Skip to content
C++ C Other
Find file
Latest commit b040629 @matthewvon matthewvon Merge pull request #185 from basho/mv-expiry-fallback
Mv expiry fallback
Failed to load latest commit information.
db cleanup assert() issues in debug build. two are being simply avoided …
doc merge google's 1.5 release
helpers/memenv clean up redundant code to single RecoveryMmapSize() call. Add sugges…
include/leveldb update write_batch files after adding unit test. Also add unit tests …
leveldb_ee @ 420e456 Corrected management of log::Writer and WritableFile as used with War…
port Move the include statement for cstdatomic to where it is only include…
stubs Created cache warming unit tests. Updated runtime code as necessary f…
table cleanup assert() issues in debug build. two are being simply avoided …
tools address code review comments. add flag to file open to let fadvise st…
util basic fixes to code to survive rollback from expiry enhanced release
.gitignore Lost gitignore entry of dSYM directories.
.gitmodules restructure for Basho EE feature delivery
.travis.yml Turn off travis support for submodules. travis will not have access t…
AUTHORS reverting disastrous MOE commit, returning to r21
LICENSE reverting disastrous MOE commit, returning to r21
Makefile update make process to dynamically define test files instead of stati…
NEWS sync with upstream @ 21409451
README Update README
README.GOOGLE Update README to be Basho specific and set write_buffer size default …
TODO A number of smaller fixes and performance improvements:
build_detect_platform Merge pull request #165 from basho/mv-cache-object-warming

README

leveldb: A key-value store
Authors: Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)

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.
  
Something went wrong with that request. Please try again.