[AMQ-5787] VMTransport uses broken double checked locking

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 5.11.1
• Fix Version/s: 5.11.2, 5.12.0
• Component/s: Broker, Transport
• Assignee: Timothy A. Bish
• Reporter: james
• Created: 20/May/15 18:21
• Updated: 04/Aug/15 12:51
• Resolved: 20/May/15 19:12

Description

the VMTransport.getMessageQueue() method uses the "double checked locking" idiom to avoid the synchronization overhead if the messageQueue has already been instantiated. however, this idiom is broken unless the reference is marked as volatile.