Executor usage

最新推荐文章于 2021-01-18 22:42:01 发布

最新推荐文章于 2021-01-18 22:42:01 发布 · 95 阅读

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本文介绍了如何使用Java中的ExecutorService来管理线程池，包括创建不同类型的线程池、提交任务及停止线程的方法。通过示例代码展示了固定大小线程池的使用，并解释了ExecutorService相较于Executor提供的额外功能。

Executor is used to arrange thread execution. Basicly speaking, just manage, how many threads are permited to run together.

ExecutorService obj = Executors.newSingleThreadExecutor( ) -- only 1

ExecutorService obj = Executors.newFixedThreadPool(int poolSize) -- fix amount

ExecutorService obj = Executors.newCachedThreadPool( ) --- as many as it can

Code Sample

Executor e = Executors.newFixedThreadPool(5);

e.execute(new RunnableTask1( ));

e.execute(new RunnableTask2( ));

e.execute(new RunnableTask3( ));

While in another aritcle, you can see that, Executors.newFixedThreadPool(5) returns a ExecutorService. Actually, ExecutorService is a subclass of Executor, and it supplies more functionalities than Executor.

As far as ExecutorService is concerned, it supplies only one advanced function than Executor---how to stop the threads.

service.shutdownNow(); //Try to finish all Runnables(started and not started(in queue)), then, stop Executor.

service.shutdown(); //Directly stop the Executor, terminate running Runables, return back not started, yet in queue Runables.

There is a internal Queue maintained by ExecutorService. That's the core idea.

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Another point, Please pay attention to how they are used to different targets.

//FutureObject = ExecutorService.submit(Callable object);

//Executor.execut(Runnable object); //without any returns.

Future<BigInteger> prime1 = service.submit(new RandomPrimeSearch(512));

Future<BigInteger> prime2 = service.submit(new RandomPrimeSearch(512));

Future<BigInteger> prime3 = service.submit(new RandomPrimeSearch(512));