[jboss-remoting-issues] [JBoss JIRA] Created: (JBREM-1297) Deadlock between MicroRemoteClientInvoker.establishLease and Client.notifyListeners

[Artur Karpinski (JIRA)]

Deadlock between MicroRemoteClientInvoker.establishLease and Client.notifyListeners
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                 Key: JBREM-1297
                 URL: https://issues.jboss.org/browse/JBREM-1297
             Project: JBoss Remoting
          Issue Type: Bug
      Security Level: Public (Everyone can see)
    Affects Versions: 2.5.4.SP2
            Reporter: Artur Karpinski
            Priority: Critical


Deadlock is probably caused by changes introduced in this fix: JBREM-1242.

Thread A:
1. MicroRemoteClientInvoker.terminateLease, locks clientLeaseLock
2. Client.notifyListeners, locks connectionValidatorLock

Thread B:
1. Client.setupClientLease, locks connectionValidatorLock
2. MicroRemoteClientInvoker.establishLease, locks connectionValidatorLock

Please check stacktraces when this deadlock occurred:

{code}
"Timer-16" - Thread t at 486453
   java.lang.Thread.State: BLOCKED
	at org.jboss.remoting.Client.notifyListeners(Client.java:1873)
	- waiting to lock <747c39d3> (a java.lang.Object) owned by "WorkManager(2)-241" t at 6121
	at org.jboss.remoting.LeasePinger.stopPing(LeasePinger.java:134)
	at org.jboss.remoting.MicroRemoteClientInvoker.terminateLease(MicroRemoteClientInvoker.java:434)
	- locked <751714e> (a java.lang.Object)
	at org.jboss.remoting.ConnectionValidator$WaitOnConnectionCheckTimerTask.run(ConnectionValidator.java:1081)
	at java.util.TimerThread.mainLoop(Timer.java:512)
	at java.util.TimerThread.run(Timer.java:462)
{code}

and

{code}
"WorkManager(2)-241" - Thread t at 6121
   java.lang.Thread.State: BLOCKED
	at org.jboss.remoting.MicroRemoteClientInvoker.establishLease(MicroRemoteClientInvoker.java:507)
	- waiting to lock <751714e> (a java.lang.Object) owned by "Timer-16" t at 486453
	at org.jboss.remoting.Client.setupClientLease(Client.java:2056)
	- locked <747c39d3> (a java.lang.Object)
	at org.jboss.remoting.Client.connect(Client.java:1918)
	at org.jboss.remoting.Client.connect(Client.java:737)
{code}

One way to fix this would be to add lock on connectionValidatorLock in MicroRemoteClientInvoker.terminateLease. I'm trying to analyse code to check if this fix will not introduce another deadlock problem.

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