我有一个多线程的应用程序.当使用Thread.start()手动启动线程时,每个并发线程使用恰好25％的cpu(或者恰好一个核心 – 这是在四核机器上).因此,如果我运行两个线程,cpu使用率恰好是50％.

然而,当使用ExecutorService运行线程时,似乎有一个“鬼”线程消耗cpu资源！ One Thread使用50％而不是25％,两个线程使用75％等.

这可能是某种Windows任务管理器的人工制品吗？

Excutor服务代码是

ExecutorService executor = Executors.newFixedThreadPool(threadAmount);

for (int i = 1; i < 50; i++) {
    Runnable worker = new ActualThread(i);
    executor.execute(worker);
}
executor.shutdown();
while (!executor.isTerminated()) {

}
System.out.println("Finished all threads");

和Thread.start()代码是：

ActualThread one= new ActualThread(2,3);
ActualThread two= new ActualThread(3,4);
...

Thread threadOne = new Thread(one);
Thread threadTtwo = new Thread(two);
...

threadOne.start();
threadTwo.start();
...

while (!executor.isTerminated()) {

}

final ExecutorService executor = Executors.newFixedThreadPool(threadAmount);
final List<Callable<Object>> tasks = new ArrayList<Callable<Object>>();

for (int i = 1; i < 50; i++) {
    tasks.add(Executors.callable(new ActualThread(i)));
}
executor.invokeAll(tasks);
executor.shutdown();  // not really necessary if the executor goes out of scope.
System.out.println("Finished all threads");