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
Summary:
Various tests had disabled valgrind due to it slowing down and timing
out (as is the case right now) the CI runs. Where a test was disabled with no comment,
I assumed slowness was the cause. For these tests that were slow under
valgrind, as well as the ones identified in https://github.com/facebook/rocksdb/issues/8352, this PR moves them
behind the compiler flag `-DROCKSDB_FULL_VALGRIND_RUN`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8475
Test Plan: running `make full_valgrind_test`, `make valgrind_test`, `make check`; will verify they appear working correctly
Reviewed By: jay-zhuang
Differential Revision: D29504843
Pulled By: ajkr
fbshipit-source-id: 2aac90749cfbd30d5ce11cb29a07a1b9314eeea7
Summary:
We saw the `Commit()` fail with "Operation expired" so apparently the
expiration time is too short. Increased the magnitude of the times in
this test to make flakiness less likely.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8258
Reviewed By: jay-zhuang
Differential Revision: D28177033
Pulled By: ajkr
fbshipit-source-id: 0357acee6cc14c104b6ccd39231a683a606ab130
Summary:
The WBWI has two differing modes of operation dependent on the value
of the constructor parameter `overwrite_key`.
Currently, regardless of the parameter, neither mode performs as
expected when using Merge. This PR remedies this by correctly invoking
the appropriate Merge Operator before returning results from the WBWI.
Examples of issues that exist which are solved by this PR:
## Example 1 with `overwrite_key=false`
Currently, from an empty database, the following sequence:
```
Put('k1', 'v1')
Merge('k1', 'v2')
Get('k1')
```
Incorrectly yields `v2`, that is to say that the Merge behaves like a Put.
## Example 2 with o`verwrite_key=true`
Currently, from an empty database, the following sequence:
```
Put('k1', 'v1')
Merge('k1', 'v2')
Get('k1')
```
Incorrectly yields `ERROR: kMergeInProgress`.
## Example 3 with `overwrite_key=false`
Currently, with a database containing `('k1' -> 'v1')`, the following sequence:
```
Merge('k1', 'v2')
GetFromBatchAndDB('k1')
```
Incorrectly yields `v1,v2`
## Example 4 with `overwrite_key=true`
Currently, with a database containing `('k1' -> 'v1')`, the following sequence:
```
Merge('k1', 'v1')
GetFromBatchAndDB('k1')
```
Incorrectly yields `ERROR: kMergeInProgress`.
## Example 5 with `overwrite_key=false`
Currently, from an empty database, the following sequence:
```
Put('k1', 'v1')
Merge('k1', 'v2')
GetFromBatchAndDB('k1')
```
Incorrectly yields `v1,v2`
## Example 6 with `overwrite_key=true`
Currently, from an empty database, `('k1' -> 'v1')`, the following sequence:
```
Put('k1', 'v1')
Merge('k1', 'v2')
GetFromBatchAndDB('k1')
```
Incorrectly yields `ERROR: kMergeInProgress`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8135
Reviewed By: pdillinger
Differential Revision: D27657938
Pulled By: mrambacher
fbshipit-source-id: 0fbda6bbc66bedeba96a84786d90141d776297df
Summary:
TransactionDB uses read callback to filter out un-committed data before
a snapshot. But `MultiGet()` API doesn't use that at all, which causes
returning unwanted data.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7963
Test Plan: Added unittest to reproduce
Reviewed By: anand1976
Differential Revision: D26455851
Pulled By: jay-zhuang
fbshipit-source-id: 265276698cf9d8c4cd79e3250ef10d14375bac55
Summary:
Explicitly reject all range deletions on `TransactionDB` or `OptimisticTransactionDB`, except when the user provides sufficient promises that allow us to proceed safely. The necessary promises are described in the API doc for `TransactionDB::DeleteRange()`. There is currently no way to provide enough promises to make it safe in `OptimisticTransactionDB`.
Fixes https://github.com/facebook/rocksdb/issues/7913.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7929
Test Plan: unit tests covering the cases it's permitted/rejected
Reviewed By: ltamasi
Differential Revision: D26240254
Pulled By: ajkr
fbshipit-source-id: 2834a0ce64cc3e4c3799e35b885a5e79c2f4f6d9
Summary:
Memtable bloom filter is useful in many use cases. A default value on with conservative 1.5% memory can benefit more use cases than use cases impacted.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6584
Test Plan: Run all existing tests.
Reviewed By: pdillinger
Differential Revision: D20626739
fbshipit-source-id: 1dd45532b932139552519b8c2682bd954550c2f9
Summary:
When `ASSERT_STATUS_CHECKED` is enabled, `transaction_test` does not pass without this PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7572
Test Plan: `ASSERT_STATUS_CHECKED=1 make -j32 transaction_test && ./transaction_test`
Reviewed By: zhichao-cao
Differential Revision: D24404319
Pulled By: cheng-chang
fbshipit-source-id: 13689035995366ab06d8eada3ea404e45fef8bc5
Summary:
In order to be able to introduce more locking protocols, we need to abstract out the locking subsystem in TransactionDB into a set of interfaces.
PR https://github.com/facebook/rocksdb/pull/7013 introduces interface `LockTracker`. This PR is a follow up to take the first step to abstract out a `LockManager` interface.
Further modifications to the interface may be needed when introducing the first implementation of range lock. But the idea here is to put the range lock implementation based on range tree under the `utilities/transactions/lock/range/range_tree`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7532
Test Plan: point_lock_manager_test
Reviewed By: ajkr
Differential Revision: D24238731
Pulled By: cheng-chang
fbshipit-source-id: 2a9458cd8b3fb008d9529dbc4d3b28c24631f463
Summary:
CLANG analyze is useful before pull request. Add it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7114
Test Plan: Watch the CI results to succeed.
Reviewed By: riversand963
Differential Revision: D22491942
fbshipit-source-id: 9ccad91c6142fedc3d3dd491cf55054827908f36
Summary:
Cleans up some of the dependencies on test code in the Makefile while building tools:
- Moves the test::RandomString, DBBaseTest::RandomString into Random
- Moves the test::RandomHumanReadableString into Random
- Moves the DestroyDir method into file_utils
- Moves the SetupSyncPointsToMockDirectIO into sync_point.
- Moves the FaultInjection Env and FS classes under env
These changes allow all of the tools to build without dependencies on test_util, thereby simplifying the build dependencies. By moving the FaultInjection code, the dependency in db_stress on different libraries for debug vs release was eliminated.
Tested both release and debug builds via Make and CMake for both static and shared libraries.
More work remains to clean up how the tools are built and remove some unnecessary dependencies. There is also more work that should be done to get the Makefile and CMake to align in their builds -- what is in the libraries and the sizes of the executables are different.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7097
Reviewed By: riversand963
Differential Revision: D22463160
Pulled By: pdillinger
fbshipit-source-id: e19462b53324ab3f0b7c72459dbc73165cc382b2
Summary:
This reverts commit 8d87e9cea1.
Based on offline discussions, it's too early to upgrade to gtest 1.10, as it prevents some developers from using an older version of gtest to integrate to some other systems. Revert it for now.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6923
Reviewed By: pdillinger
Differential Revision: D21864799
fbshipit-source-id: d0726b1ff649fc911b9378f1763316200bd363fc
Summary:
x.size() -1 or y - 1 can overflow to an extremely large value when x.size() pr y is 0 when they are unsigned type. The end condition of i in the for loop will be extremely large, potentially causes segment fault. Fix them.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6902
Test Plan: pass make asan_check
Reviewed By: ajkr
Differential Revision: D21843767
Pulled By: zhichao-cao
fbshipit-source-id: 5b8b88155ac5a93d86246d832e89905a783bb5a1
Summary:
In current commit protocol of pessimistic transaction, if the transaction is not prepared before commit, the commit protocol implicitly assumes that the user wants to commit without prepare.
This PR adds TransactionOptions::skip_prepare, the default value is `true` because if set to `false`, all existing users who commit without prepare need to update their code to set skip_prepare to true. Although this does not force the user to explicitly express their intention of skip_prepare, it at least lets the user be aware of the assumption of being able to commit without prepare.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6775
Test Plan: added a new unit test TransactionTest::CommitWithoutPrepare
Reviewed By: lth
Differential Revision: D21313270
Pulled By: cheng-chang
fbshipit-source-id: 3d95b7c9b2d6cdddc09bdd66c561bc4fae8c3251
Summary:
When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433
Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag.
Differential Revision: D19977691
fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e
Summary:
A recent fix related to 2pc https://github.com/facebook/rocksdb/pull/6313/ writes something to WAL, but does not flush or sync. This causes assertion failure "impl->TEST_WALBufferIsEmpty()" if manual_wal_flush = true. We should fsync the entry to make sure a second power reset can recover.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6417
Test Plan: Add manual_wal_flush=true case in TransactionTest.DoubleCrashInRecovery and fix a bug in the test so that the bug can be reproduced. It passes with the fix.
Differential Revision: D19894537
fbshipit-source-id: f1e84e49e2269f583c6019743118292cd8b6598e
Summary:
In WritePrepared there could be gap in sequence numbers. This breaks the trick we use in kPointInTimeRecovery which assume the first seq in the log right after the corrupted log is one larger than the last seq we read from the logs. To let this trick keep working, we add a dummy entry with the expected sequence to the first log right after recovery.
Also in WriteCommitted, if the log right after the corrupted log is empty, since it has no sequence number to let the sequential trick work, it is assumed as unexpected behavior. This is however expected to happen if we close the db after recovering from a corruption and before writing anything new to it. To remedy that, we apply the same technique by writing a dummy entry to the log that is created after the corrupted log.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6313
Differential Revision: D19458291
Pulled By: maysamyabandeh
fbshipit-source-id: 09bc49e574690085df45b034ca863ff315937e2d
Summary:
unordered_write is incompatible with non-zero max_successive_merges. Although we check this at runtime, we currently don't prevent the user from setting this combination in options. This has led to stress tests to fail with this combination is tried in ::SetOptions.
The patch fixes that and also reverts the changes performed by https://github.com/facebook/rocksdb/pull/6254, in which max_successive_merges was mistakenly declared incompatible with unordered_write.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6284
Differential Revision: D19356115
Pulled By: maysamyabandeh
fbshipit-source-id: f06dadec777622bd75f267361c022735cf8cecb6
Summary:
allow_concurrent_memtable_write is incompatible with non-zero max_successive_merges. Although we check this at runtime, we currently don't prevent the user from setting this combination in options. This has led to stress tests to fail with this combination is tried in ::SetOptions. The patch fixes that.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6254
Differential Revision: D19265819
Pulled By: maysamyabandeh
fbshipit-source-id: 47f2e2dc26fe0972c7152f4da15dadb9703f1179
Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6192
Test Plan:
Add a unit test that fails without the fix and passes now
make check
Differential Revision: D19124781
Pulled By: anand1976
fbshipit-source-id: 8c8cb6fa16c3fc23ec011e168561a13f76bbd783
Summary:
Iterators reseek to the target key after iterating over max_sequential_skip_in_iterations invalid values. The logic is susceptible to an infinite loop bug, which has been present with WritePrepared Transactions up until 6.2 release. Although the bug is not present on master, the patch adds a unit test to prevent it from resurfacing again.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5727
Differential Revision: D16952759
Pulled By: maysamyabandeh
fbshipit-source-id: d0d973dddc8dfabd5a794931232aa4c862c74f51
Summary:
MyRocks currently sets `max_write_buffer_number_to_maintain` in order to maintain enough history for transaction conflict checking. The effectiveness of this approach depends on the size of memtables. When memtables are small, it may not keep enough history; when memtables are large, this may consume too much memory.
We are proposing a new way to configure memtable list history: by limiting the memory usage of immutable memtables. The new option is `max_write_buffer_size_to_maintain` and it will take precedence over the old `max_write_buffer_number_to_maintain` if they are both set to non-zero values. The new option accounts for the total memory usage of flushed immutable memtables and mutable memtable. When the total usage exceeds the limit, RocksDB may start dropping immutable memtables (which is also called trimming history), starting from the oldest one.
The semantics of the old option actually works both as an upper bound and lower bound. History trimming will start if number of immutable memtables exceeds the limit, but it will never go below (limit-1) due to history trimming.
In order the mimic the behavior with the new option, history trimming will stop if dropping the next immutable memtable causes the total memory usage go below the size limit. For example, assuming the size limit is set to 64MB, and there are 3 immutable memtables with sizes of 20, 30, 30. Although the total memory usage is 80MB > 64MB, dropping the oldest memtable will reduce the memory usage to 60MB < 64MB, so in this case no memtable will be dropped.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5022
Differential Revision: D14394062
Pulled By: miasantreble
fbshipit-source-id: 60457a509c6af89d0993f988c9b5c2aa9e45f5c5
Summary:
In valgrind_test, TransactionTest.GetWithoutSnapshot ran 2 hours and still didn't finish. Black list from valgrind_test to prevent timeout.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5715
Test Plan: run "make valgrind_test" and see whether the test is still generated.
Differential Revision: D16866009
fbshipit-source-id: 92c78049b0bc1c2b9a0dfc1b7c8a9206b36f02f0
Summary:
The changes transaction_test to set `txn_db_options.default_write_batch_flush_threshold = 1` in order to give better test coverage for WriteUnprepared.
As part of the change, some tests had to be updated.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5658
Differential Revision: D16740468
Pulled By: lth
fbshipit-source-id: 3821eec20baf13917c8c1fab444332f75a509de9
Summary:
Instead of reusing `TransactionOptions::max_write_batch_size` for determining when to flush a write batch for write unprepared, add a new variable called `write_batch_flush_threshold` for this use case instead.
Also add `TransactionDBOptions::default_write_batch_flush_threshold` which sets the default value if `TransactionOptions::write_batch_flush_threshold` is unspecified.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5633
Differential Revision: D16520364
Pulled By: lth
fbshipit-source-id: d75ae5a2141ce7708982d5069dc3f0b58d250e8c
Summary:
Transaction::RollbackToSavePoint undos the modification made since the SavePoint beginning, and also unlocks the corresponding keys, which are tracked in the last SavePoint. Currently ::PopSavePoint simply discard these tracked keys, leaving them locked in the lock manager. This breaks a subsequent ::RollbackToSavePoint behavior as it loses track of such keys, and thus cannot unlock them. The patch fixes ::PopSavePoint by passing on the track key information to the previous SavePoint.
Fixes https://github.com/facebook/rocksdb/issues/5618
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5628
Differential Revision: D16505325
Pulled By: lth
fbshipit-source-id: 2bc3b30963ab4d36d996d1f66543c93abf358980
Summary:
There are a number of fixes in this PR (with most bugs found via the added stress tests):
1. Re-enable reseek optimization. This was initially disabled to avoid infinite loops in https://github.com/facebook/rocksdb/pull/3955 but this can be resolved by remembering not to reseek after a reseek has already been done. This problem only affects forward iteration in `DBIter::FindNextUserEntryInternal`, as we already disable reseeking in `DBIter::FindValueForCurrentKeyUsingSeek`.
2. Verify that ReadOption.snapshot can be safely used for iterator creation. Some snapshots would not give correct results because snaphsot validation would not be enforced, breaking some assumptions in Prev() iteration.
3. In the non-snapshot Get() case, reads done at `LastPublishedSequence` may not be enough, because unprepared sequence numbers are not published. Use `std::max(published_seq, max_visible_seq)` to do lookups instead.
4. Add stress test to test reading own writes.
5. Minor bug in the allow_concurrent_memtable_write case where we forgot to pass in batch_per_txn_.
6. Minor performance optimization in `CalcMaxUnpreparedSequenceNumber` by assigning by reference instead of value.
7. Add some more comments everywhere.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5573
Differential Revision: D16276089
Pulled By: lth
fbshipit-source-id: 18029c944eb427a90a87dee76ac1b23f37ec1ccb
Summary:
This is a port of this PR into WriteUnprepared:
https://github.com/facebook/rocksdb/pull/5014
This also reverts this test change to restore some flaky write unprepared
tests: https://github.com/facebook/rocksdb/pull/5315
Tested with:
$ gtest-parallel ./transaction_test --gtest_filter=MySQLStyleTransactionTest/MySQLStyleTransactionTest.TransactionStressTest/9 --repeat=128
[128/128] MySQLStyleTransactionTest/MySQLStyleTransactionTest.TransactionStressTest/9 (18250 ms)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5439
Differential Revision: D15761405
Pulled By: lth
fbshipit-source-id: ae2581fd942d8a5b3f9278fd6bc3c1ac0b2c964c
Summary:
When using `PRIu64` type of printf specifier, current code base does the following:
```
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
```
However, this can be simplified to
```
#include <cinttypes>
```
as long as flag `-std=c++11` is used.
This should solve issues like https://github.com/facebook/rocksdb/issues/5159
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5402
Differential Revision: D15701195
Pulled By: miasantreble
fbshipit-source-id: 6dac0a05f52aadb55e9728038599d3d2e4b59d03
Summary:
There are too many types of files under util/. Some test related files don't belong to there or just are just loosely related. Mo
ve them to a new directory test_util/, so that util/ is cleaner.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5377
Differential Revision: D15551366
Pulled By: siying
fbshipit-source-id: 0f5c8653832354ef8caa31749c0143815d719e2c
Summary:
WritePrepared transactions when configured with two_write_queues=true offers higher throughput with unordered_write feature without however compromising the rocksdb guarantees. This is because it performs ordering among writes in a 2nd step that is not tied to memtable write speed. The 2nd step is naturally provided by 2PC when the commit phase does the ordering as well. Without 2PC, the 2nd step would only be provided when we use two_write_queues=true, where WritePrepared after performing the writes, in a 2nd step uses the 2nd queue to assign order to the writes.
The patch clarifies the need for two_write_queues=true in the HISTORY and inline comments of unordered_writes. Moreover it extends the stress tests of WritePrepared to unordred_write.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5313
Differential Revision: D15379977
Pulled By: maysamyabandeh
fbshipit-source-id: 5b6f05b9b59285dcbf3b0532215ba9fe7d926e00
Summary:
They are kind of flaky at the moment. Will re-enable it when flakiness is fixed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5315
Differential Revision: D15382744
Pulled By: maysamyabandeh
fbshipit-source-id: 8b2f9d81a4bb34bfd51481727a682d5cd063c5e3
Summary:
The recent improvement in https://github.com/facebook/rocksdb/pull/3661 could cause a deadlock: When writing recoverable state, we also commit its sequence number to commit table, which could result into evicting existing commit entry, which could result into advancing max_evicted_seq_, which would need to get snapshots from database, which requires obtaining db mutex. The patch releases db_mutex before calling the callback in WriteRecoverableState to avoid the potential deadlock. It also improves the stress tests to let the issue be manifested in the tests.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5306
Differential Revision: D15341458
Pulled By: maysamyabandeh
fbshipit-source-id: 05dcbed7e21b789fd1e5fd5ee8eea08077162323
Summary:
Performing unordered writes in rocksdb when unordered_write option is set to true. When enabled the writes to memtable are done without joining any write thread. This offers much higher write throughput since the upcoming writes would not have to wait for the slowest memtable write to finish. The tradeoff is that the writes visible to a snapshot might change over time. If the application cannot tolerate that, it should implement its own mechanisms to work around that. Using TransactionDB with WRITE_PREPARED write policy is one way to achieve that. Doing so increases the max throughput by 2.2x without however compromising the snapshot guarantees.
The patch is prepared based on an original by siying
Existing unit tests are extended to include unordered_write option.
Benchmark Results:
```
TEST_TMPDIR=/dev/shm/ ./db_bench_unordered --benchmarks=fillrandom --threads=32 --num=10000000 -max_write_buffer_number=16 --max_background_jobs=64 --batch_size=8 --writes=3000000 -level0_file_num_compaction_trigger=99999 --level0_slowdown_writes_trigger=99999 --level0_stop_writes_trigger=99999 -enable_pipelined_write=false -disable_auto_compactions --unordered_write=1
```
With WAL
- Vanilla RocksDB: 78.6 MB/s
- WRITER_PREPARED with unordered_write: 177.8 MB/s (2.2x)
- unordered_write: 368.9 MB/s (4.7x with relaxed snapshot guarantees)
Without WAL
- Vanilla RocksDB: 111.3 MB/s
- WRITER_PREPARED with unordered_write: 259.3 MB/s MB/s (2.3x)
- unordered_write: 645.6 MB/s (5.8x with relaxed snapshot guarantees)
- WRITER_PREPARED with unordered_write disable concurrency control: 185.3 MB/s MB/s (2.35x)
Limitations:
- The feature is not yet extended to `max_successive_merges` > 0. The feature is also incompatible with `enable_pipelined_write` = true as well as with `allow_concurrent_memtable_write` = false.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5218
Differential Revision: D15219029
Pulled By: maysamyabandeh
fbshipit-source-id: 38f2abc4af8780148c6128acdba2b3227bc81759
Summary:
MultiGet batching was implemented in #5011 in order to reduce CPU utilization when looking up multiple keys at once. This PR implements corresponding ```MultiGet``` and ```MultiGetSingleCFForUpdate``` in ```rocksdb::Transaction``` that call the underlying batching implementation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5210
Differential Revision: D15048164
Pulled By: anand1976
fbshipit-source-id: c52f6043102ab0cbc723f4cba2a7b7d1767f6f52
Summary:
When ReadOption doesn't specify a snapshot, WritePrepared::Get used kMaxSequenceNumber to avoid the cost of creating a new snapshot object (that requires sync over db_mutex). This creates a race condition if it is reading from the writes of a transaction that had duplicate keys: each instance of duplicate key is inserted with a different sequence number and depending on the ordering the ::Get might skip the newer one and read the older one that is obsolete.
The patch fixes that by using last published seq as the snapshot sequence number. It also adds a check after the read is done to ensure that the max_evicted_seq has not advanced the aforementioned seq, which is a very unlikely event. If it did, then the read is not valid since the seq is not backed by an actually snapshot to let IsInSnapshot handle that properly when an overlapping commit is evicted from commit cache.
A unit test is added to reproduce the race condition with duplicate keys.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5147
Differential Revision: D14758815
Pulled By: maysamyabandeh
fbshipit-source-id: a56915657132cf6ba5e3f5ea1b5d78c803407719
Summary:
Currently the transaction stress tests use thread id as the seed. Since the thread ids are likely to be the same across multiple runs, the seed is thus going to be the same. The patch includes time in calculating the seed to help covering a very different part of state space in each run of the stress tests. To be able to reproduce the bug in case the stress tests failed, it also prints out the time that was used to calculate the seed value.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5004
Differential Revision: D14144356
Pulled By: maysamyabandeh
fbshipit-source-id: 728ed522f550fc8b4f5f9f373259c05fe9a54556
Summary:
The transaction stress tests, stress a high concurrency scenario. In WritePrepared/WriteUnPrepared we need to also stress the scenarios where an inserting/reading transaction is very slow. This would stress the corner cases that the caching is not sufficient and other slower data structures are engaged. To emulate such cases we make use of slow inserter/verifier threads and also reduce the size of cache data structures.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4974
Differential Revision: D14143070
Pulled By: maysamyabandeh
fbshipit-source-id: 81eb674678faf9fae0f654cd60ebcc74e26aeee7
Summary:
Enhance ::Insert and ::Verify test functions to add artificial delay between prepare and commit, and take snapshot and reads respectively. A future PR will make use of these to improve stress tests to test against long-running transactions as well as long-running backup jobs. Also randomly sets set_snapshot to false for inserters to skip setting the snapshot in the initialization phase and let the snapshot be taken later explicitly.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4970
Differential Revision: D14031342
Pulled By: maysamyabandeh
fbshipit-source-id: b52b453751f0b25b81b23c48892bc1d152464cab
