我正在编写一个Java应用程序来路由大量并发消息。该应用程序使用Logback框架进行日志记录,我看到应用程序挂起的令人惊讶的行为。在堆栈跟踪中,我可以看到应用程序线程卡在日志记录调用中:
"New I/O client worker #1-1" #125 prio=5 os_prio=0 tid=0x00007f0524017000 nid=0x29f3 waiting on condition [0x00007f052ecea000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00007f089c4a7e88> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
at java.util.concurrent.ArrayBlockingQueue.remainingCapacity(ArrayBlockingQueue.java:468)
at ch.qos.logback.core.AsyncAppenderBase.isQueueBelowDiscardingThreshold(AsyncAppenderBase.java:152)
at ch.qos.logback.core.AsyncAppenderBase.append(AsyncAppenderBase.java:144)
at ch.qos.logback.core.UnsynchronizedAppenderBase.doAppend(UnsynchronizedAppenderBase.java:84)
at ch.qos.logback.core.spi.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:51)
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:421)
at ch.qos.logback.classic.Logger.filterAndLog_0_Or3Plus(Logger.java:383)
at ch.qos.logback.classic.Logger.info(Logger.java:579)
at com.application.ClientListener$6.operationComplete(***.java:514)
- locked <0x00007f089c372b60> (a com.application.ClientListener)
at org.jboss.netty.channel.DefaultChannelFuture.notifyListener(DefaultChannelFuture.java:381)
at org.jboss.netty.channel.DefaultChannelFuture.notifyListeners(DefaultChannelFuture.java:372)
at org.jboss.netty.channel.DefaultChannelFuture.setSuccess(DefaultChannelFuture.java:316)
at org.jboss.netty.channel.socket.nio.NioWorker$RegisterTask.run(NioWorker.java:776)
at org.jboss.netty.channel.socket.nio.NioWorker.processRegisterTaskQueue(NioWorker.java:257)
at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:199)
at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
at org.jboss.netty.util.internal.IoWorkerRunnable.run(IoWorkerRunnable.java:46)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Locked ownable synchronizers:
- <0x00007f08a80fc118> (a java.util.concurrent.ThreadPoolExecutor$Worker)
似乎阻止了日志调用,试图在<0x00007f089c4a7e88>
中使用的java.util.concurrent.ArrayBlockingQueue
实例中获取锁定AsyncAppenderBase
。
在堆栈跟踪中,我可以看到锁<0x00007f089c4a7e88>
由空闲的线程池中的另一个线程持有:
"dispatcher-3" #90 prio=5 os_prio=0 tid=0x00007f04d0004800 nid=0x29d2 waiting on condition [0x00007f0534ed3000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00007f089cbbaae8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1081)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Locked ownable synchronizers:
- <0x00007f089c4a7e88> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
它看起来像ArrayBlockingQueue
的内部锁由该线程持有,随后没有被释放。
这里发生了什么? java.util.concurrent.ArrayBlockingQueue
的竞争条件? Logback中的一个错误?
我使用的是Java 8u40和Logback 1.2.1。
你可以使用discardingThreshold'当阻塞队列剩余20%的容量时,它将丢弃TRACE,DEBUG和INFO级别的事件,只保留级别WARN和ERROR的事件'
样品
<appender name="ASYNCFile" class="ch.qos.logback.classic.AsyncAppender">
<queueSize>50</queueSize>
<discardingThreshold>2</discardingThreshold>
<appender-ref ref="fileAppender" />
</appender>