Summary:
This diff adds support for concurrent adds to the skiplist memtable
implementations. Memory allocation is made thread-safe by the addition of
a spinlock, with small per-core buffers to avoid contention. Concurrent
memtable writes are made via an additional method and don't impose a
performance overhead on the non-concurrent case, so parallelism can be
selected on a per-batch basis.
Write thread synchronization is an increasing bottleneck for higher levels
of concurrency, so this diff adds --enable_write_thread_adaptive_yield
(default off). This feature causes threads joining a write batch
group to spin for a short time (default 100 usec) using sched_yield,
rather than going to sleep on a mutex. If the timing of the yield calls
indicates that another thread has actually run during the yield then
spinning is avoided. This option improves performance for concurrent
situations even without parallel adds, although it has the potential to
increase CPU usage (and the heuristic adaptation is not yet mature).
Parallel writes are not currently compatible with
inplace updates, update callbacks, or delete filtering.
Enable it with --allow_concurrent_memtable_write (and
--enable_write_thread_adaptive_yield). Parallel memtable writes
are performance neutral when there is no actual parallelism, and in
my experiments (SSD server-class Linux and varying contention and key
sizes for fillrandom) they are always a performance win when there is
more than one thread.
Statistics are updated earlier in the write path, dropping the number
of DB mutex acquisitions from 2 to 1 for almost all cases.
This diff was motivated and inspired by Yahoo's cLSM work. It is more
conservative than cLSM: RocksDB's write batch group leader role is
preserved (along with all of the existing flush and write throttling
logic) and concurrent writers are blocked until all memtable insertions
have completed and the sequence number has been advanced, to preserve
linearizability.
My test config is "db_bench -benchmarks=fillrandom -threads=$T
-batch_size=1 -memtablerep=skip_list -value_size=100 --num=1000000/$T
-level0_slowdown_writes_trigger=9999 -level0_stop_writes_trigger=9999
-disable_auto_compactions --max_write_buffer_number=8
-max_background_flushes=8 --disable_wal --write_buffer_size=160000000
--block_size=16384 --allow_concurrent_memtable_write" on a two-socket
Xeon E5-2660 @ 2.2Ghz with lots of memory and an SSD hard drive. With 1
thread I get ~440Kops/sec. Peak performance for 1 socket (numactl
-N1) is slightly more than 1Mops/sec, at 16 threads. Peak performance
across both sockets happens at 30 threads, and is ~900Kops/sec, although
with fewer threads there is less performance loss when the system has
background work.
Test Plan:
1. concurrent stress tests for InlineSkipList and DynamicBloom
2. make clean; make check
3. make clean; DISABLE_JEMALLOC=1 make valgrind_check; valgrind db_bench
4. make clean; COMPILE_WITH_TSAN=1 make all check; db_bench
5. make clean; COMPILE_WITH_ASAN=1 make all check; db_bench
6. make clean; OPT=-DROCKSDB_LITE make check
7. verify no perf regressions when disabled
Reviewers: igor, sdong
Reviewed By: sdong
Subscribers: MarkCallaghan, IslamAbdelRahman, anthony, yhchiang, rven, sdong, guyg8, kradhakrishnan, dhruba
Differential Revision: https://reviews.facebook.net/D50589
This is an Env implementation that mirrors all storage-related methods on
two different backend Env's and verifies that they return the same
results (return status and read results). This is useful for implementing
a new Env and verifying its correctness.
Signed-off-by: Sage Weil <sage@redhat.com>
Summary: This patch moves all posix thread logic to a separate library.
The motivation is to allow another environments to easily reuse posix
threads. HDFS wraps already posix threads; this split would simplify
this code.
Test Plan: No new functionality is added to posix Env or the threading
library, thus the current tests should suffice.
Summary:
This diff is 1/3 in a sequence that introduces a skip list optimized for
a key that is a freshly-allocated const char*. The diff is broken into
pieces to make it easier to review. This piece only introduces the new
type by copying the existing SkipList, with mechanical naming changes
and reformatting.
Test Plan: new unit test
Reviewers: igor, sdong
Reviewed By: sdong
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D51279
Summary: forward_iterator_bench is not stable enough for build. Remove it for now.
Test Plan: Build it with both of CLANG and non-CLANG and make sure it builds.
Reviewers: rven, kradhakrishnan, anthony, yhchiang, igor, IslamAbdelRahman
Reviewed By: igor, IslamAbdelRahman
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D50991
Summary:
Under a tailing workload, there were increased block cache
misses when a memtable was flushed because we were rebuilding iterators
in that case since the version set changed. This was exacerbated in the
case of iterate_upper_bound, since file iterators which were over the
iterate_upper_bound would have been deleted and are now brought back as
part of the Rebuild, only to be deleted again. We now renew the iterators
and only build iterators for files which are added and delete file
iterators for files which are deleted.
Refer to https://reviews.facebook.net/D50463 for previous version
Test Plan: DBTestTailingIterator.TailingIteratorTrimSeekToNext
Reviewers: anthony, IslamAbdelRahman, igor, tnovak, yhchiang, sdong
Reviewed By: sdong
Subscribers: yhchiang, march, dhruba, leveldb, lovro
Differential Revision: https://reviews.facebook.net/D50679
Summary:
This patch adds OptionsUtil::LoadOptionsFromFile() and
OptionsUtil::LoadLatestOptionsFromDB(), which allow developers
to construct DBOptions and ColumnFamilyOptions from a RocksDB
options file. Note that most pointer-typed options such as
merge_operator will not be constructed.
With this API, developers no longer need to remember all the
options in order to reopen an existing rocksdb instance like
the following:
DBOptions db_options;
std::vector<std::string> cf_names;
std::vector<ColumnFamilyOptions> cf_opts;
// Load primitive-typed options from an existing DB
OptionsUtil::LoadLatestOptionsFromDB(
dbname, &db_options, &cf_names, &cf_opts);
// Initialize necessary pointer-typed options
cf_opts[0].merge_operator.reset(new MyMergeOperator());
...
// Construct the vector of ColumnFamilyDescriptor
std::vector<ColumnFamilyDescriptor> cf_descs;
for (size_t i = 0; i < cf_opts.size(); ++i) {
cf_descs.emplace_back(cf_names[i], cf_opts[i]);
}
// Open the DB
DB* db = nullptr;
std::vector<ColumnFamilyHandle*> cf_handles;
auto s = DB::Open(db_options, dbname, cf_descs,
&handles, &db);
Test Plan:
Augment existing tests in column_family_test
options_test
db_test
Reviewers: igor, IslamAbdelRahman, sdong, anthony
Reviewed By: anthony
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D49095
Summary:
This patch allows rocksdb to persist options into a file on
DB::Open, SetOptions, and Create / Drop ColumnFamily.
Options files are created under the same directory as the rocksdb
instance.
In addition, this patch also adds a fail_if_missing_options_file in DBOptions
that makes any function call return non-ok status when it is not able to
persist options properly.
// If true, then DB::Open / CreateColumnFamily / DropColumnFamily
// / SetOptions will fail if options file is not detected or properly
// persisted.
//
// DEFAULT: false
bool fail_if_missing_options_file;
Options file names are formatted as OPTIONS-<number>, and RocksDB
will always keep the latest two options files.
Test Plan:
Add options_file_test.
options_test
column_family_test
Reviewers: igor, IslamAbdelRahman, sdong, anthony
Reviewed By: anthony
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D48285
Summary:
Using a TLS random instance for skiplist makes it smaller
(useful for hash_skiplist_rep) and prepares skiplist for concurrent
adds. This diff also modifies the branching factor math to avoid an
unnecessary division.
This diff has the effect of changing the sequence of skip list node
height choices made by tests, so it has the potential to cause unit
test failures for tests that implicitly rely on the exact structure
of the skip list. Tests that try to exactly trigger a compaction are
likely suspects for this problem (these tests have always been brittle to
changes in the skiplist details). I've minimizes this risk by reseeding
the main thread's Random at the beginning of each test, increasing the
universal compaction size_ratio limit from 101% to 105% for some tests,
and verifying that the tests pass many times.
Test Plan: for i in `seq 0 9`; do make check; done
Reviewers: sdong, igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D50439
Summary:
This patch introduces OptionsSanityCheckLevel internally to enable
sanity check rocksdb options.
Utilities API will be added in the follow-up diffs.
Test Plan: Added more tests in options_test
Reviewers: igor, IslamAbdelRahman, sdong, anthony
Reviewed By: anthony
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D49515
Summary:
This patch introduces utilities/memory, which currently includes
GetApproximateMemoryUsageByType that reports different types of
rocksdb memory usage given a list of input DBs.
The API also take care of the case where Cache could be shared
across multiple column families / multiple db instances.
Currently, it reports memory usage of memtable, table-readers
and cache.
Test Plan: utilities/memory/memory_test.cc
Reviewers: igor, anthony, IslamAbdelRahman, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D49257
Summary: This patch splits the posix storage backend into Env and
the actual *File implementations. The motivation is to allow other Envs
to use posix as a library. This enables a storage backend different from
posix to split its secondary storage between a normal file system
partition managed by posix, and it own media.
Test Plan: No new functionality is added to posix Env or the library,
thus the current tests should suffice.
Summary: In MyRocks, it is sometimes important to get propeties only for the subset of the database. This diff implements the API in RocksDB.
Test Plan: ran the GetPropertiesOfTablesInRange
Reviewers: rven, sdong
Reviewed By: sdong
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D48651
Summary:
We are cleaning up dependencies.
This diff takes a first step at moving memtable files to their own
directory called memtable. In future diffs, we will move other memtable
files from db to memtable.
Test Plan: make check
Reviewers: sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D48915
Summary: As part of cleaning up dependencies for tech debt week, we are moving ldb and sst_dump tools from util to tools, since they are tools.
Test Plan: make check
Reviewers: sdong
Reviewed By: sdong
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D48747
Summary: manual_compaction_test.cc incorrectly in util. Moved to db.
Test Plan: make check
Reviewers: sdong
Reviewed By: sdong
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D48687
Summary:
As part of tech debt week, we are cleaning up dependencies.
This diff moves db_test_util.[h,cc] from util to db directory.
Test Plan: make check
Reviewers: igor, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D48543
Summary:
Refactor dump_tool and undump_tool so that it's possible to use them with customized options
for example setting a specific comparator similar to what Dragon is doing with the LdbTool
https://phabricator.fb.com/diffusion/FBCODE/browse/master/dragon/tools/Ldb.cpp
Test Plan:
compiles
used it to dump / undump a dragon shard
Reviewers: sdong, yhchiang, igor
Reviewed By: igor
Subscribers: dhruba, adsharma
Differential Revision: https://reviews.facebook.net/D47853
This commit adds two new targets to the Makefile: rocksdb.cc and rocksdb.h
These files, when combined with the c.h header, are a self-contained RocksDB
source distribution called an amalgamation. (The name comes from SQLite's, which
is similar in concept.)
The main benefit of an amalgamation is that it's very easy to drop into a
new project. It also compiles faster compared to compiling individual source
files and potentially gives the compiler more opportunity to make optimizations
since it can see all functions at once.
rocksdb.cc and rocksdb.h are generated by a new script, amalgamate.py.
A detailed description of how amalgamate.py works is in a comment at the top of
the file.
There are also some small changes to existing files to enable the amalgamation:
* Use quotes for includes in unity build
* Fix an old header inclusion in util/xfunc.cc
* Move some includes outside ifdef in util/env_hdfs.cc
* Separate out tool sources in Makefile so they won't be included in unity.cc
* Unity build now produces a static library
Closes#733
Summary:
This patch defines the format of RocksDB options file, which
follows the INI file format, and implements functions for its
serialization and deserialization. An example RocksDB options
file can be found in examples/rocksdb_option_file_example.ini.
A typical RocksDB options file has three sections, which are
Version, DBOptions, and more than one CFOptions. The RocksDB
options file in general follows the basic INI file format
with the following extensions / modifications:
* Escaped characters
We escaped the following characters:
- \n -- line feed - new line
- \r -- carriage return
- \\ -- backslash \
- \: -- colon symbol :
- \# -- hash tag #
* Comments
We support # style comments. Comments can appear at the ending
part of a line.
* Statements
A statement is of the form option_name = value.
Each statement contains a '=', where extra white-spaces
are supported. However, we don't support multi-lined statement.
Furthermore, each line can only contain at most one statement.
* Section
Sections are of the form [SecitonTitle "SectionArgument"],
where section argument is optional.
* List
We use colon-separated string to represent a list.
For instance, n1:n2:n3:n4 is a list containing four values.
Below is an example of a RocksDB options file:
[Version]
rocksdb_version=4.0.0
options_file_version=1.0
[DBOptions]
max_open_files=12345
max_background_flushes=301
[CFOptions "default"]
[CFOptions "the second column family"]
[CFOptions "the third column family"]
Test Plan: Added many tests in options_test.cc
Reviewers: igor, IslamAbdelRahman, sdong, anthony
Reviewed By: anthony
Subscribers: maykov, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D46059
Summary:
Fix hex2String performance issues by removing sscanf dependency.
Also fixed some edge case handling (odd length, bad input).
Test Plan: Created a test file which called old and new implementation, and validated results are the same. I'll paste results in the phabricator diff.
Reviewers: igor, rven, anthony, IslamAbdelRahman, kradhakrishnan, yhchiang, sdong
Reviewed By: sdong
Subscribers: thatsafunnyname, leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D46785
Summary:
This is an initial version of bulk load feature
This diff allow us to create sst files, and then bulk load them later, right now the restrictions for loading an sst file are
(1) Memtables are empty
(2) Added sst files have sequence number = 0, and existing values in database have sequence number = 0
(3) Added sst files values are not overlapping
Test Plan: unit testing
Reviewers: igor, ott, sdong
Reviewed By: sdong
Subscribers: leveldb, ott, dhruba
Differential Revision: https://reviews.facebook.net/D39081
Summary:
Builder and CompactionJob share a lot of fairly complex code. This patch
refactors this code into a separate class, the CompactionIterator. Because the
shared code is fairly complex, this patch hopefully improves maintainability.
While there are is a lot of potential for further improvements, the patch is
intentionally pretty close to the original structure because the change is
already complex enough.
Test Plan: make clean all check && ./db_stress
Reviewers: rven, anthony, yhchiang, sdong, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D46197
Summary:
Prototype of API to allow MyRocks to override default Mutex/CondVar used by transactions with their own implementations. They would simply need to pass their own implementations of Mutex/CondVar to the templated TransactionDB::Open().
Default implementation of TransactionDBMutex/TransactionDBCondVar provided (but the code is not currently changed to use this).
Let me know if this API makes sense or if it should be changed
Test Plan: n/a
Reviewers: yhchiang, rven, igor, sdong, spetrunia
Reviewed By: spetrunia
Subscribers: maykov, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D43761
Summary: Provide a way to specify a detailed static error message for a Status without incurring a memcpy. Let me know what people think of this approach.
Test Plan: added simple test
Reviewers: igor, yhchiang, rven, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D44259
Summary:
As I keep adding new features to transactions, I keep creating more duplicate code. This diff cleans this up by creating a base implementation class for Transaction and OptimisticTransaction to inherit from.
The code in TransactionBase.h/.cc is all just copied from elsewhere. The only entertaining part of this class worth looking at is the virtual TryLock method which allows OptimisticTransactions and Transactions to share the same common code for Put/Get/etc.
The rest of this diff is mostly red and easy on the eyes.
Test Plan: No functionality change. existing tests pass.
Reviewers: sdong, jkedgar, rven, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D45135
Summary:
Initial implementation of Pessimistic Transactions. This diff contains the api changes discussed in D38913. This diff is pretty large, so let me know if people would prefer to meet up to discuss it.
MyRocks folks: please take a look at the API in include/rocksdb/utilities/transaction[_db].h and let me know if you have any issues.
Also, you'll notice a couple of TODOs in the implementation of RollbackToSavePoint(). After chatting with Siying, I'm going to send out a separate diff for an alternate implementation of this feature that implements the rollback inside of WriteBatch/WriteBatchWithIndex. We can then decide which route is preferable.
Next, I'm planning on doing some perf testing and then integrating this diff into MongoRocks for further testing.
Test Plan: Unit tests, db_bench parallel testing.
Reviewers: igor, rven, sdong, yhchiang, yoshinorim
Reviewed By: sdong
Subscribers: hermanlee4, maykov, spetrunia, leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D40869
Summary: Implemented this simple wrapper for something else I was working on. Seemed like it makes sense to expose it instead of burying it in some random code.
Test Plan: added test
Reviewers: rven, kradhakrishnan, sdong, yhchiang
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D43293
Summary: The list of info log files of a db can be obtained using the new function.
Test Plan: New test in db_test.cc passed.
Reviewers: yhchiang, IslamAbdelRahman, sdong
Reviewed By: sdong
Subscribers: IslamAbdelRahman, leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D41715
Summary:
Add two unit tests for SyncWAL(). One makes sure SyncWAL() doesn't block writes in the other thread. Another one makes sure SyncWAL() doesn't wait ongoing writes to finish before being executed.
Create a new test file db_wal_test and move two WAL related tests from db_test to here.
Test Plan: Run the new tests
Reviewers: IslamAbdelRahman, rven, kradhakrishnan, kolmike, tnovak, yhchiang
Reviewed By: yhchiang
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D43605
Summary:
Introduce DeleteScheduler that allow enforcing a rate limit on file deletion
Instead of deleting files immediately, files are moved to trash directory and deleted in a background thread that apply sleep penalty between deletes if needed.
I have updated PurgeObsoleteFiles and PurgeObsoleteWALFiles to use the delete_scheduler instead of env_->DeleteFile
Test Plan:
added delete_scheduler_test
existing unit tests
Reviewers: kradhakrishnan, anthony, rven, yhchiang, sdong
Reviewed By: sdong
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D43221
Summary:
Merge pull request #665 by adamretter
Exposes BackupEngine from C++ to the Java API. Previously only BackupableDB was available
Test Plan: BackupEngineTest.java
Reviewers: fyrz, igor, ankgup87, yhchiang
Reviewed By: yhchiang
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D42873
Summary:
This diff adds CompactOnDeletionCollector in utilities/table_properties_collectors,
which applies a sliding window to a sst file and mark this file as need-compaction
when it observe enough deletion entries within the consecutive keys covered by
the sliding window.
Test Plan: compact_on_deletion_collector_test
Reviewers: igor, anthony, IslamAbdelRahman, kradhakrishnan, yoshinorim, sdong
Reviewed By: sdong
Subscribers: maykov, dhruba
Differential Revision: https://reviews.facebook.net/D41175
Summary: Move general compaction tests from db_test.cc to db_compaction_test.cc
Test Plan:
db_test
db_compaction_test
Reviewers: igor, sdong, IslamAbdelRahman, anthony
Reviewed By: anthony
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D42651
Summary: We want to keep Env a think layer for better portability. Less platform dependent codes should be moved out of Env. In this patch, I create a wrapper of file readers and writers, and put rate limiting, write buffering, as well as most perf context instrumentation and random kill out of Env. It will make it easier to maintain multiple Env in the future.
Test Plan: Run all existing unit tests.
Reviewers: anthony, kradhakrishnan, IslamAbdelRahman, yhchiang, igor
Reviewed By: igor
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D42321
Summary: Moved convenience.h out of utilities to remove a dependency on utilities in db.
Test Plan: unit tests. Also compiled a link to the old location to verify the _Pragma works.
Reviewers: sdong, yhchiang, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D42201
Summary: Move UniversalCompaction related db-tests to db_universal_compaction_test.cc
Test Plan:
db_test
db_universal_compaction_test
Reviewers: igor, sdong, IslamAbdelRahman, anthony
Reviewed By: anthony
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D42225
Summary: Make TransactionLogIterator related tests from db_test.cc to db_log_iter_test.cc
Test Plan:
db_test
db_log_iter_test
Reviewers: sdong, IslamAbdelRahman, igor, anthony
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D42045
Summary: Seems like the cleanest way to resolve this is to move CompactedDBImpl into db/. CompactedDBImpl should probably live in the same place as DBImplReadonly since Opening the latter could end up instantiating the former. Both DBImplReadonly and CompactedDBImpl inherit from DBImpl access protected members of DBImpl( and the latter access friendly private methods).
Test Plan: unit tests
Reviewers: sdong, yhchiang, kradhakrishnan, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D42027
Summary:
Move reusable part of db_test.cc to util/db_test_util.h.
This makes it more possible to partition db_test.cc into
multiple smaller test files.
Also, fixed many old lint errors in db_test.
Test Plan: db_test
Reviewers: igor, anthony, IslamAbdelRahman, sdong, kradhakrishnan
Reviewed By: sdong, kradhakrishnan
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D41973
Summary:
When there are multiple column families, the flush in
GetLiveFiles is not atomic, so that there are entries in the wal files
which are needed to get a consisten RocksDB. We now add the log files to
the checkpoint.
Test Plan:
CheckpointCF - This test forces more data to be written to
the other column families after the flush of the first column family but
before the second.
Reviewers: igor, yhchiang, IslamAbdelRahman, anthony, kradhakrishnan, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D40323
Summary:
Allow EventListener::OnCompactionCompleted to return CompactionJobStats,
which contains useful information about a compaction.
Example CompactionJobStats returned by OnCompactionCompleted():
smallest_output_key_prefix 05000000
largest_output_key_prefix 06990000
elapsed_time 42419
num_input_records 300
num_input_files 3
num_input_files_at_output_level 2
num_output_records 200
num_output_files 1
actual_bytes_input 167200
actual_bytes_output 110688
total_input_raw_key_bytes 5400
total_input_raw_value_bytes 300000
num_records_replaced 100
is_manual_compaction 1
Test Plan: Developed a mega test in db_test which covers 20 variables in CompactionJobStats.
Reviewers: rven, igor, anthony, sdong
Reviewed By: sdong
Subscribers: tnovak, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D38463
Summary:
We occasionally get write stalls (>1s Write() calls) on HDD under read load. The following timers explain almost all of the stalls:
- perf_context.db_mutex_lock_nanos
- perf_context.db_condition_wait_nanos
- iostats_context.open_time
- iostats_context.allocate_time
- iostats_context.write_time
- iostats_context.range_sync_time
- iostats_context.logger_time
In my experiments each of these occasionally takes >1s on write path under some workload. There are rare cases when Write() takes long but none of these takes long.
Test Plan: Added code to our application to write the listed timings to log for slow writes. They usually add up to almost exactly the time Write() call took.
Reviewers: rven, yhchiang, sdong
Reviewed By: sdong
Subscribers: march, dhruba, tnovak
Differential Revision: https://reviews.facebook.net/D39177
Nathan Bronson