线程池 schedule 2
Topic source
a) 在FixedRate模式下，假设每秒触发，如果某次任务执行时间超过1秒，后续任务会不会并发执行？
i. Schedule任务超时结束，则后续任务立即执行以持续补时差，直到回归正常(时间->任务)一一对应的序列
b) 如果任务抛出了异常，后续任务是否继续执行？
i. 任务抛出了异常，如果通过catch获取，则处理后继续执行；否则，线程将被迫停止并由RUNNABLE状态进入 WAITING 状态。
ii. 任务抛出了错误，线程也将被迫停止
- 1
Junes_99994
import java.util.concurrent.*;
import java.util.*;
import java.text.SimpleDateFormat;
import java.util.Set;
public class Main {
public static void main(String[] args) {
// 创建一个固定大小的线程池:
// ScheduledExecutorService pool = Executors.newScheduledThreadPool(4);
ScheduledThreadPoolExecutor pool = new ScheduledThreadPoolExecutor(4);
ScheduledFuture<?> future = pool.scheduleAtFixedRate(new MyTask(), 0,
200, TimeUnit.MILLISECONDS);
// System.out.println((pool.getQueue().element()));
// System.out.println(Thread..getState() Runnable.);
try {
// pool.shutdown(); // Disable new tasks from being submitted
if (!pool.awaitTermination(2, TimeUnit.SECONDS)) {
cprint("time Delayed:" + -future.getDelay(TimeUnit.MILLISECONDS) + "ms");
// https://www.educative.io/answers/what-is-the-futureisdone-method-in-java
cprint("task state:" + future.isDone());
Set<Thread> threadSet = Thread.getAllStackTraces().keySet();
// threadset
for (Thread t : threadSet) {
// Printing the thread status using getState()
if (t.getName().substring(0, 4).equals("pool")) {
cprint("Thread :" + t + ":"
+ "Thread status : "
+ t.getState());
}
try {
Thread.sleep(20);
} catch (InterruptedException e) {
cprint(e.toString());
}
}
pool.shutdownNow();//
// pool.shutdown();// Wait a while for existing tasks to terminate
// Wait a while for tasks to respond to being cancelled
if (!pool.awaitTermination(2, TimeUnit.SECONDS)) {
cprint("Pool did not terminate");
}
}
} catch (InterruptedException ie) {
// (Re-)Cancel if current thread also interrupted
pool.shutdownNow();
// Preserve interrupt status
Thread.currentThread().interrupt();
}
}
private static void cprint(String s) {
final String ANSI_RESET = "\u001B[0m";
final String ANSI_RED = "\u001B[31m";
final String ANSI_GREEN = "\u001B[32m";
System.out.println(ANSI_GREEN + s + ANSI_RESET);
}
}
class MyTask implements Runnable {
static final SimpleDateFormat sdfDate = new SimpleDateFormat("HH:mm:ss.SSS");
Date st = new Date();
Date et = new Date();
@Override
public void run() {
// System.out.println(Thread.currentThread().getState());
String threadId = Thread.currentThread().getName();
Date dt = new Date();
System.out.println("interval:" + (dt.getTime() - st.getTime()) + "ms");
st = new Date(dt.getTime());
System.out.println(sdfDate.format(st) + ":" + "start task " + threadId);
try {
int delta = 100 + (int) (Math.random() * 200);
Thread.sleep(delta);
et = new Date();
System.out.println(sdfDate.format(et) + ":" + "end task " + threadId);
System.out.println("period:" + (et.getTime() - st.getTime()) + "ms\n");
// if (delta > 250) {//exception
// int x = 0;
// System.out.println(5 / x);
// }
// if (delta > 200) {// error
// m();
// }
} catch (InterruptedException e) {
System.out.println(e.toString());
}
// catch (Exception e) {
// System.out.println(e.toString());
// }
}
private void m() {
try {
m();
} catch (Exception e) {
System.out.println(e.toString());
}
};
}