[logback-dev] IllegalMonitorStateException in AppenderAttachableImpl.appendLoopOnAppenders()

[Szel, Zoltan (IDEAS)]

Hi,

We have hit the exception mentioned in the subject in one of our applications. We are using JDK 6 and Logback 0.9.14.  Here is the stacktrace:
Caused by: java.lang.IllegalMonitorStateException
 at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.tryReleaseShared(ReentrantReadWriteLock.java:363)
 at java.util.concurrent.locks.AbstractQueuedSynchronizer.releaseShared(AbstractQueuedSynchronizer.java:1253)
 at java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.unlock(ReentrantReadWriteLock.java:745)
 at ch.qos.logback.core.spi.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:64)
 at ch.qos.logback.classic.Logger.appendLoopOnAppenders(Logger.java:270)
 at ch.qos.logback.classic.Logger.callAppenders(Logger.java:257)
 at ch.qos.logback.classic.Logger.buildLoggingEventAndAppend(Logger.java:439)
 at ch.qos.logback.classic.Logger.filterAndLog_1(Logger.java:411)
 at ch.qos.logback.classic.Logger.debug(Logger.java:504)

I have checked the code and it seems to me this can only happen if the readLock.lock() method throws an exception:

public int appendLoopOnAppenders(E e) {

56<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#56>      int size = 0;

57<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#57>      try {

58<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#58>        r.lock();

59<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#59>        for (Appender<E> appender : appenderList) {

60<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#60>          appender.doAppend(e);

61<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#61>          size++;

62<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#62>        }

63<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#63>      } finally {

64<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#64>        r.unlock();

65<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#65>      }

66<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#66>      return size;

67<http://logback.qos.ch/xref/ch/qos/logback/core/spi/AppenderAttachableImpl.html#67>    }

if r.lock() in line 58 throws an exception for some reason than in the finally block the unlock will throw also an exception which will hide the original one. I cannot see any other reason why the unlock would throw this exception in this scenario. I am not yet able to reproduce it, but I thought this exception worth a mail. The only suggestion I have for now is to move the r.lock() call out of the try block, because if that is the bad guy, than we would have the original exception propagated.

If I have more information on this issue I will update this thread.

Regards,
Zoltan Szel
Morgan Stanley | IDEAS PRACTICE AREAS
Lechner Odon fasor 8 | Floor 07
Budapest, 1095
Phone: +36 1 881-3978
Zoli.Szel at MorganStanley.com<mailto:Zoli.Szel at MorganStanley.com>
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