class ActiveRecord::ConnectionAdapters::ConnectionPool

def initialize(pool_config)

Experimental RBS support (using type sampling data from the type_fusion project). 

def initialize: (*unused *) -> void

This signature was generated using 1 sample from 1 application.

The default ConnectionPool maximum size is 5.

this ConnectionPool.
host name, username, password, etc), as well as the maximum size for
object which describes database connection information (e.g. adapter,
Creates a new ConnectionPool object. +pool_config+ is a PoolConfig 
def initialize(pool_config)
  super()
  @pool_config = pool_config
  @db_config = pool_config.db_config
  @connection_class = pool_config.connection_class
  @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>@thread_cached_conns</tt> does not require
  # synchronization.
  @thread_cached_conns = Concurrent::Map.new(initial_capacity: @size)
  @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
  @lock_thread = false
  @async_executor = build_async_executor
  lazily_set_schema_cache
  @reaper = Reaper.new(self, db_config.reaping_frequency)
  @reaper.run
end