问题描述
当我们使用Java的Executor服务创建线程池并将线程提交到该线程池时，这些线程的执行顺序是什么?
As we create a Thread pool using Java's Executor service and submit threads to this thread pool, what is the order in which those threads get executed?
我想确保线程先提交，然后先执行.例如，在下面的代码中，我希望先执行前5个线程，然后再执行下5个线程，依此类推...
I want to ensure that threads submitted first, execute first.For example, in the code below, I want first 5 threads to get executed first, followed by the next 5 threads and so on...
// Create a thread pool of 5 threads.
ScheduledExecutorService exService = Executors.newScheduledThreadPool(5, new ModifiedThreadFactory("ReadThreadPool"));
// Create 100 threads.
MyThread[] threads = createMyThreads(100);
// Submit these 100 threads to thread pool for execution.
for(MyThread thread : threads) {
exService.submit(thread);
}
Java的线程池是否为此目的提供了任何API，还是我们需要在最后实现一个FIFO队列来实现此目的?如果Java的线程池不提供任何此类功能，我真的很想了解不存在该功能背后的原因，因为这对我来说似乎是一个非常常见的用例.从技术上讲是不可能的(我认为这不太可能)，还是只是错过了?
Does Java's Thread Pool provide any API for this purpose, or do we need to implement a FIFO queue at our end to achieve this.If Java's thread pool does not provide any such functionality, I am really interested to understand the reason behind the non-existence of this functionality as it appears like a very common use-case to me.Is it technically not possible (which I think is quite unlikely), or is it just a miss?
推荐答案
这是默认行为. ScheduledThreadExecutor(尽管未安排任何时间，但仍在使用)从ThreadPoolExecutor扩展而来.提交给ThreadPoolExecutor的任务存储在BlockingQueue中，直到有一个线程可以使用并执行它们.队列是FIFO.
That's the default behavior. ScheduledThreadExecutor (that you're using although you're not scheduling anything) extends from ThreadPoolExecutor. Tasks submitted to a ThreadPoolExecutor are stored in a BlockingQueue until one thread is available to take them and execute them. And queues are FIFO.
有关详细说明，请参见 javadoc .
This is decscribed in details in the javadoc.
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