[QPID-2507] C++ broker can deadlock when processing a bind.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.7
• Component/s: C++ Broker

Environment

c++ broker on linux.

• Assignee: Ken Giusti
• Reporter: Ken Giusti
• Created: 14/Apr/10 19:21
• Updated: 29/Jul/13 18:52
• Resolved: 10/Jun/10 18:51

Description

Rarely happens, but I was lucky enough to catch this on the debugger.

Broker locks due to lock inversion. Here's the flow:

thread 1 (broker):
1) gets bind request for the management topic exchange
2) binds to the management topic exchange [takes topic->lock]
3) attempts to call management agent allocId() [takes mgmt agent->userLock]

At the same time:

thread 4 (mgmt agent periodic timer)
1) periodic processing [takes mgmt agent->userLock]
2) call topicexchange::route() [takes topic->lock]

thread one holds the topic->lock, tries to take mgmt agent->userLock
thread four holds mgmt agent->userLock, tries to take topic->lock

deadlock.