[AMQNET-830] Deadlock when closing session and connection

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.8.0
• Component/s: OpenWire
• Assignee: Unassigned
• Reporter: Ludovic Pollet
• Created: 14/Mar/23 16:34
• Updated: 14/Mar/23 16:34

Description

Closing a session in a thread and the connection in another thread will collide and yield to a deadlock.

The thread (18) which closes the connection :

• owns the lock sessions.SyncRoot
• wants the session own lock : mylock
  The thread (20) which closes the session:
• own session's mylock
• wants sessions.SyncRoot to remove itself from sessions
   

  Thread 18:
      [Deadlocked, double-click or press enter to view all thread stacks] (Unknown Source:0)
      [Waiting on lock owned by Thread 20] (Unknown Source:0)
      Apache.NMS.ActiveMQ.dll!Apache.NMS.ActiveMQ.Session.Shutdown() (Unknown Source:0)
      Apache.NMS.ActiveMQ.dll!Apache.NMS.ActiveMQ.Connection.Close() (Unknown Source:0)
      ...
      [Native to Managed Transition] (Unknown Source:0)
  
  Thread 20:
      [Deadlocked, double-click or press enter to view all thread stacks] (Unknown Source:0)
      [Waiting on lock owned by Thread 18] (Unknown Source:0)
      System.Private.CoreLib.dll!System.Collections.ArrayList.SyncArrayList.Remove(object value) (Unknown Source:0)
      Apache.NMS.ActiveMQ.dll!Apache.NMS.ActiveMQ.Connection.RemoveSession(Apache.NMS.ActiveMQ.Session session) (Unknown Source:0)
      Apache.NMS.ActiveMQ.dll!Apache.NMS.ActiveMQ.Session.Shutdown() (Unknown Source:0)
      Apache.NMS.ActiveMQ.dll!Apache.NMS.ActiveMQ.Session.DoClose() (Unknown Source:0)
      Apache.NMS.ActiveMQ.dll!Apache.NMS.ActiveMQ.Session.Close() (Unknown Source:0)
      ...
  

   

I can only test in 1.8.0 version. I didn't see any relevant change in the locking scheme since the 1.8.0 version so I assume this bug is still present in more recent releases

I guess sessions.SyncRoot could be released before calling Shutdown on the session (by copying the content of sessions)