jj1bdx / leveldb Goto Github PK
View Code? Open in Web Editor NEWThis project forked from basho/leveldb
Clone of http://code.google.com/p/leveldb/
License: BSD 3-Clause "New" or "Revised" License
This project forked from basho/leveldb
Clone of http://code.google.com/p/leveldb/
License: BSD 3-Clause "New" or "Revised" License
leveldb: A key-value store Authors: Sanjay Ghemawat ([email protected]) and Jeff Dean ([email protected]) The original Google README is now README.GOOGLE. ** Introduction This repository contains the Google source code as modified to benefit the Riak environment. The typical Riak environment has two attributes that necessitate leveldb adjustments, both in options and code: - production servers: Riak often runs in heavy Internet environments: servers with many CPU cores, lots of memory, and 24x7 disk activity. Basho's leveldb takes advantage of the environment by adding hardware CRC calculation, increasing Bloom filter accuracy, and defaulting to integrity checking enabled. - multiple databases open: Riak opens 8 to 128 databases simultaneously. Google's leveldb supports this, but its background compaction thread can fall behind. leveldb will "stall" new user writes whenever the compaction thread gets too far behind. Basho's leveldb modification include multiple thread blocks that each contain prioritized threads for specific compaction activities. Details for Basho's customizations exist in the leveldb wiki: http://github.com/basho/leveldb/wiki ** Branch pattern This repository follows the Basho standard for branch management as of November 28, 2013. The standard is found here: https://github.com/basho/riak/wiki/Basho-repository-management In summary, the "develop" branch contains the most recently reviewed engineering work. The "master" branch contains the most recently released work, i.e. distributed as part of a Riak release. ** Basic options needed Those wishing to truly savor the benefits of Basho's modifications need to initialize a new leveldb::Options structure similar to the following before each call to leveldb::DB::Open: leveldb::Options * options; options=new Leveldb::Options; options.filter_policy=leveldb::NewBloomFilterPolicy2(16); options.write_buffer_size=62914560; // 60Mbytes options.total_leveldb_mem=2684354560; // 2.5Gbytes (details below) options.env=leveldb::Env::Default(); ** Memory plan Basho's leveldb dramatically departed from Google's original internal memory allotment plan with Riak 2.0. Basho's leveldb uses a methodology called flexcache. The technical details are here: https://github.com/basho/leveldb/wiki/mv-flexcache The key points are: - options.total_leveldb_mem is an allocation for the entire process, not a single database - giving different values to options.total_leveldb_mem on subsequent Open calls causes memory to rearrange to current value across all databases - recommended minimum for Basho's leveldb is 340Mbytes per database. - performance improves rapidly from 340Mbytes to 2.5Gbytes per database (3.0Gbytes if using Riak's active anti-entropy). Even more is nice, but not as helpful. - never assign more than 75% of available RAM to total_leveldb_mem. There is too much unaccounted memory overhead (worse if you use tcmalloc library). - options.max_open_files and options.block_cache should not be used.
A declarative, efficient, and flexible JavaScript library for building user interfaces.
๐ Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
An Open Source Machine Learning Framework for Everyone
The Web framework for perfectionists with deadlines.
A PHP framework for web artisans
Bring data to life with SVG, Canvas and HTML. ๐๐๐
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
Some thing interesting about web. New door for the world.
A server is a program made to process requests and deliver data to clients.
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
Some thing interesting about visualization, use data art
Some thing interesting about game, make everyone happy.
We are working to build community through open source technology. NB: members must have two-factor auth.
Open source projects and samples from Microsoft.
Google โค๏ธ Open Source for everyone.
Alibaba Open Source for everyone
Data-Driven Documents codes.
China tencent open source team.