Non-atomic increment operation on volatile field ackBytes in class ClientConsumerImpl ------------------------------------------------------------------------------------- Key: JBMESSAGING-1792 URL: https://jira.jboss.org/jira/browse/JBMESSAGING-1792 Project: JBoss Messaging Issue Type: Bug Components: Messaging Core Affects Versions: 2.0.0.beta4 Environment: OS: Redhat-5 Linux 2.6.18-92.el5 JDK: java version "1.6.0" Java(TM) SE Runtime Environment (build pxi3260sr4-20090219_01(SR4)) IBM J9 VM (build 2.4, J2RE 1.6.0 IBM J9 2.4 Linux x86-32 jvmxi3260-20090215_29883 (JIT enabled, AOT enabled) J9VM - 20090215_029883_lHdSMr JIT - r9_20090213_2028 GC - 20090213_AA) JCL - 20090218_01 Reporter: Daniel Luo In class ClientConsumerImpl, field "ackBytes" is declared as volatile int, in method acknowledge(xxx), ackBytes += message.getEncodeSize(); is seen, which is a three-step (read->modify->write) non-atomic operation. Volatile keyword only guarantees variable visibility, but not atomicity, so statement "ackBytes += message.getEncodeSize();" invoked by multiple threads can result to race condition and incorrect result. It's suggested to use synchronized block to protect "ackBytes += message.getEncodeSize();" or AtomicInteger class from java.util.concurrent package to do atomic increment operation. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: https://jira.jboss.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira