Java 如何同时启动两个线程

Z时代
2024-01-10
分类：问答

程应在同一瞬间开始。我了解，如果你这样做thread1.start()，则下次执行之前需要花费几毫秒的时间thread2.start()。

可能还是不可能？线程应该在同一瞬间开始。我知道，如果你执行thread1.start（），则下次执行thread2.start（）需要几毫秒。

这是可能的还是不可能的？

回答：

要完全同时（至少尽可能好）启动线程，可以使用CyclicBarrier：

// We want to start just 2 threads at the same time, but let's control that 
// timing from the main thread. That's why we have 3 "parties" instead of 2.
final CyclicBarrier gate = new CyclicBarrier(3);
Thread t1 = new Thread(){
    public void run(){
        gate.await();
        //do stuff    
    }};
Thread t2 = new Thread(){
    public void run(){
        gate.await();
        //do stuff    
    }};
t1.start();
t2.start();
// At this point, t1 and t2 are blocking on the gate. 
// Since we gave "3" as the argument, gate is not opened yet.
// Now if we block on the gate from the main thread, it will open
// and all threads will start to do stuff!
gate.await();
System.out.println("all threads started");