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
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| docs | ||
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| examples | ||
| file | ||
| fuzz | ||
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| CODE_OF_CONDUCT.md | ||
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| COPYING | ||
| DEFAULT_OPTIONS_HISTORY.md | ||
| defs.bzl | ||
| DUMP_FORMAT.md | ||
| HISTORY.md | ||
| INSTALL.md | ||
| issue_template.md | ||
| LANGUAGE-BINDINGS.md | ||
| LICENSE.Apache | ||
| LICENSE.leveldb | ||
| Makefile | ||
| PLUGINS.md | ||
| README.md | ||
| ROCKSDB_LITE.md | ||
| src.mk | ||
| TARGETS | ||
| thirdparty.inc | ||
| USERS.md | ||
| Vagrantfile | ||
| WINDOWS_PORT.md | ||
RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on LevelDB by Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast key-value server, especially suited for storing data on flash drives. It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF) and Space-Amplification-Factor (SAF). It has multi-threaded compactions, making it especially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/main/examples
See the github wiki for more explanation.
The public interface is in include/. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Design discussions are conducted in https://www.facebook.com/groups/rocksdb.dev/ and https://rocksdb.slack.com/
License
RocksDB is dual-licensed under both the GPLv2 (found in the COPYING file in the root directory) and Apache 2.0 License (found in the LICENSE.Apache file in the root directory). You may select, at your option, one of the above-listed licenses.