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Date: 18 Oct 2003 17:44:45 -0000
Message-ID: <20031018174445.29187.qmail@nagoya.betaversion.org>
From: bugzilla@apache.org
To: log4j-dev@jakarta.apache.org
Cc: 
Subject: DO NOT REPLY [Bug 23912] New:  -
    AsyncAppender.getBufferSize() is not properly synchronized

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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=23912

AsyncAppender.getBufferSize() is not properly synchronized

           Summary: AsyncAppender.getBufferSize() is not properly
                    synchronized
           Product: Log4j
           Version: 1.2
          Platform: Other
        OS/Version: Other
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: Appender
        AssignedTo: log4j-dev@jakarta.apache.org
        ReportedBy: aarong@cs.cmu.edu


The method getBufferSize in AsyncAppender acquire the lock on the BoundedFIFO
object before invoking getMaxSize() on it.  In general, the BoundedFIFO class
requires that clients of the class acquire the lcok on the object before
invoking its methods.  The one exception is the method resize(), which is
already declared to be synchronized.  This mixing of conventions is confusing in
general.

In this case, there isn't any real damage that can be caused by this
unsynchronized access to the BoundedFIFO object, but the access does appear to
violate the intended usage convention and thus can be cause further confusion
down the road.

In summary, change AsyncAppender.getBufferSize() to be:

  public int getBufferSize() {
    synchronized( bf ) {
      return bf.getMaxSize();
    }
  }

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