在Groovy中加入主题 [英] Joining Thread in Groovy

问题描述

加入方法是做什么的？

如：

What does the join method do?
As in:

def thread = Thread.start { println "new thread" }
thread.join()

即使没有 join 语句，这段代码也可以正常工作。

This code works fine even without the join statement.

推荐答案

与Java中的相同 - 它会导致 连接的线程阻塞，直到线程被调用的 join 对象已终止。

The same as it does in Java - it causes the thread that called join to block until the thread represented by the Thread object on which join was called has terminated.

您可以在产生新线程后让主线程执行其他操作（例如， println ），以查看区别。

You can see the difference if you make the main thread do something else (e.g. a println) after spawning the new thread.

def thread = Thread.start {
  sleep(2000)
  println "new thread"
}
//thread.join()
println "old thread"

没有加入这个println会在另一个线程仍在运行时发生，所以你会得到 old thread ，两秒后由新线程。使用 join 时，主线程必须等到其他线程完成后，才能在两秒内得到任何内容，然后 new thread ，然后旧线程。

Without the join this println can happen while the other thread is still running, so you'll get old thread, followed two seconds later by new thread. With the join the main thread must wait until the other thread has finished, so you'll get nothing for two seconds, then new thread, then old thread.

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