[ https://issues.jboss.org/browse/WFLY-3620?page=com.atlassian.jira.plugin.... ] Stefan Schueffler commented on WFLY-3620: ----------------------------------------- Hmm... you are right - the StdioContext should not lead to any locking. Nevertheless, after some time all available threads are "waiting to lock" as in the stacktrace above. In the example given in this bug-report, our jsp-page "selectStatus.jsp" is doing a System.out.println, which unfortunately was left in the code... The same behavior also gets triggered using org.slf4j. A different location where the "waiting to lock" appears (and results in all threads waiting either in StdioContext as above, or Logmanager as given here) is as follows: {code} "EJB default - 4" prio=10 tid=0x4a1ce400 nid=0x5f5d waiting for monitor entry [0x53c8f000] java.lang.Thread.State: BLOCKED (on object monitor) at org.jboss.logmanager.handlers.WriterHandler.doPublish(WriterHandler.java:59) - waiting to lock <0x5edf6ca0> (a java.lang.Object) at org.jboss.logmanager.ExtHandler.publish(ExtHandler.java:79) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:296) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:304) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:304) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:304) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:304) at org.jboss.logmanager.Logger.logRaw(Logger.java:721) at org.jboss.logmanager.Logger.log(Logger.java:672) at org.jboss.logging.JBossLogManagerLogger.doLogf(JBossLogManagerLogger.java:50) at org.jboss.logging.Logger.logf(Logger.java:2096) at org.jboss.as.ejb3.EjbLogger_$logger.retryingTimeout(EjbLogger_$logger.java:298) at org.jboss.as.ejb3.timerservice.task.TimerTask.retryTimeout(TimerTask.java:215) at org.jboss.as.ejb3.timerservice.task.TimerTask.run(TimerTask.java:176) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask.run(FutureTask.java:262) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:744) at org.jboss.threads.JBossThread.run(JBossThread.java:122) {code} In this example, 49 threads are waiting for this particular mutex/lock object (0x5edf6ca0), and one thread is holding this lock, but apparently never finishes his work and releases the lock. Therefore again, only a "kill -9" and restart recovers. Stacktrace of the one "running, but never finishing" thread: {code} "default task-17" prio=10 tid=0x4cdf6000 nid=0x5eca runnable [0x4a86d000] java.lang.Thread.State: RUNNABLE at java.lang.Throwable.fillInStackTrace(Native Method) at java.lang.Throwable.fillInStackTrace(Throwable.java:783) - locked <0xbeabc168> (a java.io.IOException) at java.lang.Throwable.<init>(Throwable.java:265) at java.lang.Exception.<init>(Exception.java:66) at java.io.IOException.<init>(IOException.java:58) at java.io.FileOutputStream.writeBytes(Native Method) at java.io.FileOutputStream.write(FileOutputStream.java:345) at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82) at java.io.BufferedOutputStream.write(BufferedOutputStream.java:95) - locked <0x5edf6d28> (a java.io.BufferedOutputStream) at java.io.PrintStream.write(PrintStream.java:449) - locked <0x5edf6d08> (a java.io.PrintStream) at org.jboss.logmanager.handlers.UncloseableOutputStream.write(UncloseableOutputStream.java:39) at java.io.FilterOutputStream.write(FilterOutputStream.java:77) at org.jboss.logmanager.handlers.UninterruptibleOutputStream.write(UninterruptibleOutputStream.java:59) at java.io.FilterOutputStream.write(FilterOutputStream.java:125) at org.jboss.logmanager.handlers.UninterruptibleOutputStream.write(UninterruptibleOutputStream.java:87) at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221) at sun.nio.cs.StreamEncoder.implWrite(StreamEncoder.java:282) at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:125) - locked <0x5edf6cd0> (a java.io.OutputStreamWriter) at java.io.OutputStreamWriter.write(OutputStreamWriter.java:207) at java.io.BufferedWriter.flushBuffer(BufferedWriter.java:129) - locked <0x5edf6cd0> (a java.io.OutputStreamWriter) at java.io.BufferedWriter.flush(BufferedWriter.java:253) - locked <0x5edf6cd0> (a java.io.OutputStreamWriter) at org.jboss.logmanager.handlers.WriterHandler.safeFlush(WriterHandler.java:173) at org.jboss.logmanager.handlers.WriterHandler.flush(WriterHandler.java:142) - locked <0x5edf6ca0> (a java.lang.Object) at org.jboss.logmanager.ExtHandler.doPublish(ExtHandler.java:107) at org.jboss.logmanager.handlers.WriterHandler.doPublish(WriterHandler.java:70) - locked <0x5edf6ca0> (a java.lang.Object) at org.jboss.logmanager.ExtHandler.publish(ExtHandler.java:79) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:296) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:304) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:304) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:304) at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:304) at org.jboss.logmanager.Logger.logRaw(Logger.java:721) at org.slf4j.impl.Slf4jLogger.log(Slf4jLogger.java:326) at org.slf4j.impl.Slf4jLogger.log(Slf4jLogger.java:320) at org.slf4j.impl.Slf4jLogger.error(Slf4jLogger.java:311) {code} As a side note: those stack traces here and the one in the original bug report are taken from the same run. Searching for the waiting-to-lock-object from the original bug report (Object 0x5ee0adf8) reveals, that the "running, but never finishing" thread also holds this lock (it holds two locks: the one in LogManager (where all other LogManager-Threads are waiting for), and the one in StdioContext/Printwriter (where all "other" Logger-Threads are waiting for). So it comes down to the question, why this one thread never finishes, and how to avoid that one "never ending logger thread" blows up the whole wildfly process by blocking all other threads... -- This message was sent by Atlassian JIRA (v6.2.6#6264)