java - 如何更改 ScheduledExecutorService 中的线程池大小？

Question

我需要带有动态线程池的 ScheduledExecutorService 。我想动态更改线程池大小。我怎样才能做到这一点？

class ExecutorTask {
    private ScheduledExecutorService service;

    public void add(Task task) {
        // I need thread pool size == count added tasks.
        service.scheduleAtFixedRate(this::start, 0, 10, TimeUnit.SECONDS);
    }
}

也许你可以建议我另一个线程池？

Answer 1

您可以使用ScheduledThreadPoolExecutor轻松做到这一点.

    //Init executor
    int initialPoolSize = 5;
    ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(initialPoolSize);

    //[...] do something

    //Change max size
    int newPoolSize = 10;
    executor.setCorePoolSize(newPoolSize);

注意继承的方法setMaximumPoolSize(int)有no effect on ScheduledThreadPoolExecutor 。要更改池大小，您需要更改 corePoolSize:

While this class inherits from ThreadPoolExecutor, a few of the inherited tuning methods are not useful for it. In particular, because it acts as a fixed-sized pool using corePoolSize threads and an unbounded queue, adjustments to maximumPoolSize have no useful effect. Additionally, it is almost never a good idea to set corePoolSize to zero or use allowCoreThreadTimeOut because this may leave the pool without threads to handle tasks once they become eligible to run.