PQ84327: A NULLPOINTEREXCEPTION FROM THE SELECTIONMANAGER.POPSERVERFORINVOCATION METHOD IS THROWN UNDER HEAVY WORKLOADS | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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APAR status Closed as program error. Error description WebSphere 5.0.1. Under heavy workloads, a NullPointerException or ConcurrentModificationException is thrown from a WeakHashmap object in the Workload Management code. The exception may look something like this: Root exception is java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread Thread-7,5, at java.util.HashMap.onExit(HashMap.java:175) at java.util.HashMap.rehash(HashMap.java:347) at java.util.HashMap.put(HashMap.java:418) at java.util.WeakHashMap.put(WeakHashMap.java:298) at com.ibm.ws.wlm.client.selection.SelectionManager. pushServerForInvocat at com.ibm.ws.wlm.client.selection.SelectionManager. getTarget(SelectionM . This problem may also be seen with a threaddump. You will see m any threads in the following code: . "Thread-18628" daemon prio=5 tid=0x14a6528 nid=0x4bf5 runnable [0x193fe000..0x193ffc68] at java.util.HashMap.get(HashMap.java:263) at java.util.WeakHashMap.get(WeakHashMap.java:260) at com.ibm.ws.wlm.client.selection.SelectionManager.getTarget (SelectionManager.java:139) at com.ibm.ws.wlm.client.WLMClient.getNextTarget(WLMClient.java:Local fix Problem summary **************************************************************** * USERS AFFECTED: WebSphere Application Server users of WLM, * * or Workload Management. * **************************************************************** * PROBLEM DESCRIPTION: Under heavy workloads, a * * NullPointerException or * * ConcurrentModificationException is * * thrown from a WeakHashmap object in * * the Workload Managment code. * **************************************************************** * RECOMMENDATION: * **************************************************************** Under heavy workloads, a NullPointerException or ConcurrentModificationException is thrown from a WeakHashmap object in the Workload Management code. The exception may look something like this: Root exception is java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread Thread-7,5, at java.util.HashMap.onExit(HashMap.java:175) at java.util.HashMap.rehash(HashMap.java:347) at java.util.HashMap.put(HashMap.java:418) at java.util.WeakHashMap.put(WeakHashMap.java:298) at com.ibm.ws.wlm.client.selection.SelectionManager. pushServerForInvocat at com.ibm.ws.wlm.client.selection.SelectionManager. getTarget(SelectionM ... ...Problem conclusion A synchronization block was needed to be placed around the WeakHashmap in question.Temporary fix There is no temporary fix for this problem.Comments
APAR is sysrouted FROM one or more of the following: APAR is sysrouted TO one or more of the following: Modules/Macros
Publications Referenced
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Product categories: Software > Application Servers >
Distributed Application & Web Servers > WebSphere Application
Server > General
Operating system(s):
Software version: 00S
Software edition:
Reference #: PQ84327
IBM Group: Software Group
Modified date: Apr 27, 2004
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