Java中常见死锁与活锁的实例详解

public class Test {
  Object leftLock = new Object();
  Object rightLock = new Object();
  public static void main(String[] args) {
    final Test test = new Test();
    Thread a = new Thread(new Runnable() {
      @Override      public void run() {
        int i=0;
        while (i<10)
        {
          test.leftRight();
          i++;
        }
      }
    },"aThread");
    Thread b = new Thread(new Runnable() {
      @Override      public void run() {
        int i=0;
        while (i<10)
        {
          test.rightleft();
          i++;
        }
      }
    },"bThread");
    a.start();
    b.start();
  }

  public void leftRight(){
    synchronized (leftLock){
      System.out.println(Thread.currentThread().getName()+":leftRight:get left");
      synchronized (rightLock){
        System.out.println(Thread.currentThread().getName()+":leftRight:get right");
      }
    }
  }

  public void rightleft(){
    synchronized (rightLock){
      System.out.println(Thread.currentThread().getName()+":rightleft: get right");
      synchronized (leftLock){
        System.out.println(Thread.currentThread().getName()+":rightleft: get left");
      }
    }
  }

}

"bThread" prio=5 tid=0x00007fabb2001000 nid=0x5503 waiting for monitor entry [0x000000011d54b000]
  java.lang.Thread.State: BLOCKED (on object monitor)
  at main.lockTest.Test.rightleft(Test.java:52)
  - waiting to lock <0x00000007aaee5748> (a java.lang.Object)
  - locked <0x00000007aaee5758> (a java.lang.Object)
  at main.lockTest.Test$2.run(Test.java:30)
  at java.lang.Thread.run(Thread.java:745)

  Locked ownable synchronizers:
  - None

"aThread" prio=5 tid=0x00007fabb2801000 nid=0x5303 waiting for monitor entry [0x000000011d448000]
  java.lang.Thread.State: BLOCKED (on object monitor)
  at main.lockTest.Test.leftRight(Test.java:43)
  - waiting to lock <0x00000007aaee5758> (a java.lang.Object)
  - locked <0x00000007aaee5748> (a java.lang.Object)
  at main.lockTest.Test$1.run(Test.java:19)
  at java.lang.Thread.run(Thread.java:745)

  Locked ownable synchronizers:
  - None

public class ExecutorLock {
  private static ExecutorService single=Executors.newSingleThreadExecutor();
  public static class AnotherCallable implements Callable<String>{

    @Override    public String call() throws Exception {
      System.out.println("in AnotherCallable");
      return "annother success";
    }
  }


  public static class MyCallable implements Callable<String>{

    @Override    public String call() throws Exception {
      System.out.println("in MyCallable");
      Future<String> submit = single.submit(new AnotherCallable());
      return "success:"+submit.get();
    }
  }
  public static void main(String[] args) throws ExecutionException, InterruptedException {
    MyCallable task = new MyCallable();
    Future<String> submit = single.submit(task);
    System.out.println(submit.get());
    System.out.println("over");
    single.shutdown();
  }
}

in MyCallable

"main" prio=5 tid=0x00007fab3f000000 nid=0x1303 waiting on condition [0x0000000107d63000]
  java.lang.Thread.State: WAITING (parking)
  at sun.misc.Unsafe.park(Native Method)
  - parking to wait for <0x00000007aaeed1d8> (a java.util.concurrent.FutureTask)
  at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
  at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:425)
  at java.util.concurrent.FutureTask.get(FutureTask.java:187)
  at main.lockTest.ExecutorLock.main(ExecutorLock.java:32)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:606)
  at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)

  Locked ownable synchronizers:
  - None
..
"pool-1-thread-1" prio=5 tid=0x00007fab3f835800 nid=0x5303 waiting on condition [0x00000001199ee000]
  java.lang.Thread.State: WAITING (parking)
  at sun.misc.Unsafe.park(Native Method)
  - parking to wait for <0x00000007ab0f8698> (a java.util.concurrent.FutureTask)
  at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
  at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:425)
  at java.util.concurrent.FutureTask.get(FutureTask.java:187)
  at main.lockTest.ExecutorLock$MyCallable.call(ExecutorLock.java:26)
  at main.lockTest.ExecutorLock$MyCallable.call(ExecutorLock.java:20)
  at java.util.concurrent.FutureTask.run(FutureTask.java:262)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
  at java.lang.Thread.run(Thread.java:745)

  Locked ownable synchronizers:
  - <0x00000007aaeed258> (a java.util.concurrent.ThreadPoolExecutor$Worker)