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fix thread logic #168

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fix thread logic #168

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43 changes: 23 additions & 20 deletions docs/basics/concurrent-coding/volatile.md
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Original file line number Diff line number Diff line change
Expand Up @@ -82,27 +82,30 @@ volatile可以禁止指令重排，这就保证了代码的程序会严格按照

public class Test {
public volatile int inc = 0;
public void increase() {
inc++;
}
public static void main(String[] args) {
final Test test = new Test();
for(int i=0;i<10;i++){
new Thread(){
public void run() {
for(int j=0;j<1000;j++)
test.increase();
};
}.start();
}

while(Thread.activeCount()>1) //保证前面的线程都执行完
Thread.yield();
System.out.println(test.inc);

public void increase() {
inc++;
}

public static void main(String[] args) throws InterruptedException {
final Test test = new Test();
for(int i=0;i<10;i++){
Thread threads[]=new Thread[10];
threads[i]=new Thread(){
@Override
public void run() {
for (int j = 0; j < 1000; j++) {
test.increase();
}
}
};
threads[i].join();
threads[i].start();
}

System.out.println(test.inc);
}
}


以上代码比较简单，就是创建10个线程，然后分别执行1000次`i++`操作。正常情况下，程序的输出结果应该是10000，但是，多次执行的结果都小于10000。这其实就是`volatile`无法满足原子性的原因。
Expand Down Expand Up @@ -135,4 +138,4 @@ volatile可以禁止指令重排，这就保证了代码的程序会严格按照

[1]: http://47.103.216.138/archives/2550
[2]: http://47.103.216.138/archives/2637
[3]: http://47.103.216.138/archives/2618
[3]: http://47.103.216.138/archives/2618