timedtask.java

import java.util.Random;
import java.util.concurrent.*;
import java.util.Vector;

public class Main  {
    static class TimeConsumingTask implements Runnable {
      public Vector<Integer> results = new Vector<>();
      
      @Override
      public void run() {
          System.out.println("Task thread: " + Thread.currentThread().getName());
          System.out.println("Running time consuming task: " + System.currentTimeMillis());

          try {
            doSomething(0);
          } catch(Exception e) {
            System.out.println("[Thread " + Thread.currentThread().getName() + "] Exception caught. Printing stack trace ...");
            e.printStackTrace();
            System.out.println("[Thread " + Thread.currentThread().getName() + "] Exit.");
            return;
          }         
      }
      
      private int doSomething(int depth) throws Exception {
          final long total_ints = 1<<20;
          if(depth == 5) {
            long numbers_to_gen = total_ints / (1<<depth);
            int sum = 0;
            for(int j=0;j<numbers_to_gen;++j) {
              // Check if the thread is interrupted frequently
              if(Thread.currentThread().isInterrupted()) throw new Exception("Compute task interrupted.");
              sum += (new Random()).nextInt(2);
            }
            return sum;
          } else if(depth == 0) {
            for(int i=0;i<100;++i) {
              int sum = doSomething(depth+1) + doSomething(depth+1);
              results.add(sum);
              System.out.println("[Thread " + Thread.currentThread().getName() + "] Finished " + String.valueOf(i) + " / 100 @ " + System.currentTimeMillis());
              System.out.println("[Thread " + Thread.currentThread().getName() + "] Current sum = " + sum);
            }
            return 0;
          } else {
            return doSomething(depth+1) + doSomething(depth+1);
          }
      }
    }
  
    public static void main(String[] args) {
        System.out.println("Main thread: " + Thread.currentThread().getName());

        long time_limit = (new Random()).nextInt(1000) + 500;
        System.out.println("Timer limit: " + time_limit);

        TimeConsumingTask compute_task = new TimeConsumingTask();
        Thread compute_thread = new Thread(compute_task);
        
        System.out.println("Begin: " + System.currentTimeMillis());
        long start_time = System.currentTimeMillis();
        compute_thread.start();

        try {        
          // Don't over sleep
          while((System.currentTimeMillis() - start_time) < time_limit * 0.98) {
            // Sleep for some time
            long elapsed_time = System.currentTimeMillis() - start_time;
            long remaining_time = time_limit - elapsed_time;
            long sleep_time = (long)Math.min(time_limit * 0.05, remaining_time * 0.9);
            System.out.println("[Thread " + Thread.currentThread().getName() + "] Elapsed time: " + elapsed_time + ", Sleep for " + sleep_time + " ms");
            Thread.currentThread().sleep(sleep_time);
          }
          compute_thread.interrupt();
          compute_thread.join();
        } catch(InterruptedException e){
          e.printStackTrace();
        } finally {
          
        }
        long end_time = System.currentTimeMillis();
        System.out.println("[Thread " + Thread.currentThread().getName() + "] Compute task ended: " + end_time);
        System.out.println("[Thread " + Thread.currentThread().getName() + "] Total time used: " + (end_time - start_time));
        
        System.out.println("[Thread " + Thread.currentThread().getName() + "] Finding the maximum sum ...");
        int maxval = 0;
        for(int i=0;i<compute_task.results.size();++i) {
          maxval = Math.max(maxval, compute_task.results.get(i));
        }
        System.out.println("[Thread " + Thread.currentThread().getName() + "] Max sum = " + maxval);
        System.exit(0);
    }
}