概述

　　有些时候我们需要查看下JVM中的线程执行情况，比如：发现服务器的CPU的负载突然增高了，出现了死锁，死循环等；

　　由于程序是正常运行的，没有任何的输出，从日志方面也看不出问题，所以就需要看下JVM的内部线程的执行情况，然后在进行分析查找出原因；

　　这个时候，就需要借助jstack命令了，jstack的作用是将正在运行的JVM的线程情况进行快照，并且打印出来；

　　使用命令【jstack 进程号】

E:\北大青鸟\Y2\JVM\文件>jstack 17656
2020-03-03 16:54:24
Full thread dump Java HotSpot(TM) Client VM (25.73-b02 mixed mode):

"http-bio-8080-exec-6" #34 daemon prio=5 os_prio=0 tid=0x15535c00 nid=0x33ac waiting on condition [0x16f2f000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x0a270340> (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.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)

"http-bio-8080-exec-5" #33 daemon prio=5 os_prio=0 tid=0x15535800 nid=0x27d0 waiting on condition [0x16e9f000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x0a270340> (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.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)

"http-bio-8080-exec-4" #32 daemon prio=5 os_prio=0 tid=0x15538400 nid=0xa2c waiting on condition [0x16e0f000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x0a270340> (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.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)

"http-bio-8080-exec-3" #31 daemon prio=5 os_prio=0 tid=0x15535000 nid=0x4bf4 waiting on condition [0x16d7f000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x0a270340> (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.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)

"http-bio-8080-exec-2" #30 daemon prio=5 os_prio=0 tid=0x15537400 nid=0x4010 waiting on condition [0x16cef000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x0a270340> (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.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)

"http-bio-8080-exec-1" #29 daemon prio=5 os_prio=0 tid=0x15537000 nid=0x2478 waiting on condition [0x1635f000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x0a270340> (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.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)

"ajp-bio-8009-AsyncTimeout" #26 daemon prio=5 os_prio=0 tid=0x15537c00 nid=0x3ddc waiting on condition [0x162cf000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at org.apache.tomcat.util.net.JIoEndpoint$AsyncTimeout.run(JIoEndpoint.java:152)
        at java.lang.Thread.run(Thread.java:745)

"ajp-bio-8009-Acceptor-0" #25 daemon prio=5 os_prio=0 tid=0x15536800 nid=0x51a0 runnable [0x1623f000]
   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 <0x0a1352a8> (a java.net.SocksSocketImpl)
        at java.net.ServerSocket.implAccept(ServerSocket.java:545)
        at java.net.ServerSocket.accept(ServerSocket.java:513)
        at org.apache.tomcat.util.net.DefaultServerSocketFactory.acceptSocket(DefaultServerSocketFactory.java:60)
        at org.apache.tomcat.util.net.JIoEndpoint$Acceptor.run(JIoEndpoint.java:222)
        at java.lang.Thread.run(Thread.java:745)

"http-bio-8080-AsyncTimeout" #24 daemon prio=5 os_prio=0 tid=0x15538800 nid=0x2390 waiting on condition [0x161af000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at org.apache.tomcat.util.net.JIoEndpoint$AsyncTimeout.run(JIoEndpoint.java:152)
        at java.lang.Thread.run(Thread.java:745)

"http-bio-8080-Acceptor-0" #23 daemon prio=5 os_prio=0 tid=0x154e4000 nid=0x3d3c runnable [0x1611f000]
   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 <0x0a135390> (a java.net.SocksSocketImpl)
        at java.net.ServerSocket.implAccept(ServerSocket.java:545)
        at java.net.ServerSocket.accept(ServerSocket.java:513)
        at org.apache.tomcat.util.net.DefaultServerSocketFactory.acceptSocket(DefaultServerSocketFactory.java:60)
        at org.apache.tomcat.util.net.JIoEndpoint$Acceptor.run(JIoEndpoint.java:222)
        at java.lang.Thread.run(Thread.java:745)

"ContainerBackgroundProcessor[StandardEngine[Catalina]]" #22 daemon prio=5 os_prio=0 tid=0x154e3c00 nid=0x1774 waiting on condition [0x1608f000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1512)
        at java.lang.Thread.run(Thread.java:745)

"GC Daemon" #18 daemon prio=2 os_prio=-2 tid=0x15484800 nid=0x4e2c in Object.wait() [0x15e6f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x0a0dd158> (a sun.misc.GC$LatencyLock)
        at sun.misc.GC$Daemon.run(GC.java:117)
        - locked <0x0a0dd158> (a sun.misc.GC$LatencyLock)

"RMI Scheduler(0)" #14 daemon prio=5 os_prio=0 tid=0x152b4c00 nid=0x617c waiting on condition [0x15aef000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x09dbc780> (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)

"RMI TCP Accept-0" #12 daemon prio=5 os_prio=0 tid=0x151ac400 nid=0x252c runnable [0x1583f000]
   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 <0x09eb9b28> (a java.net.SocksSocketImpl)
        at java.net.ServerSocket.implAccept(ServerSocket.java:545)
        at java.net.ServerSocket.accept(ServerSocket.java:513)
        at sun.management.jmxremote.LocalRMIServerSocketFactory$1.accept(LocalRMIServerSocketFactory.java:52)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:400)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:372)
        at java.lang.Thread.run(Thread.java:745)

"RMI TCP Accept-1099" #11 daemon prio=5 os_prio=0 tid=0x14e50000 nid=0x4c7c runnable [0x156af000]
   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 <0x09eb9e90> (a java.net.SocksSocketImpl)
        at java.net.ServerSocket.implAccept(ServerSocket.java:545)
        at java.net.ServerSocket.accept(ServerSocket.java:513)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:400)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:372)
        at java.lang.Thread.run(Thread.java:745)

"RMI TCP Accept-0" #10 daemon prio=5 os_prio=0 tid=0x15198400 nid=0x5d1c runnable [0x1561f000]
   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 <0x09eba190> (a java.net.SocksSocketImpl)
        at java.net.ServerSocket.implAccept(ServerSocket.java:545)
        at java.net.ServerSocket.accept(ServerSocket.java:513)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:400)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:372)
        at java.lang.Thread.run(Thread.java:745)

"Service Thread" #7 daemon prio=9 os_prio=0 tid=0x14c99c00 nid=0x26f0 runnable [0x00000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread0" #6 daemon prio=9 os_prio=2 tid=0x14c91c00 nid=0x950 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Attach Listener" #5 daemon prio=5 os_prio=2 tid=0x14c91000 nid=0x53e4 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=2 tid=0x14cc6400 nid=0x3710 runnable [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=1 tid=0x14c64800 nid=0x4a8c in Object.wait() [0x14eef000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x09eba9d8> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
        - locked <0x09eba9d8> (a java.lang.ref.ReferenceQueue$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=0x14c63400 nid=0x5984 in Object.wait() [0x047ef000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x09ebab78> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:157)
        - locked <0x09ebab78> (a java.lang.ref.Reference$Lock)

"main" #1 prio=5 os_prio=0 tid=0x0028d400 nid=0x10c4 runnable [0x00d2f000]
   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 <0x0a2e50d8> (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:453)
        at org.apache.catalina.startup.Catalina.await(Catalina.java:777)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:723)
        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:321)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:455)

"VM Thread" os_prio=2 tid=0x00eddc00 nid=0x3378 runnable

"VM Periodic Task Thread" os_prio=2 tid=0x151ad800 nid=0x5988 waiting on condition

JNI global references: 266

View Code

1.线程的状态

　　

　　线程的状态一共分为6种：

　　　　1.初始态（NEW）

　　　　　　创建一个Thread对象，但未调用start()启动线程时，线程处于初始态；

　　　　2.运行态（RUNNABLE）

　　　　　　就绪态

　　　　　　　　该状态下的线程已经获得执行所需要的所以资源，只要CPU分配执行权就能运行；

　　　　　　　　所有就绪的线程存放在就绪队列中；

　　　　　　运行态

　　　　　　　　获得CPU执行权，正在执行的线程；

　　　　　　　　由于一个CPU同一时刻只能执行一条线程，因此每个CPU每个时刻只有一条运行态的线程；

　　　　3.阻塞态（BLOCKED）

　　　　　　当一条正在执行的线程请求某一资源失败时，就会进入阻塞态；

　　　　　　而在java中，阻塞态专指请求锁失败时进入的状态；

　　　　　　由一个阻塞队列存放所有阻塞态的线程；

　　　　　　处于阻塞态的线程会不断请求资源，一旦请求成功，就会进入就绪队列，等待执行；

　　　　4.等待态（WAITING）

　　　　　　当前线程中调用wait，join，park函数时，当前线程就会进入等待状态；

　　　　　　也有一个等待队列存放所有等待态的线程；

　　　　　　线程处于等待态表示它需要等待其他线程的指示才能继续运行；

　　　　　　进入等待态的线程会释放CPU执行权，并释放资源；

　　　　5.超时等待态（TIMED_WAITING）

　　　　　　当运行中的线程调用sleep(time)，wait，join，parkNanos，parkUntil时，就会进入该状态；

　　　　　　它和等待态一样，并不是因为请求不到资源，而是主动进入，并且进入后需要其他线程唤醒；

　　　　　　进入该状态后释放CPU执行权和占有的资源；

　　　　　　与等待态的区别：到了超时时间后自动进入阻塞队列，开始竞争锁；

　　　　6.终止态（TERMINATED）

　　　　　　线程执行结束后的状态；

2.死锁问题

　　如果在生产环境发生了死锁，我们将看到的是部署的程序没有任何反应了，这个时候我们可以借助jstack进行分析；

　　2.1 构造死锁

　　　　编写代码，启动2个线程，Thread1拿到了obj1锁，准备去拿obj2锁时，obj2已经被Thread2锁定，所以发送了死锁；

public class TestDeadLock {
    private static Object obj1=new Object();
    private static Object obj2=new Object();
    public static void main(String[] args){
        new Thread(new Thread1()).start();
        new Thread(new Thread2()).start();
    }
    private static class Thread1 implements Runnable{

        @Override
        public void run() {
            synchronized (obj1){
                System.out.println("Thread1-obj1");
                try {
                    Thread.sleep(2000);
                }catch (InterruptedException e){
                    e.printStackTrace();
                }
                synchronized (obj2){
                    System.out.println("Thread1-obj2");
                }
            }
        }
    }
    private static class Thread2 implements Runnable{

        @Override
        public void run() {
            synchronized (obj2){
                System.out.println("Thread2-obj2");
                try {
                    Thread.sleep(2000);
                }catch (InterruptedException e){
                    e.printStackTrace();
                }
                synchronized (obj1){
                    System.out.println("Thread2-obj1");
                }
            }
        }
    }

}

　　2.2 运行

　　　　使用【javac TestDeadLock.java】命令进行编译

　　　　　　

 　　　　使用【java TestDeadLock】命令执行

E:\北大青鸟\Y2\JVM\文件>java TestDeadLock
Thread1-obj1
Thread2-obj2

　　　　　　注意：这里发生了死锁，程序将一直等待下去；

　　2.3 使用jstack进行分析

E:\北大青鸟\Y2\JVM\文件>jps
15956
16548 Main
22292 RemoteMavenServer
4452
17656 Bootstrap
2536 Jps
10524 Launcher
8828 TestDeadLock

E:\北大青鸟\Y2\JVM\文件>jstack 8828
2020-03-03 17:50:16
Full thread dump Java HotSpot(TM) Client VM (25.73-b02 mixed mode):

"DestroyJavaVM" #10 prio=5 os_prio=0 tid=0x031bc400 nid=0x2628 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Thread-1" #9 prio=5 os_prio=0 tid=0x1588dc00 nid=0x35a4 waiting for monitor entry [0x15f0f000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at TestDeadLock$Thread2.run(TestDeadLock.java:37)
        - waiting to lock <0x052e39d8> (a java.lang.Object)
        - locked <0x052e39e0> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:745)

"Thread-0" #8 prio=5 os_prio=0 tid=0x1588d400 nid=0x2e40 waiting for monitor entry [0x15e7f000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at TestDeadLock$Thread1.run(TestDeadLock.java:20)
        - waiting to lock <0x052e39e0> (a java.lang.Object)
        - locked <0x052e39d8> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:745)

"Service Thread" #7 daemon prio=9 os_prio=0 tid=0x15825400 nid=0x4dec runnable [0x00000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread0" #6 daemon prio=9 os_prio=2 tid=0x157d3800 nid=0x1df0 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Attach Listener" #5 daemon prio=5 os_prio=2 tid=0x157d0000 nid=0x2680 waiting on condition [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=2 tid=0x157cf400 nid=0x2170 runnable [0x00000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=1 tid=0x157a6c00 nid=0x200c in Object.wait() [0x15abf000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x05206458> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
        - locked <0x05206458> (a java.lang.ref.ReferenceQueue$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=0x0310e800 nid=0x17bc in Object.wait() [0x15a2f000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x05205f50> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:157)
        - locked <0x05205f50> (a java.lang.ref.Reference$Lock)

"VM Thread" os_prio=2 tid=0x0310bc00 nid=0x1c18 runnable

"VM Periodic Task Thread" os_prio=2 tid=0x15887400 nid=0x2338 waiting on condition

JNI global references: 6


Found one Java-level deadlock:
=============================
"Thread-1":
  waiting to lock monitor 0x157a56a4 (object 0x052e39d8, a java.lang.Object),
  which is held by "Thread-0"
"Thread-0":
  waiting to lock monitor 0x157a63c4 (object 0x052e39e0, a java.lang.Object),
  which is held by "Thread-1"

Java stack information for the threads listed above:
===================================================
"Thread-1":
        at TestDeadLock$Thread2.run(TestDeadLock.java:37)
        - waiting to lock <0x052e39d8> (a java.lang.Object)
        - locked <0x052e39e0> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:745)
"Thread-0":
        at TestDeadLock$Thread1.run(TestDeadLock.java:20)
        - waiting to lock <0x052e39e0> (a java.lang.Object)
        - locked <0x052e39d8> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:745)

Found 1 deadlock.

　　在输出的信息中，已经看到了，发送一个死锁，关键看这个：

"Thread-1":
        at TestDeadLock$Thread2.run(TestDeadLock.java:37)
        - waiting to lock <0x052e39d8> (a java.lang.Object)
        - locked <0x052e39e0> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:745)
"Thread-0":
        at TestDeadLock$Thread1.run(TestDeadLock.java:20)
        - waiting to lock <0x052e39e0> (a java.lang.Object)
        - locked <0x052e39d8> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:745)

　　可以清晰的看到：

　　　　Thread2获取了<0x052e39e0>的锁，等待获取<0x052e39d8>这个锁

　　　　Thread1获取了<0x052e39d8>的锁，等待获取<0x052e39e0>这个锁

　　　　由此可见，发生了死锁；