PK20404: WEBCOMPONENTMETADATAIMPL GENERATES A NEW INSTANCE OF WSTHREADLOCAL WHICH WILL CAUSE A MEMORY LEAK

PK20404; 6.0.2.7: webcomponentmetadataimpl generates a new WSThreadLocal

APAR status

• Closed as program error.

Error description

• A slow memory leak can occur when WebComponentMetaDataImpl
  generates to many WSThreadLocal objects
  .
  java.lang.Exception: WSThreadLocal: instance count = 200 ;
  potential memory leak; verify usage.
          at
  com.ibm.ws.util.WSThreadLocal.<init>(WSThreadLocal.java:61)
          at
  com.ibm.ws.threadContext.ThreadContextImpl.<init>(ThreadContextI
  mpl.java:50)
          at
  com.ibm.ws.webcontainer.metadata.WebComponentMetaDataImpl.<init>
  (WebComponentMetaDataImpl.java:75)
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Websphere application server version 6.0.2.x *
  *                 users who create servlets on the fly,        *
  *                 typically users of JSPs or                   *
  *                 serveServletsByClassName feature.            *
  ****************************************************************
  * PROBLEM DESCRIPTION: A warning that a potential memory leak  *
  *                      may be occurring is written to the      *
  *                      logs. A large number of WSThreadLocal   *
  *                      objects are on the heap.                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  *                                                              *
  ****************************************************************
  A slow memory leak can occur when the webcontainer component
  improperly generates to many WSThreadLocal objects during the
  fly creation of servlets.
  .
  This is characterized by an FFDC log containing a
  java.lang.Exception and including, for example:
  key = java.lang.Exception
  com.ibm.ws.threadContext.ThreadContextImpl 50
  Exception = java.lang.Exception
  Source = com.ibm.ws.threadContext.ThreadContextImpl
  probeid = 50
  Stack Dump = java.lang.Exception: WSThreadLocal: instance count
  = 200 ; potential memory leak; verify usage.
       at
  com.ibm.ws.util.WSThreadLocal.<init>(WSThreadLocal.java:61)
       at
  com.ibm.ws.threadContext.ThreadContextImpl.<init>(ThreadContextI
  mpl.java:50)
       at
  com.ibm.ws.webcontainer.metadata.WebComponentMetaDataImpl.<init>
  (WebComponentMetaDataImpl.java:75)
       at
  com.ibm.ws.webcontainer.metadata.WebMetaDataFactory.createWebCom
  ponentMetaData(WebMetaDataFactory.java:89)
       at
  com.ibm.wsspi.webcontainer.extension.WebExtensionProcessor.creat
  eConfig(WebExtensionProcessor.java:139)
       at
  com.ibm.ws.jsp.webcontainerext.JSPExtensionProcessor.getConfig(J
  SPExtensionProcessor.java:414)
       at
  com.ibm.ws.jsp.webcontainerext.JSPExtensionProcessor.findWrapper
  (JSPExtensionProcessor.java:248)
       at
  com.ibm.ws.jsp.webcontainerext.JSPExtensionProcessor.handleReque
  st(JSPExtensionProcessor.java:239)
  

Problem conclusion

• This problem has been resolved by synchronizing the
  WSThreadLocal object creation with respect to threads.
  
  This fix is tenatively targeted for 6.0.2.13.
  Please refer to
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  for further information
  

Temporary fix

• Sent to the customer
  

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  PK23024

Modules/Macros

• WEBENG
  

Fix information

• Fixed component name

  WEBS APP SERV N

• Fixed component ID

  5724H8800

Applicable component levels

• R60A PSY

     UP

• R60H PSY

     UP

• R60I PSY

     UP

• R60P PSY

     UP

• R60S PSY

     UP

• R60W PSY

     UP

• R60Z PSY

     UP