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678ba5e41c
Summary:
The first parameter of SyncPoint::Process is "const std::string&". The majority, maybe all, of the actual calls to this function use a "const char *". The conversion before entering the function requires a construction of a std::string object on the heap. This std::object is then typically not needed because first use of the string is a rocksdb::Slice which has a less costly conversion of char * to slice.
Example:
We have a load and iterate test. The test loads 10m keys and iterates most via 10 rocksdb::Iterator objects. We used TCMALLOC to gather information about allocation and space usage during iterators.
- Before this PR: test took 32 min 17 sec
- After this PR: test took 1 min 14 sec
The TCMALLOC top object list before this PR:
<pre>
Total: 5105999 objects
5003717 98.0% 98.0% 5009471 98.1% rocksdb::DBIter::MergeValuesNewToOld (inline)
20260 0.4% 98.4% 20260 0.4% std::__cxx11::basic_string::_M_mutate
15214 0.3% 98.7% 15214 0.3% rocksdb::UncompressBlockContentsForCompressionType (inline)
13408 0.3% 99.0% 13408 0.3% std::_Rb_tree::_M_emplace_hint_unique [clone .constprop.416] (inline)
12957 0.3% 99.2% 12957 0.3% std::_Rb_tree::_M_emplace_hint_unique [clone .constprop.405] (inline)
9327 0.2% 99.4% 9327 0.2% std::_Rb_tree::_M_copy (inline)
7691 0.2% 99.5% 9919 0.2% JVM_FindSignal
2859 0.1% 99.6% 2859 0.1% rocksdb::Cleanable::RegisterCleanup
2844 0.1% 99.7% 2844 0.1% std::map::operator[] (inline)
</pre>
The "MergeValuesNewToOld (inline)" objects are the #define wrappers to SyncPoint::Process. We discovered this in a 5.18 rocksdb release. There TCMALLOC was more specific that std::basic_string was being constructed. I believe that was before SyncPoint::Process was declared inline in subsequent releases.
The TCMALLOC top object list after this PR:
<pre>
Total: 104911 objects
45090 43.0% 43.0% 45090 43.0% rocksdb::Cleanable::RegisterCleanup
29995 28.6% 71.6% 29995 28.6% rocksdb::LRUCacheShard::Insert
15229 14.5% 86.1% 15229 14.5% rocksdb::UncompressBlockContentsForCompressionType (inline)
4373 4.2% 90.3% 4551 4.3% JVM_FindSignal
2881 2.7% 93.0% 2881 2.7% rocksdb::::ReadBlockFromFile (inline)
1162 1.1% 94.1% 1176 1.1% rocksdb::BlockFetcher::ReadBlockContents (inline)
1036 1.0% 95.1% 1036 1.0% std::__cxx11::basic_string::_M_mutate
869 0.8% 95.9% 869 0.8% std::vector::_M_realloc_insert (inline)
806 0.8% 96.7% 806 0.8% SnmpAgent::GetVariables (inline)
</pre>
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9023
Reviewed By: pdillinger
Differential Revision: D31610907
Pulled By: mrambacher
fbshipit-source-id: 574ff51b639dd46ad253a8e664a575f06b7cc85d
102 lines
3.1 KiB
C++
102 lines
3.1 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. 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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#include <assert.h>
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#include <atomic>
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#include <condition_variable>
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#include <functional>
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#include <mutex>
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#include <string>
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#include <thread>
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#include <unordered_map>
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#include <unordered_set>
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#include "memory/concurrent_arena.h"
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#include "port/port.h"
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#include "test_util/sync_point.h"
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#include "util/dynamic_bloom.h"
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#include "util/random.h"
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#pragma once
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#ifndef NDEBUG
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namespace ROCKSDB_NAMESPACE {
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// A hacky allocator for single use.
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// Arena depends on SyncPoint and create circular dependency.
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class SingleAllocator : public Allocator {
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public:
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char* Allocate(size_t) override {
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assert(false);
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return nullptr;
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}
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char* AllocateAligned(size_t bytes, size_t, Logger*) override {
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buf_.resize(bytes);
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return const_cast<char*>(buf_.data());
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}
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size_t BlockSize() const override {
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assert(false);
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return 0;
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}
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private:
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std::string buf_;
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};
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struct SyncPoint::Data {
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Data() : point_filter_(&alloc_, /*total_bits=*/8192), enabled_(false) {}
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// Enable proper deletion by subclasses
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virtual ~Data() {}
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// successor/predecessor map loaded from LoadDependency
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std::unordered_map<std::string, std::vector<std::string>> successors_;
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std::unordered_map<std::string, std::vector<std::string>> predecessors_;
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std::unordered_map<std::string, std::function<void(void*)> > callbacks_;
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std::unordered_map<std::string, std::vector<std::string> > markers_;
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std::unordered_map<std::string, std::thread::id> marked_thread_id_;
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std::mutex mutex_;
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std::condition_variable cv_;
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// sync points that have been passed through
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std::unordered_set<std::string> cleared_points_;
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SingleAllocator alloc_;
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// A filter before holding mutex to speed up process.
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DynamicBloom point_filter_;
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std::atomic<bool> enabled_;
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int num_callbacks_running_ = 0;
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void LoadDependency(const std::vector<SyncPointPair>& dependencies);
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void LoadDependencyAndMarkers(const std::vector<SyncPointPair>& dependencies,
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const std::vector<SyncPointPair>& markers);
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bool PredecessorsAllCleared(const std::string& point);
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void SetCallBack(const std::string& point,
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const std::function<void(void*)>& callback) {
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std::lock_guard<std::mutex> lock(mutex_);
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callbacks_[point] = callback;
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point_filter_.Add(point);
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}
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void ClearCallBack(const std::string& point);
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void ClearAllCallBacks();
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void EnableProcessing() {
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enabled_ = true;
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}
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void DisableProcessing() {
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enabled_ = false;
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}
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void ClearTrace() {
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std::lock_guard<std::mutex> lock(mutex_);
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cleared_points_.clear();
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}
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bool DisabledByMarker(const std::string& point,
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std::thread::id thread_id) {
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auto marked_point_iter = marked_thread_id_.find(point);
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return marked_point_iter != marked_thread_id_.end() &&
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thread_id != marked_point_iter->second;
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}
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void Process(const Slice& point, void* cb_arg);
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};
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} // namespace ROCKSDB_NAMESPACE
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#endif // NDEBUG
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