Method: ActiveRecord::ConnectionAdapters::ConnectionPool#initialize

Defined in:
activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

#initialize(pool_config) ⇒ ConnectionPool

Creates a new ConnectionPool object. pool_config is a PoolConfig object which describes database connection information (e.g. adapter, host name, username, password, etc), as well as the maximum size for this ConnectionPool.

The default ConnectionPool maximum size is 5.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb', line 227

def initialize(pool_config)
  super()

  @pool_config = pool_config
  @db_config = pool_config.db_config
  @role = pool_config.role
  @shard = pool_config.shard

  @checkout_timeout = db_config.checkout_timeout
  @idle_timeout = db_config.idle_timeout
  @size = db_config.pool

  # This variable tracks the cache of threads mapped to reserved connections, with the
  # sole purpose of speeding up the +connection+ method. It is not the authoritative
  # registry of which thread owns which connection. Connection ownership is tracked by
  # the +connection.owner+ attr on each +connection+ instance.
  # The invariant works like this: if there is mapping of <tt>thread => conn</tt>,
  # then that +thread+ does indeed own that +conn+. However, an absence of such
  # mapping does not mean that the +thread+ doesn't own the said connection. In
  # that case +conn.owner+ attr should be consulted.
  # Access and modification of <tt>@leases</tt> does not require
  # synchronization.
  @leases = LeaseRegistry.new

  @connections         = []
  @automatic_reconnect = true

  # Connection pool allows for concurrent (outside the main +synchronize+ section)
  # establishment of new connections. This variable tracks the number of threads
  # currently in the process of independently establishing connections to the DB.
  @now_connecting = 0

  @threads_blocking_new_connections = 0

  @available = ConnectionLeasingQueue.new self
  @pinned_connection = nil
  @pinned_connections_depth = 0

  @async_executor = build_async_executor

  @schema_cache = nil

  @reaper = Reaper.new(self, db_config.reaping_frequency)
  @reaper.run
end