High CPU due to Richfaces HashMap.get() infinite loop

Solution Verified - Updated

Environment

  • JBoss Enterprise Application Platform (EAP)
  • Richfaces

Issue

  • An application running on a 3 node cluster after running normally for some time, suddenly one node CPU spikes to 80% and stays like that.
  • The threads using CPU have stack traces like the following:
"http-0.0.0.0-8080-1" daemon prio=10 tid=0x00002aaaaf78a000 nid=0x27ff runnable [0x0000000049fae000]
   java.lang.Thread.State: RUNNABLE
     at java.util.HashMap.get(HashMap.java:303)
     at org.ajax4jsf.component.UIDataAdaptor.restoreChildState(UIDataAdaptor.java:965)
     at org.ajax4jsf.component.UIDataAdaptor.restoreChildState(UIDataAdaptor.java:984)
     at org.ajax4jsf.component.UIDataAdaptor.restoreChildState(UIDataAdaptor.java:943)
     at org.ajax4jsf.component.UIDataAdaptor.setRowKey(UIDataAdaptor.java:361)
     at org.ajax4jsf.component.UIDataAdaptor.iterate(UIDataAdaptor.java:1029)
     at org.ajax4jsf.component.UIDataAdaptor.encodeAjaxChild(UIDataAdaptor.java:496)
...

Resolution

  • The fix has been applied to the latest Richfaces supported version of 3.3.1.SP2 which can be downloaded from This content is not included.JBoss Web Framework Kit 1.1.0 in the Customer Support Portal
  • A workaround is to enable state serialization as follows in the web deployment descriptor web.xml :
 <context-param>
    <param-name>org.ajax4jsf.SERIALIZE_SERVER_STATE</param-name>
    <param-value>true</param-value>
 </context-param>
  • There is a performance cost for enabling state serialization which may or may not be acceptable.

Root Cause

Diagnostic Steps

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