From 5e024070ab3766fada222053d1e0f1116aeb50a6 Mon Sep 17 00:00:00 2001 From: Matt Jones Date: Tue, 23 Dec 2014 09:54:52 -0500 Subject: Fix connection leak when a thread checks in additional connections. The code in `ConnectionPool#release` assumed that a single thread only ever holds a single connection, and thus that releasing a connection only requires the owning thread_id. There is a trivial counterexample to this assumption: code that checks out additional connections from the pool in the same thread. For instance: connection_1 = ActiveRecord::Base.connection connection_2 = ActiveRecord::Base.connection_pool.checkout ActiveRecord::Base.connection_pool.checkin(connection_2) connection_3 = ActiveRecord::Base.connection At this point, connection_1 has been removed from the `@reserved_connections` hash, causing a NEW connection to be returned as connection_3 and the loss of any tracking info on connection_1. As long as the thread in this example lives, connection_1 will be inaccessible and un-reapable. If this block of code runs more times than the size of the connection pool in a single thread, every subsequent connection attempt will timeout, as all of the available connections have been leaked. Reverts parts of 9e457a8654fa89fe329719f88ae3679aefb21e56 and essentially all of 4367d2f05cbeda855820e25a08353d4b7b3457ac --- .../connection_adapters/abstract/connection_pool.rb | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb') diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb index 0fa00d03a3..3968b90341 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb @@ -363,7 +363,7 @@ module ActiveRecord conn.expire end - release owner + release conn, owner @available.add conn end @@ -376,7 +376,7 @@ module ActiveRecord @connections.delete conn @available.delete conn - release conn.owner + release conn, conn.owner @available.add checkout_new_connection if @available.any_waiting? end @@ -424,10 +424,12 @@ module ActiveRecord end end - def release(owner) + def release(conn, owner) thread_id = owner.object_id - @reserved_connections.delete thread_id + if @reserved_connections[thread_id] == conn + @reserved_connections.delete thread_id + end end def new_connection -- cgit v1.2.3