JVM jstack实战之死锁问题详解

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 拿到了 obj1 的锁！");

                try {
                    // 停顿2秒的意义在于，让Thread2线程拿到obj2的锁
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                synchronized (obj2){
                    System.out.println("Thread1 拿到了 obj2 的锁！");
                }
            }
        }
    }

    private static class Thread2 implements Runnable{
        @Override
        public void run() {
            synchronized (obj2){
                System.out.println("Thread2 拿到了 obj2 的锁！");

                try {
                    // 停顿2秒的意义在于，让Thread1线程拿到obj1的锁
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                synchronized (obj1){
                    System.out.println("Thread2 拿到了 obj1 的锁！");
                }
            }
        }
    }

}

C:\Users\dell> jstack 17196
2021-07-25 21:52:25
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.171-b11 mixed mode):

"DestroyJavaVM" #14 prio=5 os_prio=0 tid=0x00000000029f2800 nid=0x1868 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Thread-1" #13 prio=5 os_prio=0 tid=0x000000001e5d3000 nid=0x6994 waiting for monitor entry [0x000000001f49f000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at cn.zjq.jvm.TestDeadLock$Thread2.run(TestDeadLock.java:49)
        - waiting to lock <0x000000076b688680> (a java.lang.Object)
        - locked <0x000000076b688690> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:748)

"Thread-0" #12 prio=5 os_prio=0 tid=0x000000001e5d2000 nid=0x21d8 waiting for monitor entry [0x000000001f39f000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at cn.zjq.jvm.TestDeadLock$Thread1.run(TestDeadLock.java:29)
        - waiting to lock <0x000000076b688690> (a java.lang.Object)
        - locked <0x000000076b688680> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:748)

"Service Thread" #11 daemon prio=9 os_prio=0 tid=0x000000001e5aa800 nid=0x6e40 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread3" #10 daemon prio=9 os_prio=2 tid=0x000000001e516000 nid=0x1828 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread2" #9 daemon prio=9 os_prio=2 tid=0x000000001e505000 nid=0x712c waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread1" #8 daemon prio=9 os_prio=2 tid=0x000000001e501000 nid=0x7f5c waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #7 daemon prio=9 os_prio=2 tid=0x000000001e4ed000 nid=0x2dc0 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Monitor Ctrl-Break" #6 daemon prio=5 os_prio=0 tid=0x000000001e4ff800 nid=0x5040 runnable [0x000000001ec9e000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
        at java.net.SocketInputStream.read(SocketInputStream.java:171)
        at java.net.SocketInputStream.read(SocketInputStream.java:141)
        at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
        at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
        at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
        - locked <0x000000076b7d0200> (a java.io.InputStreamReader)
        at java.io.InputStreamReader.read(InputStreamReader.java:184)
        at java.io.BufferedReader.fill(BufferedReader.java:161)
        at java.io.BufferedReader.readLine(BufferedReader.java:324)
        - locked <0x000000076b7d0200> (a java.io.InputStreamReader)
        at java.io.BufferedReader.readLine(BufferedReader.java:389)
        at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:64)

"Attach Listener" #5 daemon prio=5 os_prio=2 tid=0x000000001e45b800 nid=0x49d8 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=2 tid=0x000000001e445800 nid=0x6b90 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=1 tid=0x000000001e441800 nid=0x2c0c in Object.wait() [0x000000001e91e000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x000000076b508ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
        - locked <0x000000076b508ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:212)

"Reference Handler" #2 daemon prio=10 os_prio=2 tid=0x000000001c54d000 nid=0x6508 in Object.wait() [0x000000001e41f000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x000000076b506bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
        - locked <0x000000076b506bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"VM Thread" os_prio=2 tid=0x000000001c549000 nid=0x5af4 runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x0000000002a08800 nid=0x347c runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x0000000002a0a000 nid=0x6bc8 runnable

"GC task thread#2 (ParallelGC)" os_prio=0 tid=0x0000000002a0b800 nid=0x7d20 runnable

"GC task thread#3 (ParallelGC)" os_prio=0 tid=0x0000000002a0d000 nid=0x728c runnable

"GC task thread#4 (ParallelGC)" os_prio=0 tid=0x0000000002a0f800 nid=0x595c runnable

"GC task thread#5 (ParallelGC)" os_prio=0 tid=0x0000000002a10800 nid=0x43fc runnable

"GC task thread#6 (ParallelGC)" os_prio=0 tid=0x0000000002a14800 nid=0x3c50 runnable

"GC task thread#7 (ParallelGC)" os_prio=0 tid=0x0000000002a16000 nid=0x364c runnable

"VM Periodic Task Thread" os_prio=2 tid=0x000000001e5ca000 nid=0x1da4 waiting on condition

JNI global references: 12


Found one Java-level deadlock:
=============================
"Thread-1":
  waiting to lock monitor 0x000000001c5535f8 (object 0x000000076b688680, a java.lang.Object),
  which is held by "Thread-0"
"Thread-0":
  waiting to lock monitor 0x000000001c550d68 (object 0x000000076b688690, a java.lang.Object),
  which is held by "Thread-1"

Java stack information for the threads listed above:
===================================================
"Thread-1":
        at cn.zjq.jvm.TestDeadLock$Thread2.run(TestDeadLock.java:49)
        - waiting to lock <0x000000076b688680> (a java.lang.Object)
        - locked <0x000000076b688690> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:748)
"Thread-0":
        at cn.zjq.jvm.TestDeadLock$Thread1.run(TestDeadLock.java:29)
        - waiting to lock <0x000000076b688690> (a java.lang.Object)
        - locked <0x000000076b688680> (a java.lang.Object)
        at java.lang.Thread.run(Thread.java:748)

Found 1 deadlock.