Use optimized folly DistributedMutex in LRUCache when available (#10179)
Summary: folly DistributedMutex is faster than standard mutexes though imposes some static obligations on usage. See https://github.com/facebook/folly/blob/main/folly/synchronization/DistributedMutex.h for details. Here we use this alternative for our Cache implementations (especially LRUCache) for better locking performance, when RocksDB is compiled with folly. Also added information about which distributed mutex implementation is being used to cache_bench output and to DB LOG. Intended follow-up: * Use DMutex in more places, perhaps improving API to support non-scoped locking * Fix linking with fbcode compiler (needs ROCKSDB_NO_FBCODE=1 currently) Credit: Thanks Siying for reminding me about this line of work that was previously left unfinished. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10179 Test Plan: for correctness, existing tests. CircleCI config updated. Also Meta-internal buck build updated. For performance, ran simultaneous before & after cache_bench. Out of three comparison runs, the middle improvement to ops/sec was +21%: Baseline: USE_CLANG=1 DEBUG_LEVEL=0 make -j24 cache_bench (fbcode compiler) ``` Complete in 20.201 s; Rough parallel ops/sec = 1584062 Thread ops/sec = 107176 Operation latency (ns): Count: 32000000 Average: 9257.9421 StdDev: 122412.04 Min: 134 Median: 3623.0493 Max: 56918500 Percentiles: P50: 3623.05 P75: 10288.02 P99: 30219.35 P99.9: 683522.04 P99.99: 7302791.63 ``` New: (add USE_FOLLY=1) ``` Complete in 16.674 s; Rough parallel ops/sec = 1919135 (+21%) Thread ops/sec = 135487 Operation latency (ns): Count: 32000000 Average: 7304.9294 StdDev: 108530.28 Min: 132 Median: 3777.6012 Max: 91030902 Percentiles: P50: 3777.60 P75: 10169.89 P99: 24504.51 P99.9: 59721.59 P99.99: 1861151.83 ``` Reviewed By: anand1976 Differential Revision: D37182983 Pulled By: pdillinger fbshipit-source-id: a17eb05f25b832b6a2c1356f5c657e831a5af8d1main
Peter Dillinger
3 years ago
committed by
Facebook GitHub Bot
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// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once |
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#include "rocksdb/rocksdb_namespace.h" |
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// This file declares a wrapper around the efficient folly DistributedMutex
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// that falls back on a standard mutex when not available. See
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// https://github.com/facebook/folly/blob/main/folly/synchronization/DistributedMutex.h
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// for benefits and limitations.
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// At the moment, only scoped locking is supported using DMutexLock
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// RAII wrapper, because lock/unlock APIs will vary.
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#ifdef USE_FOLLY |
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#include <folly/synchronization/DistributedMutex.h> |
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namespace ROCKSDB_NAMESPACE { |
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class DMutex : public folly::DistributedMutex { |
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public: |
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static const char* kName() { return "folly::DistributedMutex"; } |
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explicit DMutex(bool IGNORED_adaptive = false) { (void)IGNORED_adaptive; } |
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// currently no-op
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void AssertHeld() {} |
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}; |
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using DMutexLock = std::lock_guard<folly::DistributedMutex>; |
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} // namespace ROCKSDB_NAMESPACE
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#else |
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#include "port/port.h" |
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namespace ROCKSDB_NAMESPACE { |
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using DMutex = port::Mutex; |
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using DMutexLock = std::lock_guard<DMutex>; |
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} // namespace ROCKSDB_NAMESPACE
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#endif |
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