Logger和Appender之间发生Log4j死锁

时间：2011-08-23 07:18:18

标签： log4j deadlock

我正在使用一个LogAppender类，该类扩展了Console Appender，并在内部使用Sendmail函数发送邮件，如果日志级别为ERROR。 （我知道我本可以使用SMPT appender进行邮件发送，但这就是基础设施是如此，请避免对此进行任何评论。）

我的应用程序分为不同的线程，下面提到的问题偶尔发生。（但有些观察告诉我，这可能是由于一个线程需要更多时间来进行初始化）。

我在jstack中获得以下转储：

    "pool-68-thread-1":
  waiting to lock Monitor@0x0000000005496818 (Object@0xfffffd7e390328b0, a crazycode/api/core/common/log/LogAppender),
  which is held by "main"
"main":
  waiting to lock Monitor@0x00000000064dbfc0 (Object@0xfffffd7dfb1f8908, a org/apache/log4j/Logger),
  which is held by "pool-68-thread-1"

Found a total of 1 deadlock.

Thread t@328: (state = BLOCKED)
 - org.apache.log4j.Category.callAppenders(org.apache.log4j.spi.LoggingEvent) @bci=13, line=202 (Interpreted frame)
 - org.apache.log4j.Category.forcedLog(java.lang.String, org.apache.log4j.Priority, java.lang.Object, java.lang.Throwable) @bci=14, line=388 (Interpreted frame)
 - org.apache.log4j.Category.log(java.lang.String, org.apache.log4j.Priority, java.lang.Object, java.lang.Throwable) @bci=34, line=853 (Compiled frame)
 - crazycode.team2Api.common.logging.DESLogger.debug(java.lang.Object) @bci=12, line=240 (Interpreted frame)
 - crazycode.api.core.cache.management.CacheFiller.refreshCache(java.util.List, java.lang.Object, java.lang.String) @bci=33, line=229 (Interpreted frame)
 - crazycode.api.core.cache.management.CacheFiller.initialize(java.lang.Object) @bci=70, line=285 (Interpreted frame)
 - crazycode.api.alert.impl.service.ResearchAlertConfigCacheImpl.init() @bci=18, line=110 (Interpreted frame)
 - crazycode.api.alert.impl.service.ResearchAlertConfigCacheImpl.initialize() @bci=1, line=98 (Interpreted frame)
 - crazycode.api.alert.handler.MemoHandler.initRealHandler() @bci=4, line=573 (Interpreted frame)
 - crazycode.api.alert.handler.RealAlertCoordinator.initHandler(crazycode.api.alert.handler.AlertHandler, int, int, boolean, boolean) @bci=61, line=47 (Interpreted frame)
 - crazycode.api.alert.handler.run.BaseAlertHandlerRun$1$1.run() @bci=72, line=229 (Interpreted frame)
 - java.util.concurrent.Executors$RunnableAdapter.call() @bci=4, line=441 (Interpreted frame)
 - java.util.concurrent.FutureTask$Sync.innerRun() @bci=30, line=303 (Interpreted frame)
 - java.util.concurrent.FutureTask.run() @bci=4, line=138 (Interpreted frame)
 - java.util.concurrent.ThreadPoolExecutor$Worker.runTask(java.lang.Runnable) @bci=59, line=886 (Interpreted frame)
 - java.util.concurrent.ThreadPoolExecutor$Worker.run() @bci=28, line=908 (Interpreted frame)
 - java.lang.Thread.run() @bci=11, line=662 (Interpreted frame)


Thread t@327: (state = BLOCKED)
 - org.apache.log4j.Category.callAppenders(org.apache.log4j.spi.LoggingEvent) @bci=13, line=202 (Interpreted frame)
 - org.apache.log4j.Category.forcedLog(java.lang.String, org.apache.log4j.Priority, java.lang.Object, java.lang.Throwable) @bci=14, line=388 (Interpreted frame)
 - org.apache.log4j.Category.log(java.lang.String, org.apache.log4j.Priority, java.lang.Object, java.lang.Throwable) @bci=34, line=853 (Compiled frame)
 - crazycode.team2Api.common.logging.DESLogger.debug(java.lang.Object) @bci=12, line=240 (Interpreted frame)
 - crazycode.api.core.cache.management.CacheFiller.refreshCache(java.util.List, java.lang.Object, java.lang.String) @bci=33, line=229 (Interpreted frame)
 - crazycode.api.core.cache.management.CacheFiller.initialize(java.lang.Object) @bci=70, line=285 (Interpreted frame)
 - crazycode.api.alert.impl.service.ResearchAlertConfigCacheImpl.init() @bci=18, line=110 (Interpreted frame)
 - crazycode.api.alert.impl.service.ResearchAlertConfigCacheImpl.initialize() @bci=1, line=98 (Interpreted frame)
 - crazycode.api.alert.handler.ResearchDocumentHandler.initRealHandler() @bci=86, line=957 (Interpreted frame)
 - crazycode.api.alert.handler.RealAlertCoordinator.initHandler(crazycode.api.alert.handler.AlertHandler, int, int, boolean, boolean) @bci=61, line=47 (Interpreted frame)
 - crazycode.api.alert.handler.run.BaseAlertHandlerRun$1$1.run() @bci=72, line=229 (Interpreted frame)
 - java.util.concurrent.Executors$RunnableAdapter.call() @bci=4, line=441 (Interpreted frame)
 - java.util.concurrent.FutureTask$Sync.innerRun() @bci=30, line=303 (Interpreted frame)
 - java.util.concurrent.FutureTask.run() @bci=4, line=138 (Interpreted frame)
 - java.util.concurrent.ThreadPoolExecutor$Worker.runTask(java.lang.Runnable) @bci=59, line=886 (Interpreted frame)
 - java.util.concurrent.ThreadPoolExecutor$Worker.run() @bci=28, line=908 (Interpreted frame)
 - java.lang.Thread.run() @bci=11, line=662 (Interpreted frame)


Thread t@322: (state = BLOCKED)
 - org.apache.log4j.Category.callAppenders(org.apache.log4j.spi.LoggingEvent) @bci=13, line=202 (Interpreted frame)
 - org.apache.log4j.Category.forcedLog(java.lang.String, org.apache.log4j.Priority, java.lang.Object, java.lang.Throwable) @bci=14, line=388 (Interpreted frame)
 - org.apache.log4j.Category.log(java.lang.String, org.apache.log4j.Priority, java.lang.Object, java.lang.Throwable) @bci=34, line=853 (Compiled frame)
 - crazycode.team2Api.common.logging.DESLogger.debug(java.lang.Object) @bci=12, line=240 (Interpreted frame)
 - crazycode.api.core.cache.management.CacheFiller.refreshCache(java.util.List, java.lang.Object, java.lang.String) @bci=33, line=229 (Interpreted frame)
 - crazycode.api.core.cache.management.CacheFiller.initialize(java.lang.Object) @bci=70, line=285 (Interpreted frame)
 - crazycode.api.alert.impl.service.ResearchAlertConfigCacheImpl.init() @bci=18, line=110 (Interpreted frame)
 - crazycode.api.alert.impl.service.ResearchAlertConfigCacheImpl.initialize() @bci=1, line=98 (Interpreted frame)
 - crazycode.api.alert.handler.RkdResearchDocumentHandler.initRealHandler() @bci=86, line=779 (Interpreted frame)
 - crazycode.api.alert.handler.RealAlertCoordinator.initHandler(crazycode.api.alert.handler.AlertHandler, int, int, boolean, boolean) @bci=61, line=47 (Interpreted frame)
 - crazycode.api.alert.handler.run.BaseAlertHandlerRun$1$1.run() @bci=72, line=229 (Interpreted frame)
 - java.util.concurrent.Executors$RunnableAdapter.call() @bci=4, line=441 (Interpreted frame)
 - java.util.concurrent.FutureTask$Sync.innerRun() @bci=30, line=303 (Interpreted frame)
 - java.util.concurrent.FutureTask.run() @bci=4, line=138 (Interpreted frame)
 - java.util.concurrent.ThreadPoolExecutor$Worker.runTask(java.lang.Runnable) @bci=59, line=886 (Interpreted frame)
 - java.util.concurrent.ThreadPoolExecutor$Worker.run() @bci=28, line=908 (Interpreted frame)
 - java.lang.Thread.run() @bci=11, line=662 (Interpreted frame)

有人可以解释可能存在的问题以及解决问题的方法是什么？

2 个答案:

答案 0 :(得分：6)

我今天在自己的代码中看到了类似的痕迹。也许它也适用于你？

要点：

  • 之前（死锁）：logger.info(x);（其中x是一个复杂的对象，在toString()内获取读锁定）
  • 之后（ok）：logger.info(x.toString());

详细说明：

在一个线程中，我调用logger.info(x)，调用Category.callAppenders(LoggingEvent)，它在appender上同步，然后调用x.toString()，x试图获取x上的读锁定阻止。

在另一个线程中，我有一个方法在调用logger.info("") callAppenders时保持写锁定，同时调用Thread One [WAITING] sun.misc.Unsafe.park(native method) java.util.concurrent.locks.LockSupport.park(LockSupport.java:158) java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:811) java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireShared(AbstractQueuedSynchronizer.java:941) java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireShared(AbstractQueuedSynchronizer.java:1261) (... my ReadWriteLock$ReadLock.lock(Lock.java:256)) (... my Object's toString() ...) org.apache.log4j.or.DefaultRenderer.doRender(DefaultRenderer.java:36) org.apache.log4j.or.RendererMap.findAndRender(RendererMap.java:80) org.apache.log4j.spi.LoggingEvent.getRenderedMessage(LoggingEvent.java:362) org.apache.log4j.xml.XMLLayout.format(XMLLayout.java:148) org.apache.log4j.WriterAppender.subAppend(WriterAppender.java:302) org.apache.log4j.WriterAppender.append(WriterAppender.java:160) org.apache.log4j.AppenderSkeleton.doAppend(AppenderSkeleton.java:251) org.apache.log4j.helpers.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:66) org.apache.log4j.Category.callAppenders(Category.java:206) org.apache.log4j.Category.forcedLog(Category.java:391) org.apache.log4j.Category.log(Category.java:856) Log.ndebug(Log.java:965) Thread Two [BLOCKED; waiting to lock org.apache.log4j.Logger@1623f] org.apache.log4j.Category.callAppenders(Category.java:204) org.apache.log4j.Category.forcedLog(Category.java:391) org.apache.log4j.Category.log(Category.java:856) Log.debug(Log.java:820) (.. something that acquires my reentrant ReadWriteLock$WriteLock ...) ，试图在appender上同步并阻塞。以下是跟踪的相关部分：

{{1}}

答案 1 :(得分：0)

是否存在“主”线程和“pool-68-thread-1”线程的堆栈？我会查看堆栈中的第一行，这是每个线程中的代码，以找出可能导致死锁的原因。

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