OutOfMemory exception and the portal was not accessible. Restarting the server resolved the issue

• Type: Bug
• Status: Closed
• Resolution: No Longer Reproducible
• Affects Version/s: 6.1.20 EE GA2
• Fix Version/s: None
• Component/s: Environments, Environments > Java Runtime
• Labels: None
• Epic/Theme:
  • Escalation
• Fix Priority: 3

Issue:

Customer found OutOfMemory exception and the portal was not accessible. Restarting the server resolved the issue, but customer would like to know why this issue happened.

65.18% of Java Heap is used by 483,660 instances of com/liferay/portal/kernel/concurrent/TaskQueue$Node
Contains the following object:
-483,659 instances of com/liferay/portal/kernel/messaging/ParallelDestination$1

Logs and Dumps:https://drive.google.com/a/liferay.com/folderview?id=0B14hdRQ6_GcQdFpDOHhLa3Vjckk&usp=sharing#