I am having following code:
public class ExecFramework implements Runnable {
int i;
public ExecFramework() {
}
public ExecFramework(int i) {
this.i = i;
}
public void run() {
System.out.println(Thread.currentThread().getName() + " " + i);
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
ExecutorService pool=new ThreadPoolExecutor(2, 10, 5000,TimeUnit.SECONDS, new ArrayBlockingQueue(2));
for (int i = 0; i < 20; i++) {
Runnable obj=new ExecFramework(i);
pool.execute(obj);
}
pool.shutdown();
while(pool.isTerminated()){
System.out.println("ExecutorService is terminated");
}
}
}
Is my knowledge for the way ThreadPoolExecutor works correct:
- If NumberOfThreadRunning < CoreNumberOfThreads then ThreadPoolExecutor creates a new thread to complete the task.
- If NumberOfThreadRunning > CoreNumberOfThreads then queue this task in BlockingQueue but if queue is full then create a new Thread only if NumberOfThread < MaxNumberOfThreads.
- Once the task is completed thread running that task is available for other task.
According to 3rd point. I should be able to execute 20 tasks using ThreadPoolExecutor.
Why Output of above code is?
pool-1-thread-5 6
pool-1-thread-4 5
pool-1-thread-3 4
pool-1-thread-1 0
pool-1-thread-2 1
pool-1-thread-6 7
pool-1-thread-7 8
pool-1-thread-8 9
pool-1-thread-9 10
pool-1-thread-10 11
Exception in thread "main" java.util.concurrent.RejectedExecutionException: Task executionFramework.ExecFramework@232204a1 rejected from java.util.concurrent.ThreadPoolExecutor@4aa298b7[Running, pool size = 10, active threads = 10, queued tasks = 2, completed tasks = 0]
at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
at executionFramework.ExecFramework.main(ExecFramework.java:88)
pool-1-thread-8 2
pool-1-thread-6 3