Java中工具Jstack的使用实例

jstack [ options ] pid
jstack [ options ] executable core
jstack [ options ] [ server-id@ ] remote-hostname-or-IP
OPTIONS
       -F
              Force a stack dump when jstack [-l] pid does not respond.
       -l
              Long listing. Prints additional information about locks such as a list of owned java.util.concurrent ownable synchronizers. See the
              AbstractOwnableSynchronizer class description at
              http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/locks/AbstractOwnableSynchronizer.html
       -m
              Prints a mixed mode stack trace that has both Java and native C/C++ frames.

public class Jstack {
    private static Object obj1 = new Object();
    private static Object obj2 = new Object();
    public static void main(String[] args) {
        new Thread(() -> {
            synchronized (obj1) {
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                synchronized (obj2) {
                }
            }
        }).start();
        new Thread(() -> {
            synchronized (obj2) {
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                synchronized (obj1) {
                }
            }
        }).start();
    }
}

"Thread-1" #12 prio=5 os_prio=0 tid=0x00007fdff871c800 nid=0x3cc2 waiting for monitor entry [0x00007fdfce0fc000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at com.example.demo.jstack.Jstack.lambda$main$1(Jstack.java:36)
	- waiting to lock <0x000000076e925a90> (a java.lang.Object)
	- locked <0x000000076e925aa0> (a java.lang.Object)
	at com.example.demo.jstack.Jstack$$Lambda$2/2052001577.run(Unknown Source)
	at java.lang.Thread.run(Thread.java:748)

"Thread-0" #11 prio=5 os_prio=0 tid=0x00007fdff871a800 nid=0x3cc1 waiting for monitor entry [0x00007fdfce1fc000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at com.example.demo.jstack.Jstack.lambda$main$0(Jstack.java:25)
	- waiting to lock <0x000000076e925aa0> (a java.lang.Object)
	- locked <0x000000076e925a90> (a java.lang.Object)
	at com.example.demo.jstack.Jstack$$Lambda$1/1174361318.run(Unknown Source)
	at java.lang.Thread.run(Thread.java:748)

Found one Java-level deadlock:
=============================
"Thread-1":
  waiting to lock monitor 0x00007fdfac006638 (object 0x000000076e925a90, a java.lang.Object),
  which is held by "Thread-0"
"Thread-0":
  waiting to lock monitor 0x00007fdfac003da8 (object 0x000000076e925aa0, a java.lang.Object),
  which is held by "Thread-1"

Java stack information for the threads listed above:
===================================================
"Thread-1":
	at com.example.demo.jstack.Jstack.lambda$main$1(Jstack.java:36)
	- waiting to lock <0x000000076e925a90> (a java.lang.Object)
	- locked <0x000000076e925aa0> (a java.lang.Object)
	at com.example.demo.jstack.Jstack$$Lambda$2/2052001577.run(Unknown Source)
	at java.lang.Thread.run(Thread.java:748)
"Thread-0":
	at com.example.demo.jstack.Jstack.lambda$main$0(Jstack.java:25)
	- waiting to lock <0x000000076e925aa0> (a java.lang.Object)
	- locked <0x000000076e925a90> (a java.lang.Object)
	at com.example.demo.jstack.Jstack$$Lambda$1/1174361318.run(Unknown Source)
	at java.lang.Thread.run(Thread.java:748)
Found 1 deadlock.

public class JstackDemo {
    public static Executor executor = Executors.newFixedThreadPool(3);
    private static Object lock = new Object();
    public static void main(String[] args) {
        Task task1 = new Task();
        Task task2 = new Task();
        executor.execute(task1);
        executor.execute(task2);
    }

    public static class Task implements Runnable {
        @Override
        public void run() {
            synchronized (lock) {
                run0();
            }
        }

        private void run0() {
            int i = 0;
            while (true) {
                i++;
            }
        }
    }
}