IT22398: IBM MQ classes for Java/JMS v9.0 "java.lang.OutOfMemoryError" exception thrown when trace is enabled

APAR status

• Closed as program error.

Error description

• A WebSphere MQ classes for JMS v7.0 application is upgraded to
  use IBM MQ classes for JMS v9.0, and is running the application
  with IBM MQ classes for JMS trace enabled.
  
  The application fails with a "java.lang.OutOfMemoryError" due to
  the JVM's heap space being exhausted, which did not happen when
  using the WebSphere MQ classes for JMS v7.0, despite having the
  same JVM heap size configured.
  
  An FDC is produced of the form:
  
  |  Reason     :-  Data trace threw exception
  |  exception  :-  ExceptionDepth is 2
  |  exception  :-
  |  Cause:1       :-  java.lang.OutOfMemoryError:
                                Java heap space
  |  Message:1     :-  Java heap space
  |  StackTrace:1  :-  java.lang.OutOfMemoryError:
                               Java heap space
  |  at  java.lang.StringBuilder.ensureCapacityImpl
               (StringBuilder.java:366)
  |  at java.lang.StringBuilder.append
               (StringBuilder.java:232)
  |  at com.ibm.msg.client.commonservices.j2se.trace.
              HumanFormatter.format(HumanFormatter.java:279)
  
  The exception is not thrown if the IBM MQ classes for JMS trace
  is not enabled.
  

Local fix

• To prevent the problem from happening, the following JVM
  argument can be provided when the JVM is started:
  
  -Dcom.ibm.msg.client.commonservices.trace.maxBytes=4096
  
  
  Alternatively, the JVM's maximum heap size can be increased to a
  larger value, which can be achieved using the JVM argument:
  
    -Xmx<size>
  
  where <value> is the maximum heap size to use.  For example, if
  the application was running with the 256MB heap size, the
  following command would quadrouple it to 1.0GB:
  
    -Xmx1024M
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects the users of:
  
  - IBM MQ classes for Java v9.0
  - IBM MQ classes for JMS v9.0
  
  who run their application while IBM MQ classes for Java/JMS
  trace is enabled.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When a IBM MQ Classes for Java/JMS application was run with
  trace enabled, a "java.lang.OutOfMemoryError" exception occurred
  and an FDC  file was generated, with the content:
  
  |   Reason     :-  Data trace threw exception
  |   exception  :-  ExceptionDepth is 2
  |   exception  :-
  |   Cause:1       :-  java.lang.OutOfMemoryError: Java
  |   Message:1     :-  Java
  |   StackTrace:1  :-  java.lang.OutOfMemoryError: Java
  |   at
  java.lang.StringBuilder.ensureCapacityImpl(StringBuilder.java:36
  6)
  |   at java.lang.StringBuilder.append(StringBuilder.java:232)
  |   at
  com.ibm.msg.client.commonservices.j2se.trace.HumanFormatter.form
  at(HumanFormatter.java:279)
  |   at
  java.util.logging.StreamHandler.publish(StreamHandler.java:222)
  |   at
  java.util.logging.FileHandler.publish(FileHandler.java:693)
  |   at java.util.logging.Logger.log(Logger.java:749)
  |   at java.util.logging.Logger.doLog(Logger.java:776)
  |   at java.util.logging.Logger.logp(Logger.java:996)
  |   at
  com.ibm.msg.client.commonservices.j2se.trace.DefaultTracer.trace
  Data(DefaultTracer.java:353)
  |   at
  com.ibm.msg.client.commonservices.trace.Trace.traceDataInternal(
  Trace.java:1266)
  |   at
  com.ibm.msg.client.commonservices.trace.Trace.data(Trace.java:11
  71)
  |   at
  com.ibm.mq.jmqi.internal.JmqiTools.traceApiBufferFromStaticMetho
  d(JmqiTools.java:455)
  |   at
  com.ibm.mq.jmqi.internal.JmqiTools.getMessage(JmqiTools.java:163
  1)
  |   at
  com.ibm.mq.jmqi.remote.api.RemoteFAP.jmqiGet(RemoteFAP.java:7024
  )
  |   at
  com.ibm.mq.ese.jmqi.InterceptedJmqiImpl.jmqiGet(InterceptedJmqiI
  mpl.java:1329)
  |   at com.ibm.mq.ese.jmqi.ESEJMQI.jmqiGet(ESEJMQI.java:603)
  |   at
  com.ibm.mq.MQDestination.internalGetMessage(MQDestination.java:1
  041)
  |   at com.ibm.mq.MQDestination.getInt(MQDestination.java:582)
  |   at com.ibm.mq.MQDestination.get(MQDestination.java:448)
  
  
  The "java.lang.OutOfMemoryError" was thrown because the
  application has consumed a number of large messages, and trace
  was attempting to print their entire payload ByteBuffer content
  into the trace file.  The JVM was not able to allocate the
  required amount of memory which the tracing component was
  requesting, resulting in the exception being thrown.
  

Problem conclusion

• IBM MQ classes for Java/JMS have been updated so that by
  default, only the first 4096 bytes of the message payload is
  written out to the trace file, which significantly reduces the
  addition memory overhead requirements of tracing large messages.
  
  This default value can be altered through the use of the JVM
  property:
  
    com.ibm.msg.client.commonservices.trace.maxBytes
  
  
  For example, to write out up to 8KB of the message payload, the
  following JVM argument could be used when the JVM is started:
  
  -Dcom.ibm.msg.client.commonservices.trace.maxBytes=8192
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 CD    9.0.5
  v9.0 LTS   9.0.0.4
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

Temporary fix

Comments

APAR Information

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

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

Fix information

• Fixed component name

  IBM MQ BASE M/P

• Fixed component ID

  5724H7261

Applicable component levels