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  1. JDK
  2. JDK-6915662

Throwable.setStackTrace is not thread-safe

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P4
    • Resolution: Duplicate
    • Affects Version/s: 6u12
    • Fix Version/s: 7
    • Component/s: core-libs
    • Labels:
    • Subcomponent:
    • CPU:
      x86
    • OS:
      windows_xp

      Description

      FULL PRODUCT VERSION :
      java version "1.6.0_12"
      Java(TM) SE Runtime Environment (build 1.6.0_12-b04)
      Java HotSpot(TM) Client VM (build 11.2-b01, mixed mode, sharing)

      ADDITIONAL OS VERSION INFORMATION :
      Windows XP Professional - Version 2002 - Service Pack 2

      A DESCRIPTION OF THE PROBLEM :
      Throwable class is not thread safe regarding private StackTraceElement[] stackTrace field.

      Can be modified concurrently by two threads causing ArrayIndexOutOfBoundsException.

      Two places of modification:

      1) setStackTrace
          public void setStackTrace(StackTraceElement[] stackTrace) {
              ....
              this.stackTrace = defensiveCopy;
          }

      2) getOurStackTrace
          private synchronized StackTraceElement[] getOurStackTrace() {
              // Initialize stack trace if this is the first call to this method
              if (stackTrace == null) {
                  int depth = getStackTraceDepth();
                  stackTrace = new StackTraceElement[depth];
                  for (int i=0; i < depth; i++)
                      stackTrace[i] = getStackTraceElement(i); // throws ArrayIndexOutOfBoundsException
              }
              return stackTrace;
          }

      Solution: setStackTrace should be synchronized as well

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Run two threads calling on the same Throwable object:
      1) first thread - setStackTrace
      2) second thread - getStackTrace

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      Not exception thrown
      ACTUAL -
      Occasional ArrayIndexOutOfBoundsException

      ERROR MESSAGES/STACK TRACES THAT OCCUR :
      java.lang.ArrayIndexOutOfBoundsException: 65
      at java.lang.Throwable.getOurStackTrace(Throwable.java:592)
      at java.lang.Throwable.printStackTrace(Throwable.java:511)
      at org.apache.log4j.spi.ThrowableInformation.getThrowableStrRep(ThrowableInformation.java:59)
      at org.apache.log4j.spi.LoggingEvent.getThrowableStrRep(LoggingEvent.java:342)
      at org.apache.log4j.WriterAppender.subAppend(WriterAppender.java:304)
      at org.apache.log4j.RollingFileAppender.subAppend(RollingFileAppender.java:236)
      at org.apache.log4j.WriterAppender.append(WriterAppender.java:159)
      at org.apache.log4j.AppenderSkeleton.doAppend(AppenderSkeleton.java:230)
      at org.apache.log4j.helpers.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:65)
      at org.apache.log4j.Category.callAppenders(Category.java:203)
      at org.apache.log4j.Category.forcedLog(Category.java:388)
      at org.apache.log4j.Category.log(Category.java:823)


      REPRODUCIBILITY :
      This bug can be reproduced occasionally.

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              • Assignee:
                mchung Mandy Chung
                Reporter:
                ndcosta Nelson Dcosta (Inactive)
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                • Created:
                  Updated:
                  Resolved:
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