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)