java并发编程（9）：死锁（含代码）-编程开发技术

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1、hva并发编程(9)：死锁(含代码)-编程开发技术Java并发编程(9)：死锁(含代码)原文出处：兰亭风雨当线程需要同时持冇多个锁时，冇可能产生死锁。考虑如下情形：线程A当前持有互斥所锁lockl,线程B当前持有互斥锁lock2o接下来，当线程A仍然持有lockl时，它试图获取lock2,因为线程B正持有lock2,因此线程A会阻塞等待线程B对lock2的释放。如果此时线程B在持有lock2的时候,也在试图获取lockl,因为线程A正持有lockl,因此线程B会阻塞等待A对］ockl的释放。二者都在等待对方所持有锁的释放，而二者却又都没释放自己所持有的锁，这时二者

2、便会一直阻塞下去。这种情形称为死锁。下而给出一个两个线程间产生死锁的示例，如下：publicclassDeadlockextendsObject{privateStringobjID;publicDeadlock(Stringid){objlD=id;}publicsynchronizedvoidcheckOther(Deadlockother){print(''enteringcheckOthcr()，z);try{Thread,sleep(2000);}catch(InterruptedExceptionx){}print(“incheckOther()-ab

3、outto"+"invokeother,action()'〃)；//调用other对彖的action方法，由于该方法是同步方法,因此会试图获取other对彖的对彖锁other,action();print(z，leavingcheckOther()z，);}publicsynchronizedvoidaction(){print(〃enteringaction()z，);try{Thread,sleep(500);}catch(InterruptedExceptionx){}print(''leavingaction()，z);publicvoidprint(St

4、ringmsg){threadPrint(/，objID=z，+objID+〃一〃+msg);publicstaticvoidthreadPrint(Stringmsg){StringthreadName=Thread.currentThread().getNameO;System,out.println(threadName+〃：〃+msg);}publicstaticvoidmain(String[]args){finalDeadlockobjl=newDeadlock(〃obj1〃)；finalDeadlockobj2=newDeadlock(〃obj2〃)

5、；RunnablerunA二newRunnable(){publicvoidrun(){objl.chcckOthcr(obj2);}};ThreadthreadA=newThread(runA,，zthreadA，z);thrcadA.start();try{Thread,sleep(200);}catch(InterruptedExceptionx){}RunnablerunB二newRunnable(){publicvoidrun(){obj2.checkOther(objl);}};ThreadthreadB=newThread(runB,z/thread

6、B/，);threadB.start();try{Thread,sleep(5000);}catch(IntcrruptcdExccptionx){}threadPrint(''finishedsleeping");threadPrint("abouttointerrupt()threadA");thrcadA.intcrrupt();try{Thread,sleep(1000);}catch(InterruptedExceptionx){}threadPrint(/zabouttointerrupt()threadBz/);threadB・interrupt()

7、;try{Thread,sleep(1000);}catch(InterruptedExceptionx){}threadPrint(/zdidthatbreakthedeadlock?");}运行结果如下:notfindthemainclass:定C：.IIVD0YSsysteB32cad.exe一javaDeadlockDeadlocks.Programwillexit.E：>javabreadA:tehreadB：DeadlockobjID=objlobjID=obj2巳ntering巳nteringcheckOtherOcheckOtherOoth

8、er.ac