ActiveRecord::Bogacs
ActiveRecord (all-year) pooling "alternatives" ... in a relaxed 'spa' fashion.
Bogács is a village in Borsod-Abaúj-Zemplén county, Hungary.
WiP: do not put this on production if you do not understand the consequences!
Install
add this line to your application's Gemfile:
gem 'activerecord-bogacs', :require => 'active_record/bogacs'
... or install it yourself as:
$ gem install activerecord-bogacs
Setup
Bogacs' pools rely on a small monkey-patch that allows to change the AR pool.
The desired pool class needs to be set before establish_connection
happens,
thus an initializer won't work, you might consider setting the pool class at
the bottom of your application.rb e.g. :
Bundler.require(*Rails.groups)
module MyApp
class Application < Rails::Application
# config.middleware.delete 'ActiveRecord::QueryCache'
end
end
# sample AR-Bogacs setup using the "false" pool :
if Rails.env.production?
pool_class = ActiveRecord::Bogacs::FalsePool
ActiveRecord::ConnectionAdapters::ConnectionHandler.connection_pool_class = pool_class
end
pools are expected to work with older ActiveRecord versions, if not let us know.
Default Pool
Meant as a back-port for users stuck with old Rails versions (< 4.0) on production, facing potential (pool related) concurrency bugs e.g. with high-loads under JRuby.
Based on pool code from 4.x (which works much better than any previous version),
with a few minor tunings and extensions such as pool_initial: 0.5
which allows
to specify how many connections to initialize in advance when the pool is created.
False Pool
The false pool won't do any actual pooling, it is assumed that an underlying pool
is configured. Still, it does maintain a hash of AR connections mapped to threads.
Ignores pool related configurations such as pool: 42
or checkout_timeout: 2.5
.
NOTE: be sure to configure an underlying pool e.g. with Trinidad (using the default Tomcat JDBC pool) :
---
http: # true
port: 3000
# ...
extensions:
mysql_dbpool:
url: jdbc:mysql:///my_production
username: root
jndi: jdbc/BogacsDB
initialSize: <%= ENV['POOL_INITIAL'] || 25 %> # connections created on start
maxActive: <%= ENV['POOL_SIZE'] || 100 %> # default 100 (AR pool: size)
maxIdle: <%= ENV['POOL_SIZE'] || 100 %> # max connections kept in the pool
minIdle: <%= ENV['POOL_INITIAL'] || 50 %>
# idle connections are checked periodically (if enabled) and connections
# that been idle for longer than minEvictableIdleTimeMillis will be released
minEvictableIdleTimeMillis: <%= 3 * 60 * 1000 %> # default 60s
# AR checkout_timeout: 5
maxWait: <%= (( ENV['POOL_TIMEOUT'] || 5.0 ).to_f * 1000).to_i %> # default 30s
ActiveRecord-JDBC adapter allows you to lookup connection from JNDI using the following configuration :
production:
adapter: mysql2
jndi: java:/comp/env/jdbc/BogacsDB
NOTE: when using FalsePool
there's nothing to configure (in database.yml)!
Shareable Pool
This pool allows for a database connection to be "shared" among threads, this is very dangerous normally. You will need to understand the underlying driver's connection whether it is thread-safe.
You'll need to manually declare blocks that run with a shared connection (make
sure only read operations happen within such blocks) similar to the built-in
with_connection
e.g. :
cache_fetch( [ 'user', user_id ] ) do
ActiveRecord::Base.with_shared_connection { User.find(user_id) }
end
The pool will only share connections among such blocks and only if it runs out of all connections (until than it will always prefer checking out a connection just like a "regular" pool).
Only tested with ActiveRecord-JDBC-Adapter using the official Postgres' driver.
Copyright
Copyright (c) 2015 Karol Bucek. See LICENSE (http://en.wikipedia.org/wiki/MIT_License) for details.