp.ReadOnlyDB* ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/10004 Reviewed By: riversand963 Differential Revision: D36434422 Pulled By: jowlyzhang fbshipit-source-id: 5d949e65b1ffb845758000e2b310fdd4aae71cfb |
3 years ago |
|
Jay Zhuang
|
c6d326d3d7 |
Track SST unique id in MANIFEST and verify (#9990)
Summary: Start tracking SST unique id in MANIFEST, which is used to verify with SST properties to make sure the SST file is not overwritten or misplaced. A DB option `try_verify_sst_unique_id` is introduced to enable/disable the verification, if enabled, it opens all SST files during DB-open to read the unique_id from table properties (default is false), so it's recommended to use it with `max_open_files = -1` to pre-open the files. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9990 Test Plan: unittests, format-compatible test, mini-crash Reviewed By: anand1976 Differential Revision: D36381863 Pulled By: jay-zhuang fbshipit-source-id: 89ea2eb6b35ed3e80ead9c724eb096083eaba63f |
3 years ago |
|
sdong
|
49628c9a83 |
Use std::numeric_limits<> (#9954)
Summary: Right now we still don't fully use std::numeric_limits but use a macro, mainly for supporting VS 2013. Right now we only support VS 2017 and up so it is not a problem. The code comment claims that MinGW still needs it. We don't have a CI running MinGW so it's hard to validate. since we now require C++17, it's hard to imagine MinGW would still build RocksDB but doesn't support std::numeric_limits<>. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9954 Test Plan: See CI Runs. Reviewed By: riversand963 Differential Revision: D36173954 fbshipit-source-id: a35a73af17cdcae20e258cdef57fcf29a50b49e0 |
3 years ago |
|
Andrew Kryczka
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c5d367f472 |
Revert open logic changes in #9634 (#9906)
Summary: Left HISTORY.md and unit tests. Added a new unit test to repro the corruption scenario that this PR fixes, and HISTORY.md line for that. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9906 Reviewed By: riversand963 Differential Revision: D35940093 Pulled By: ajkr fbshipit-source-id: 9816f99e1ce405ba36f316beb4f6378c37c8c86b |
3 years ago |
|
Akanksha Mahajan
|
ae82d91492 |
Remove corrupted WAL files in kPointRecoveryMode with avoid_flush_duing_recovery set true (#9634)
Summary: 1) In case of non-TransactionDB and avoid_flush_during_recovery = true, RocksDB won't flush the data from WAL to L0 for all column families if possible. As a result, not all column families can increase their log_numbers, and min_log_number_to_keep won't change. 2) For transaction DB (.allow_2pc), even with the flush, there may be old WAL files that it must not delete because they can contain data of uncommitted transactions and min_log_number_to_keep won't change. If we persist a new MANIFEST with advanced log_numbers for some column families, then during a second crash after persisting the MANIFEST, RocksDB will see some column families' log_numbers larger than the corrupted wal, and the "column family inconsistency" error will be hit, causing recovery to fail. As a solution, 1. the corrupted WALs whose numbers are larger than the corrupted wal and smaller than the new WAL will be moved to archive folder. 2. Currently, RocksDB DB::Open() may creates and writes to two new MANIFEST files even before recovery succeeds. This PR buffers the edits in a structure and writes to a new MANIFEST after recovery is successful Pull Request resolved: https://github.com/facebook/rocksdb/pull/9634 Test Plan: 1. Added new unit tests 2. make crast_test -j Reviewed By: riversand963 Differential Revision: D34463666 Pulled By: akankshamahajan15 fbshipit-source-id: e233d3af0ed4e2028ca0cf051e5a334a0fdc9d19 |
3 years ago |
|
Yanqin Jin
|
0ad9ee30ce |
Remove dead code (#9825)
Summary: Options `preserve_deletes` and `iter_start_seqnum` have been removed since 7.0. This PR removes dead code related to these two removed options. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9825 Test Plan: make check Reviewed By: akankshamahajan15 Differential Revision: D35517950 Pulled By: riversand963 fbshipit-source-id: 86282ce5ec4087acb94a06a42a1b6d55b1715482 |
3 years ago |
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Yanqin Jin
|
1a1c5bda23 |
Disallow commit-time-batch for write-prepared/write-unprepared txn conditionally (#9794)
Summary: For write-prepared/write-unprepared transactions, GetCommitTimeWriteBatch() can be used only if the transaction is started with `TransactionOptions::use_only_the_last_commit_time_batch_for_recovery` set to true. Otherwise, it is possible that multiple uncommitted versions of the same key exist in the database. During bottommost compaction, RocksDB may set the sequence numbers of both to zero once they become committed, causing output SST file to have two identical internal keys. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9794 Test Plan: make check pay special attention to the following ``` transaction_test --gtest_filter=MySQLStyleTransactionTest/MySQLStyleTransactionTest.TransactionStressTest/* ``` Reviewed By: lth Differential Revision: D35327214 Pulled By: riversand963 fbshipit-source-id: 3bae00a28359c10e96e4c6f676d20de5610d8a0f |
3 years ago |
|
Jay Zhuang
|
2c8100e60e |
Fix a race condition when disable and enable manual compaction (#9694)
Summary: In https://github.com/facebook/rocksdb/issues/9659, when `DisableManualCompaction()` is issued, the foreground manual compaction thread does not have to wait background compaction thread to finish. Which could be a problem that the user re-enable manual compaction with `EnableManualCompaction()`, it may re-enable the BG compaction which supposed be cancelled. This patch makes the FG compaction wait on `manual_compaction_state.done`, which either be set by BG compaction or Unschedule callback. Then when FG manual compaction thread returns, it should not have BG compaction running. So shared_ptr is no longer needed for `manual_compaction_state`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9694 Test Plan: a StressTest and unittest Reviewed By: ajkr Differential Revision: D34885472 Pulled By: jay-zhuang fbshipit-source-id: e6476175b43e8c59cd49f5c09241036a0716c274 |
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 |
|
Jay Zhuang
|
4dff279b19 |
DisableManualCompaction may fail to cancel an unscheduled task (#9659)
Summary: https://github.com/facebook/rocksdb/issues/9625 didn't change the unschedule condition which was waiting for the background thread to clean-up the compaction. make sure we only unschedule the task when it's scheduled. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9659 Reviewed By: ajkr Differential Revision: D34651820 Pulled By: jay-zhuang fbshipit-source-id: 23f42081b15ec8886cd81cbf131b116e0c74dc2f |
3 years ago |
|
Jay Zhuang
|
09b0e8f2c7 |
Fix a timer crash caused by invalid memory management (#9656)
Summary: Timer crash when multiple DB instances doing heavy DB open and close operations concurrently. Which is caused by adding a timer task with smaller timestamp than the current running task. Fix it by moving the getting new task timestamp part within timer mutex protection. And other fixes: - Disallow adding duplicated function name to timer - Fix a minor memory leak in timer when a running task is cancelled Pull Request resolved: https://github.com/facebook/rocksdb/pull/9656 Reviewed By: ajkr Differential Revision: D34626296 Pulled By: jay-zhuang fbshipit-source-id: 6b6d96a5149746bf503546244912a9e41a0c5f6b |
3 years ago |
|
slk
|
95305c44a1 |
Add OpenAndTrimHistory API to support trimming data with specified timestamp (#9410)
Summary: As disscussed in (https://github.com/facebook/rocksdb/issues/9223), Here added a new API named DB::OpenAndTrimHistory, this API will open DB and trim data to the timestamp specofied by **trim_ts** (The data with newer timestamp than specified trim bound will be removed). This API should only be used at a timestamp-enabled db instance recovery. And this PR implemented a new iterator named HistoryTrimmingIterator to support trimming history with a new API named DB::OpenAndTrimHistory. HistoryTrimmingIterator wrapped around the underlying InternalITerator such that keys whose timestamps newer than **trim_ts** should not be returned to the compaction iterator while **trim_ts** is not null. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9410 Reviewed By: ltamasi Differential Revision: D34410207 Pulled By: riversand963 fbshipit-source-id: e54049dc234eccd673244c566b15df58df5a6236 |
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 |
|
Jay Zhuang
|
db8647969d |
Unschedule manual compaction from thread-pool queue (#9625)
Summary: PR https://github.com/facebook/rocksdb/issues/9557 introduced a race condition between manual compaction foreground thread and background compaction thread. This PR adds the ability to really unschedule manual compaction from thread-pool queue by differentiate tag name for manual compaction and other tasks. Also fix an issue that db `close()` didn't cancel the manual compaction thread. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9625 Test Plan: unittest not hang Reviewed By: ajkr Differential Revision: D34410811 Pulled By: jay-zhuang fbshipit-source-id: cb14065eabb8cf1345fa042b5652d4f788c0c40c |
3 years ago |
|
Andrew Kryczka
|
9983eecdfb |
Dedicate cacheline for DB mutex (#9637)
Summary: We found a case of cacheline bouncing due to writers locking/unlocking `mutex_` and readers accessing `block_cache_tracer_`. We discovered it only after the issue was fixed by https://github.com/facebook/rocksdb/issues/9462 shifting the `DBImpl` members such that `mutex_` and `block_cache_tracer_` were naturally placed in separate cachelines in our regression testing setup. This PR forces the cacheline alignment of `mutex_` so we don't accidentally reintroduce the problem. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9637 Reviewed By: riversand963 Differential Revision: D34502233 Pulled By: ajkr fbshipit-source-id: 46aa313b7fe83e80c3de254e332b6fb242434c07 |
3 years ago |
|
Yanqin Jin
|
1cda273dc3 |
Fix a silent data loss for write-committed txn (#9571)
Summary:
The following sequence of events can cause silent data loss for write-committed
transactions.
```
Time thread 1 bg flush
| db->Put("a")
| txn = NewTxn()
| txn->Put("b", "v")
| txn->Prepare() // writes only to 5.log
| db->SwitchMemtable() // memtable 1 has "a"
| // close 5.log,
| // creates 8.log
| trigger flush
| pick memtable 1
| unlock db mutex
| write new sst
| txn->ctwb->Put("gtid", "1") // writes 8.log
| txn->Commit() // writes to 8.log
| // writes to memtable 2
| compute min_log_number_to_keep_2pc, this
| will be 8 (incorrect).
|
| Purge obsolete wals, including 5.log
|
V
```
At this point, writes of txn exists only in memtable. Close db without flush because db thinks the data in
memtable are backed by log. Then reopen, the writes are lost except key-value pair {"gtid"->"1"},
only the commit marker of txn is in 8.log
The reason lies in `PrecomputeMinLogNumberToKeep2PC()` which calls `FindMinPrepLogReferencedByMemTable()`.
In the above example, when bg flush thread tries to find obsolete wals, it uses the information
computed by `PrecomputeMinLogNumberToKeep2PC()`. The return value of `PrecomputeMinLogNumberToKeep2PC()`
depends on three components
- `PrecomputeMinLogNumberToKeepNon2PC()`. This represents the WAL that has unflushed data. As the name of this method suggests, it does not account for 2PC. Although the keys reside in the prepare section of a previous WAL, the column family references the current WAL when they are actually inserted into the memtable during txn commit.
- `prep_tracker->FindMinLogContainingOutstandingPrep()`. This represents the WAL with a prepare section but the txn hasn't committed.
- `FindMinPrepLogReferencedByMemTable()`. This represents the WAL on which some memtables (mutable and immutable) depend for their unflushed data.
The bug lies in `FindMinPrepLogReferencedByMemTable()`. Originally, this function skips checking the column families
that are being flushed, but the unit test added in this PR shows that they should not be. In this unit test, there is
only the default column family, and one of its memtables has unflushed data backed by a prepare section in 5.log.
We should return this information via `FindMinPrepLogReferencedByMemTable()`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9571
Test Plan:
```
./transaction_test --gtest_filter=*/TransactionTest.SwitchMemtableDuringPrepareAndCommit_WC/*
make check
```
Reviewed By: siying
Differential Revision: D34235236
Pulled By: riversand963
fbshipit-source-id: 120eb21a666728a38dda77b96276c6af72b008b1
|
3 years ago |
|
Jay Zhuang
|
a0c569ee1d |
Cancel manual compaction in thread-pool queue (#9557)
Summary: Fix `DisableManualCompaction()` has to wait scheduled manual compaction to start the execution to cancel the job. When a manual compaction in thread-pool queue is cancel, set the job is_canceled to true and clean the resource. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9557 Test Plan: added unittest that will hang without the change Reviewed By: ajkr Differential Revision: D34214910 Pulled By: jay-zhuang fbshipit-source-id: 89dbaee78ddf26eb13ce862c2b15f4a098b36a78 |
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 |
|
Jay Zhuang
|
980b9ff385 |
Add more micro-benchmark tests (#9436)
Summary: * Add more micro-benchmark tests * Expose an API in DBImpl for waiting for compactions (still not visible to the user) * Add argument name for ribbon_bench * remove benchmark run from CI, as it runs too long. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9436 Test Plan: CI Reviewed By: riversand963 Differential Revision: D33777836 Pulled By: jay-zhuang fbshipit-source-id: c05de3bc082cc05b5d019f00b324e774bf4bbd96 |
3 years ago |
|
Yanqin Jin
|
d10c5c08d3 |
Remove iter_start_seqnum and preserve_deletes (#9430)
Summary: According to https://github.com/facebook/rocksdb/blob/6.27.fb/db/db_impl/db_impl.cc#L2896:L2911 and https://github.com/facebook/rocksdb/blob/6.27.fb/db/db_impl/db_impl_open.cc#L203:L208, we are going to remove `iter_start_seqnum` and `preserve_deletes` starting from RocksDB 7.0 Pull Request resolved: https://github.com/facebook/rocksdb/pull/9430 Test Plan: make check and CI Reviewed By: ajkr Differential Revision: D33753639 Pulled By: riversand963 fbshipit-source-id: c80aab8e8d8fc33e52472fed524ed703d0ffc8b6 |
3 years ago |
|
slk
|
2e5f764294 |
Make IncreaseFullHistoryTsLow to a public API (#9221)
Summary: As (https://github.com/facebook/rocksdb/issues/9210) discussed, the **full_history_ts_low** is a member of CompactRangeOptions currently, which means a CF's fullHistoryTsLow is advanced only when users submit a CompactRange request. However, users may want to advance the fllHistoryTsLow without an immediate compact. This merge make IncreaseFullHistoryTsLow to a public API so users can advance each CF's fullHistoryTsLow seperately. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9221 Reviewed By: akankshamahajan15 Differential Revision: D33201106 Pulled By: riversand963 fbshipit-source-id: 9cb1d013ba93260f72e16353e693ffee167b47ee |
3 years ago |
|
Andrew Kryczka
|
538d2365e9 |
Fix race condition in BackupEngineTest.ChangeManifestDuringBackupCreation (#9327)
Summary:
The failure looked like this:
```
utilities/backupable/backupable_db_test.cc:3161: Failure
Value of: db_chroot_env_->FileExists(prev_manifest_path).IsNotFound()
Actual: false
Expected: true
```
The failure could be coerced consistently with the following patch:
```
diff --git a/db/db_impl/db_impl_compaction_flush.cc b/db/db_impl/db_impl_compaction_flush.cc
index 80410f671..637636791 100644
--- a/db/db_impl/db_impl_compaction_flush.cc
+++ b/db/db_impl/db_impl_compaction_flush.cc
@@ -2772,6 +2772,8 @@ void DBImpl::BackgroundCallFlush(Env::Priority thread_pri) {
if (job_context.HaveSomethingToClean() ||
job_context.HaveSomethingToDelete() || !log_buffer.IsEmpty()) {
mutex_.Unlock();
+ bg_cv_.SignalAll();
+ sleep(1);
TEST_SYNC_POINT("DBImpl::BackgroundCallFlush:FilesFound");
// Have to flush the info logs before bg_flush_scheduled_--
// because if bg_flush_scheduled_ becomes 0 and the lock is
```
The cause was a familiar problem, which is manual flush/compaction may
return before files they obsoleted are removed. The solution is just to
wait for "scheduled" work to complete, which includes all phases
including cleanup.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9327
Test Plan:
after this PR, even the above patch to coerce the bug cannot
cause the test to fail.
Reviewed By: riversand963
Differential Revision: D33252208
Pulled By: ajkr
fbshipit-source-id: 720a7eaca58c7247d221911fffe3d5e1dbf581e9
|
3 years ago |
|
Peter Dillinger
|
0050a73a4f |
New stable, fixed-length cache keys (#9126)
Summary: This change standardizes on a new 16-byte cache key format for block cache (incl compressed and secondary) and persistent cache (but not table cache and row cache). The goal is a really fast cache key with practically ideal stability and uniqueness properties without external dependencies (e.g. from FileSystem). A fixed key size of 16 bytes should enable future optimizations to the concurrent hash table for block cache, which is a heavy CPU user / bottleneck, but there appears to be measurable performance improvement even with no changes to LRUCache. This change replaces a lot of disjointed and ugly code handling cache keys with calls to a simple, clean new internal API (cache_key.h). (Preserving the old cache key logic under an option would be very ugly and likely negate the performance gain of the new approach. Complete replacement carries some inherent risk, but I think that's acceptable with sufficient analysis and testing.) The scheme for encoding new cache keys is complicated but explained in cache_key.cc. Also: EndianSwapValue is moved to math.h to be next to other bit operations. (Explains some new include "math.h".) ReverseBits operation added and unit tests added to hash_test for both. Fixes https://github.com/facebook/rocksdb/issues/7405 (presuming a root cause) Pull Request resolved: https://github.com/facebook/rocksdb/pull/9126 Test Plan: ### Basic correctness Several tests needed updates to work with the new functionality, mostly because we are no longer relying on filesystem for stable cache keys so table builders & readers need more context info to agree on cache keys. This functionality is so core, a huge number of existing tests exercise the cache key functionality. ### Performance Create db with `TEST_TMPDIR=/dev/shm ./db_bench -bloom_bits=10 -benchmarks=fillrandom -num=3000000 -partition_index_and_filters` And test performance with `TEST_TMPDIR=/dev/shm ./db_bench -readonly -use_existing_db -bloom_bits=10 -benchmarks=readrandom -num=3000000 -duration=30 -cache_index_and_filter_blocks -cache_size=250000 -threads=4` using DEBUG_LEVEL=0 and simultaneous before & after runs. Before ops/sec, avg over 100 runs: 121924 After ops/sec, avg over 100 runs: 125385 (+2.8%) ### Collision probability I have built a tool, ./cache_bench -stress_cache_key to broadly simulate host-wide cache activity over many months, by making some pessimistic simplifying assumptions: * Every generated file has a cache entry for every byte offset in the file (contiguous range of cache keys) * All of every file is cached for its entire lifetime We use a simple table with skewed address assignment and replacement on address collision to simulate files coming & going, with quite a variance (super-Poisson) in ages. Some output with `./cache_bench -stress_cache_key -sck_keep_bits=40`: ``` Total cache or DBs size: 32TiB Writing 925.926 MiB/s or 76.2939TiB/day Multiply by 9.22337e+18 to correct for simulation losses (but still assume whole file cached) ``` These come from default settings of 2.5M files per day of 32 MB each, and `-sck_keep_bits=40` means that to represent a single file, we are only keeping 40 bits of the 128-bit cache key. With file size of 2\*\*25 contiguous keys (pessimistic), our simulation is about 2\*\*(128-40-25) or about 9 billion billion times more prone to collision than reality. More default assumptions, relatively pessimistic: * 100 DBs in same process (doesn't matter much) * Re-open DB in same process (new session ID related to old session ID) on average every 100 files generated * Restart process (all new session IDs unrelated to old) 24 times per day After enough data, we get a result at the end: ``` (keep 40 bits) 17 collisions after 2 x 90 days, est 10.5882 days between (9.76592e+19 corrected) ``` If we believe the (pessimistic) simulation and the mathematical generalization, we would need to run a billion machines all for 97 billion days to expect a cache key collision. To help verify that our generalization ("corrected") is robust, we can make our simulation more precise with `-sck_keep_bits=41` and `42`, which takes more running time to get enough data: ``` (keep 41 bits) 16 collisions after 4 x 90 days, est 22.5 days between (1.03763e+20 corrected) (keep 42 bits) 19 collisions after 10 x 90 days, est 47.3684 days between (1.09224e+20 corrected) ``` The generalized prediction still holds. With the `-sck_randomize` option, we can see that we are beating "random" cache keys (except offsets still non-randomized) by a modest amount (roughly 20x less collision prone than random), which should make us reasonably comfortable even in "degenerate" cases: ``` 197 collisions after 1 x 90 days, est 0.456853 days between (4.21372e+18 corrected) ``` I've run other tests to validate other conditions behave as expected, never behaving "worse than random" unless we start chopping off structured data. Reviewed By: zhichao-cao Differential Revision: D33171746 Pulled By: pdillinger fbshipit-source-id: f16a57e369ed37be5e7e33525ace848d0537c88f |
3 years ago |