Java Multithread立即停止所有其他线程

Question

我有以下代码：

public class BruteForceThread implements Callable<String> {

private static volatile boolean stopped = false;        

public String call() {

    String password = this.getNextPassword();

    while (!stopped) {

        System.out.println(numberOfThreat + ": " + password);

        synchronized(this) {
            try {
                if (this.testPassword(password)) {
                    stopped = true;
                    return password;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        password = this.getNextPassword();

    }
    return "";

}
}

主班：

public static void main(String[] args) throws IOException {

int numberOfThreads = 2;
ExecutorService executor = Executors.newFixedThreadPool(numberOfThreads);
CompletionService<String> pool = new ExecutorCompletionService<String>(executor);
for (int i = 1; i < numberOfThreads + 1; i++) {
  Callable<String> bruteForce = new BruteForceThread(...);
  pool.submit(bruteForce);
}

executor.shutdown();

    for(int i = 0; i < numberOfThreads; i++){
        try {
            String result = pool.take().get();
            if (result != "") {
                System.out.println("Your password: " + result);
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }

executor = null;
}

输出：...

1: aa <- here first thread found a password
2: Fa <- second thread is continue
2: Fb
2: Fc
... many more ...
2: IZ
Your password: aa

如果一个线程找到密码并将其设置为true，则另一个线程不会立即停止。 为什么？

Answer 1

将有等待写入控制台的线程。 这意味着某些线程或所有线程都可能在检查停止状态和输出到屏幕之间。

顺便说一句，除非您以高等待时间入侵网站，否则您可能会发现破解密码仅使用与CPU数量相同的线程来完成。 更多线程可能会增加开销并减慢它的速度。