zoukankan html css js c++ java

Java线程和多线程（八）——Thread Dump

Java的Thread Dump就是列出JVM中所有激活状态的线程。

Java Thread Dump

Java Thread Dump在分析应用性能瓶颈和死锁的时候，是非常有效的。

下面将介绍多种不同的方式来获取Java程序的Thread Dump信息。这些指令在*nix型的操作系统下是有效的，但是在Windows下面，采取的方式会有一些不同。（主要是Pid信息获取不太一致，可通过任务管理器获取）

VisualVM Profiler：如果开发者需要分析程序变慢的原因，那么必然要使用profiler。我们可以通过VisulaVM Profiler工具很容易的从运行的线程获取Thread Dump。你所需要的就是右键运行的进行，然后点击Thread Dump来获得这个信息。
jstack：Java本身就自带的jstack工具，我们可以通过Java线程来直接生成Thread Dump。
1. 受限找到Java进程的PID，可以通过ps -eaf | grep java命令来获取。
2. 然后运行jstack工具，jstack PID来生成Thread Dump到控制台，当然，也可以通过重定向，将Thread Dump信息的输出通过命令jstack PID >> thread.dump写入thread.dump这个文本当中。
我们可以通过kill -3 PID命令来生成Thread Dump信息。这种方式和其它的生成Thread Dump的方式略有不同，当执行了kill命令的时候，Thread Dump信息会直接输出到控制台。所以，如果Java程序的System.out是控制台的话，Thread Dump的信息就会打印到控制台。如果Java的程序时一个Tomcat的服务程序，System.out将变成catalina.out文件，那时，Thread Dump会打印到catalina.out这个文件之中。
Java 8引入了jcmd工具箱，开发者如果使用的是Java 8或者更高的版本的话，可以用之来替换掉jstack。命令行与jstack很类似：jcmd PID Thread.print。

上面的四种方式都可以用来在Java中生成Thread Dump的信息。通常，我推荐使用jstack或者jcmd命令来生成Thread Dump信息来分析。当然，无论你使用什么样的方式，最后的Thread Dump的信息都是一样的。

Java Thread Dump举例

我将自己写的一个Tomcat程序运行Thread Dump，结果如下：

$ jcmd 4428 Thread.print
4428:
2016-09-27 22:42:29
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.65-b01 mixed mode):

"ajp-nio-8009-AsyncTimeout" #39 daemon prio=5 os_prio=0 tid=0x000000001d4c4000 nid=0x34c4 waiting on condition [0x000000002ca1f000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at org.apache.coyote.AbstractProtocol$AsyncTimeout.run(AbstractProtocol.java:1080)
        at java.lang.Thread.run(Thread.java:745)

"ajp-nio-8009-Acceptor-0" #38 daemon prio=5 os_prio=0 tid=0x000000001d4c6800 nid=0x34c0 runnable [0x000000002c91f000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
        at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422)
        at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250)
        - locked <0x0000000080b2bfb0> (a java.lang.Object)
        at org.apache.tomcat.util.net.NioEndpoint$Acceptor.run(NioEndpoint.java:508)
        at java.lang.Thread.run(Thread.java:745)

"ajp-nio-8009-ClientPoller-1" #37 daemon prio=5 os_prio=0 tid=0x000000001d4c3800 nid=0x34bc runnable [0x000000002c81e000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x00000000829ecd28> (a sun.nio.ch.Util$2)
        - locked <0x00000000829ecd18> (a java.util.Collections$UnmodifiableSet)
        - locked <0x00000000829ecba8> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:843)
        at java.lang.Thread.run(Thread.java:745)

"ajp-nio-8009-ClientPoller-0" #36 daemon prio=5 os_prio=0 tid=0x000000001d4c5800 nid=0x34b8 runnable [0x000000002b72f000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x00000000829ee720> (a sun.nio.ch.Util$2)
        - locked <0x00000000829ee710> (a java.util.Collections$UnmodifiableSet)
        - locked <0x00000000829ee5a0> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:843)
        at java.lang.Thread.run(Thread.java:745)

"http-nio-8080-AsyncTimeout" #35 daemon prio=5 os_prio=0 tid=0x000000001d4c1000 nid=0x34b4 waiting on condition [0x000000002b62f000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at org.apache.coyote.AbstractProtocol$AsyncTimeout.run(AbstractProtocol.java:1080)
        at java.lang.Thread.run(Thread.java:745)

"http-nio-8080-Acceptor-0" #34 daemon prio=5 os_prio=0 tid=0x000000001d4c2800 nid=0x34b0 runnable [0x000000002b52f000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
        at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422)
        at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250)
        - locked <0x0000000080b30a30> (a java.lang.Object)
        at org.apache.tomcat.util.net.NioEndpoint$Acceptor.run(NioEndpoint.java:508)
        at java.lang.Thread.run(Thread.java:745)

"http-nio-8080-ClientPoller-1" #33 daemon prio=5 os_prio=0 tid=0x000000001d4c2000 nid=0x34ac runnable [0x000000002b1de000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x0000000082896118> (a sun.nio.ch.Util$2)
        - locked <0x0000000082896108> (a java.util.Collections$UnmodifiableSet)
        - locked <0x0000000082895f98> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:843)
        at java.lang.Thread.run(Thread.java:745)

"http-nio-8080-ClientPoller-0" #32 daemon prio=5 os_prio=0 tid=0x000000001d4c0800 nid=0x34a8 runnable [0x000000002b0de000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x0000000082896af8> (a sun.nio.ch.Util$2)
        - locked <0x0000000082896ae8> (a java.util.Collections$UnmodifiableSet)
        - locked <0x0000000082896978> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:843)
        at java.lang.Thread.run(Thread.java:745)

"ContainerBackgroundProcessor[StandardEngine[Catalina]]" #31 daemon prio=5 os_prio=0 tid=0x000000001f3d8800 nid=0x34a4 waiting on condition [0x0000000029fce000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1340)
        at java.lang.Thread.run(Thread.java:745)

"pool-2-thread-1" #30 prio=5 os_prio=0 tid=0x000000001f3dc800 nid=0x3498 waiting on condition [0x00000000288df000]
   java.lang.Thread.State: TIMED_WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x0000000082753eb0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
        at java.util.concurrent.ScheduledThreadPoolExecutor$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)

"Timer-0" #29 daemon prio=5 os_prio=0 tid=0x000000001f3d6000 nid=0x3494 in Object.wait() [0x000000002856f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at java.util.TimerThread.mainLoop(Timer.java:552)
        - locked <0x0000000082751430> (a java.util.TaskQueue)
        at java.util.TimerThread.run(Timer.java:505)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_QuartzSchedulerThread" #28 prio=5 os_prio=0 tid=0x000000001f3dd000 nid=0x3490 in Object.wait() [0x000000002846e000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.core.QuartzSchedulerThread.run(QuartzSchedulerThread.java:410)
        - locked <0x0000000082751b28> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-10" #27 prio=5 os_prio=0 tid=0x000000001f3d7800 nid=0x348c in Object.wait() [0x000000002826f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x0000000082717950> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-9" #26 prio=5 os_prio=0 tid=0x000000001f3da000 nid=0x3488 in Object.wait() [0x000000002816f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x0000000082717618> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-8" #25 prio=5 os_prio=0 tid=0x000000001f3db800 nid=0x3484 in Object.wait() [0x000000002806f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x00000000827172e0> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-7" #24 prio=5 os_prio=0 tid=0x000000001f3d9000 nid=0x3480 in Object.wait() [0x0000000027f6f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x0000000082716fa8> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-6" #23 prio=5 os_prio=0 tid=0x000000001f3db000 nid=0x347c in Object.wait() [0x0000000027e6e000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x0000000082716c70> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-5" #22 prio=5 os_prio=0 tid=0x000000001f3d7000 nid=0x3478 in Object.wait() [0x0000000027d6f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x0000000082716938> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-4" #21 prio=5 os_prio=0 tid=0x000000002107b800 nid=0x3474 in Object.wait() [0x0000000027c6f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x0000000082716600> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-3" #20 prio=5 os_prio=0 tid=0x0000000023019000 nid=0x3470 in Object.wait() [0x0000000027b6f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x000000008270fb40> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-2" #19 prio=5 os_prio=0 tid=0x000000001f6a4000 nid=0x346c in Object.wait() [0x000000002721f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x00000000827162b0> (a java.lang.Object)

"org.springframework.scheduling.quartz.SchedulerFactoryBean#0_Worker-1" #18 prio=5 os_prio=0 tid=0x000000001a75a800 nid=0x3468 in Object.wait() [0x000000002014f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
        - locked <0x0000000082715f78> (a java.lang.Object)

"NioBlockingSelector.BlockPoller-2" #15 daemon prio=5 os_prio=0 tid=0x0000000019d0b000 nid=0x2150 runnable [0x000000001b59e000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x0000000080a8c5c8> (a sun.nio.ch.Util$2)
        - locked <0x0000000080a8c5b8> (a java.util.Collections$UnmodifiableSet)
        - locked <0x0000000080a8c448> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at org.apache.tomcat.util.net.NioBlockingSelector$BlockPoller.run(NioBlockingSelector.java:341)

"NioBlockingSelector.BlockPoller-1" #14 daemon prio=5 os_prio=0 tid=0x0000000019d09000 nid=0x890 runnable [0x000000001b49f000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x0000000080b2d2f8> (a sun.nio.ch.Util$2)
        - locked <0x0000000080b2d2e8> (a java.util.Collections$UnmodifiableSet)
        - locked <0x0000000080b2d188> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at org.apache.tomcat.util.net.NioBlockingSelector$BlockPoller.run(NioBlockingSelector.java:341)

"GC Daemon" #13 daemon prio=2 os_prio=-2 tid=0x0000000019e8d800 nid=0x27fc in Object.wait() [0x000000001b17f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x0000000080c322d0> (a sun.misc.GC$LatencyLock)
        at sun.misc.GC$Daemon.run(GC.java:117)
        - locked <0x0000000080c322d0> (a sun.misc.GC$LatencyLock)

"Service Thread" #11 daemon prio=9 os_prio=0 tid=0x0000000018c19000 nid=0x2a78 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread2" #10 daemon prio=9 os_prio=2 tid=0x0000000018bc2800 nid=0x11b8 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread1" #9 daemon prio=9 os_prio=2 tid=0x0000000018bc1800 nid=0x1f90 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #8 daemon prio=9 os_prio=2 tid=0x0000000018bbf800 nid=0x3288 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"JDWP Event Helper Thread" #7 daemon prio=10 os_prio=0 tid=0x0000000018bb2800 nid=0x339c runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"JDWP Transport Listener: dt_socket" #6 daemon prio=10 os_prio=0 tid=0x0000000018ba6800 nid=0x1628 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Attach Listener" #5 daemon prio=5 os_prio=2 tid=0x00000000175cd800 nid=0x1790 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=2 tid=0x000000001761e000 nid=0xa24 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=1 tid=0x0000000002998000 nid=0xb94 in Object.wait() [0x000000001893f000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
        - locked <0x000000008051aa40> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)

"Reference Handler" #2 daemon prio=10 os_prio=2 tid=0x000000000298f000 nid=0x5cc in Object.wait() [0x000000001883f000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:157)
        - locked <0x00000000800cce68> (a java.lang.ref.Reference$Lock)

"main" #1 prio=5 os_prio=0 tid=0x000000000240e000 nid=0x2478 runnable [0x000000000289e000]
   java.lang.Thread.State: RUNNABLE
        at java.net.DualStackPlainSocketImpl.accept0(Native Method)
        at java.net.DualStackPlainSocketImpl.socketAccept(DualStackPlainSocketImpl.java:131)
        at java.net.AbstractPlainSocketImpl.accept(AbstractPlainSocketImpl.java:409)
        at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:199)
        - locked <0x0000000082a8afe0> (a java.net.SocksSocketImpl)
        at java.net.ServerSocket.implAccept(ServerSocket.java:545)
        at java.net.ServerSocket.accept(ServerSocket.java:513)
        at org.apache.catalina.core.StandardServer.await(StandardServer.java:446)
        at org.apache.catalina.startup.Catalina.await(Catalina.java:737)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:683)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:351)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:485)

"VM Thread" os_prio=2 tid=0x0000000017587000 nid=0x1aec runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00000000028b7000 nid=0x1ea0 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00000000028b8800 nid=0x19ac runnable

"GC task thread#2 (ParallelGC)" os_prio=0 tid=0x00000000028ba000 nid=0x2de8 runnable

"GC task thread#3 (ParallelGC)" os_prio=0 tid=0x00000000028bd000 nid=0x540 runnable

"VM Periodic Task Thread" os_prio=2 tid=0x0000000018c46000 nid=0x240c waiting on condition

JNI global references: 6164

Thread Dump会列出全部的线程，每个条目都包含如下的信息：

Thread Name：线程的名字
Thread Priority：线程的优先级
Thread ID：代表线程的ID
Thread Status：表示线程的状态，举例来说就是RUNNABLE，WAITING，BLOCKED等等，当在分析死锁的时候，可以查看阻塞的线程和被请求的资源。
Thread CallStack：提供一个线程至关重要的堆栈信息。这也是我们可以看到线程获取的锁和是否在等待锁等信息。

通过上面这些信息，就能够看到一些程序的线程细节，当程序有一些问题之类，就可以从中找到真正影响性能的地方。

查看全文

相关阅读:
(BFS 二叉树) leetcode 515. Find Largest Value in Each Tree Row
(二叉树 BFS) leetcode513. Find Bottom Left Tree Value
(二叉树 BFS DFS) leetcode 104. Maximum Depth of Binary Tree
(二叉树 BFS DFS) leetcode 111. Minimum Depth of Binary Tree
(BFS) leetcode 690. Employee Importance
(BFS/DFS) leetcode 200. Number of Islands
(最长回文子串线性DP) 51nod 1088 最长回文子串
 (链表 importance) leetcode 2. Add Two Numbers
(链表 set) leetcode 817. Linked List Components
(链表双指针) leetcode 142. Linked List Cycle II

原文地址：https://www.cnblogs.com/qitian1/p/6461524.html