[DERBY-3401] Removing a ConnectionEventListener from a PooledConnection during its connectionClosed() callback causes other ConnectionEventListener callbacks to be missed

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 10.4.1.3
• Fix Version/s: 10.4.2.0, 10.5.1.1
• Component/s: JDBC
• Assignee: Knut Anders Hatlen
• Reporter: Daniel John Debrunner
• Created: 08/Feb/08 20:27
• Updated: 21/Jan/11 17:51
• Resolved: 09/Jun/08 08:37

Description

A ConnectionEventListener should be able to remove itself as a listener during a callback without affecting any other callbacks.

DataSourceTest.subtestPooledRemoveListenerOnClose() tests the scenario but calls to it will be commented out in the fixture testPooledReuseOnClose() (using this bug number).

Issue is that such a remove will modify the eventListener Vector in EmbedPooledConnection while it is being enumerated over.
An idea for a fix would be to first change the Vector over to a new-style collection, such as an implementation of List, then work off a copy of the collection when calling the callbacks. I don't think eventListener needs to be a synchronized collection, its access should be already synchronized on EmbedPooledConnection.

I imagine that a similar issue exists for adding a new callback during callback processing, fixing this bug would fix that issue as well though no tests have been written for the add case.

Issue Links

• is duplicated by: DERBY-3675 ConcurrentModificationException on closing pooled connection
• is related to: DERBY-3675 ConcurrentModificationException on closing pooled connection