Shulou(Shulou.com)06/01 Report--

How to carry out the keepAliveTime=0 description of ThreadPoolExecutor, in view of this problem, this article introduces the corresponding analysis and answer in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible method.

Explain the keepAliveTime=0 of ThreadPoolExecutor.

The above picture is from the Art of concurrent programming, which has the following description:

"

"when the number of threads in the thread pool is greater than corePoolSize, keepAliveTime is the maximum amount of time for redundant idle threads to wait for a new task, after which extra threads will be terminated. Setting keepAliveTime to 0L here means that the extra idle threads will be terminated immediately."

A lot of information on the Internet says that 0 means that the thread survives permanently when it is idle. In fact, it is not accurate.

Attach the verification code:

Public static void main (String [] args) throws InterruptedException {

/ / A thread pool has been created

ThreadPoolExecutor executor = new ThreadPoolExecutor (1

two,

0, TimeUnit.SECONDS

New LinkedBlockingQueue (1))

For (int I = 0; I

< 3; i++) { executor.execute(new DemoTask(i)); } while (true) { System.out.println("总线程数：" + executor.getPoolSize() + ", 当前活跃线程数：" + executor.getActiveCount()); TimeUnit.SECONDS.sleep(1); } } static class DemoTask implements Runnable { int num; public DemoTask(int i) { this.num = i; } @Override public void run() { System.out.println("num=" + num + " Thread = " + Thread.currentThread().getName()); if (num >

= 1) {

Try {

TimeUnit.SECONDS.sleep (1)

System.out.println ("num=" + num + "sleep 1 s end")

} catch (InterruptedException e) {

E.printStackTrace ()

}

} else {

Try {

TimeUnit.SECONDS.sleep (3)

System.out.println ("num=" + num + "sleep 3s end")

} catch (InterruptedException e) {

E.printStackTrace ()

}

}

}

}

Print the results:

Num=2 Thread = pool-1-thread-2

Number of bus programs: 2, current number of active threads: 2

Num=0 Thread = pool-1-thread-1

End of num=2 sleep 1 s

Num=1 Thread = pool-1-thread-2

Number of bus programs: 2, current number of active threads: 2

End of num=1 sleep 1 s

Number of bus programs: 1, current number of active threads: 1

End of num=0 sleep 3 s

Number of bus programs: 1, current number of active threads: 1

Number of bus programs: 1, current number of active threads: 0

Number of bus programs: 1, current number of active threads: 0

This is the answer to the keepAliveTime=0 explanation question on how to carry out ThreadPoolExecutor. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel to learn more about it.

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