쓰레드 동작의 완료를 확인한다는 것은 다음 2가지를 말한다.
- 일반 쓰레드에서 쓰레드가 살아있는지 확인하기
- Executor에서 태스크가 종료되었는지 확인하기
사실 일반 쓰레드에서도 쓰레드가 살아있는지를 확인하는 것보다 태스크의 종료에 대해 관심이 더 많지만 쓰레드 API 수준에서는 제공하지 않는다.
1. 일반 쓰레드에서 쓰레드가 살아있는지 확인하기
일반 스레드에서 쓰레드가 살이있는지 확인하는 방법은 Thread.isAlive() 메소드를 사용하는 것이다. 예제로 확인하자.
import java.util.concurrent.TimeUnit;
public class ThreadAliveCheck {
public static void main(String argc[]) throws InterruptedException {
String currentThreadName = Thread.currentThread().getName();
System.out.println("["+ currentThreadName + "]" + " thread starts here...");
Thread thread = new Thread(new MyRunnableTask(10), "Thread-1");
boolean threadIsAlive = thread.isAlive();
System.out.println("thread Aliveness before start: " + threadIsAlive);
thread.start();
for(int i = 0; i< 4; i++) {
TimeUnit.MILLISECONDS.sleep(20);
System.out.println("thread Aliveness : " + thread.isAlive());
}
System.out.println("["+ currentThreadName + "]" + " thread ends here...");
}
}
class MyRunnableTask implements Runnable {
private static int count = 0;
private int id;
private String taskId;
private long sleepTime;
@Override
public void run() {
String currentThreadName = Thread.currentThread().getName();
System.out.println("#### <" + currentThreadName +"," + taskId + "> starting...####");
for(int i = 0; i<4; i++) {
System.out.println("<" + currentThreadName + "," + taskId + "> TICK TICK" + i);
try {
TimeUnit.MILLISECONDS.sleep(sleepTime);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("#### <" + currentThreadName + "," + taskId + "> done...####");
}
public MyRunnableTask(long sleepTime) {
this.id = ++count;
this.taskId = "MyRunnableTask" + id;
this.sleepTime = sleepTime;
}
}
아래 결과와 같이 쓰레드가 동작하고 있는동안에만 isAlive()가 true를 반환함을 알 수 있다.
[main] thread starts here...
thread Aliveness before start: false
#### <Thread-1,MyRunnableTask1> starting...####
<Thread-1,MyRunnableTask1> TICK TICK0
<Thread-1,MyRunnableTask1> TICK TICK1
thread Aliveness : true
<Thread-1,MyRunnableTask1> TICK TICK2
<Thread-1,MyRunnableTask1> TICK TICK3
thread Aliveness : true
#### <Thread-1,MyRunnableTask1> done...####
thread Aliveness : false
thread Aliveness : false
[main] thread ends here...
2. Executor에서 태스크가 종료되었는지 확인하기
태스크의 종료는 반드시 태스크가 정상적으로 종료함만을 의미하지 않는다. Exception으로 종료되는 것도 포함해서 종료되었는지 확인하는 것은 Future.isDone()함수이다.
예제는 다음과 같다.
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
public class ExecutorTaskCompleteCheck {
public static void main(String argc[]) throws InterruptedException {
String currentThreadName = Thread.currentThread().getName();
System.out.println("["+ currentThreadName + "]" + " thread starts here...");
ExecutorService execService = Executors.newCachedThreadPool( new NamedThreadsFactory());
Future<?> future = execService.submit(new MyRunnableTask(10));
execService.shutdown();
for(int i = 0; i< 4; i++) {
TimeUnit.MILLISECONDS.sleep(20);
System.out.println("Task completion : " + future.isDone());
}
System.out.println("["+ currentThreadName + "]" + " thread ends here...");
}
}
class NamedThreadsFactory implements ThreadFactory {
private static int count = 0;
private static String Name = "MyThread-";
@Override
public Thread newThread(Runnable r) {
return new Thread(r, Name + ++count);
}
}
class MyRunnableTask implements Runnable {
private static int count = 0;
private int id;
private String taskId;
private long sleepTime;
@Override
public void run() {
String currentThreadName = Thread.currentThread().getName();
System.out.println("#### <" + currentThreadName +"," + taskId + "> starting...####");
for(int i = 0; i<4; i++) {
System.out.println("<" + currentThreadName +"," + taskId + "> TICK TICK" + i);
try {
TimeUnit.MILLISECONDS.sleep(sleepTime);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("#### <" + currentThreadName + "," + taskId + "> done...####");
}
public MyRunnableTask(long sleepTime) {
this.id = ++count;
this.taskId = "MyRunnableTask" + id;
this.sleepTime = sleepTime;
}
}
결과는 다음과 같다.
[main] thread starts here...
#### <MyThread-1,MyRunnableTask1> starting...####
<MyThread-1,MyRunnableTask1> TICK TICK0
<MyThread-1,MyRunnableTask1> TICK TICK1
<MyThread-1,MyRunnableTask1> TICK TICK2
Task completion : false
<MyThread-1,MyRunnableTask1> TICK TICK3
#### <MyThread-1,MyRunnableTask1> done...####
Task completion : true
Task completion : true
Task completion : true
[main] thread ends here...
참고로 Future
近期评论