Spring Scheduler synchronized method starvation

Question

Assume I have a scheduler

@Component
public class Scheduler{

    private static int counter = 0;

    private synchronized void countIt(){
        counter++;
    }

    @Scheduled(fixedDelay = 3000)
    public void job1(){
        countIt();
    }

    @Scheduled(fixedDelay = 6000)
    public void job2(){
        countIt();
    }
}

Different task trigger in different case will call countIt.

When two or more job call countIt simultaneous, it will cause starvation.

Could any one tell me if there is a way to avoid this situation?

@AdamSkywalker the real case is a little complicated. I have lots of threads call this synchronized method. When they call the method in the same time, deadlock happened. — Roy, Oct 14 '16 at 12:17
deadlock is a situation when thread 1 holds resource A and needs resource B, and thread 2 holds resource B and needs resource A. synchronized method is a mutex, alone it can't cause a deadlock — AdamSkywalker, Oct 14 '16 at 12:21
maybe your thread got stuck inside a method and other threads are waiting for it, but it's not a deadlock — AdamSkywalker, Oct 14 '16 at 12:22
At the most, this could cause starvation, but not a deadlock. — Haroldo_OK, Oct 14 '16 at 12:30
@AdamSkywalker I think I use a wrong word, as Haroldo_OK figure out, it is starvation. — Roy, Oct 14 '16 at 12:41

score 0 · Answer 1 · answered Oct 14 '16 at 12:27

This should not deadlock.

A Deadlock is caused by one thread locking resource A and then attempting to lock resource B while another thread locks resource B and then tries to lock resource A. There are more complex ways a deadlock can occurr but deadlocks cannot happen with only one lock.

In your case there is only one lock so there is no deadlock.

score 0 · Accepted Answer · answered Oct 14 '16 at 13:50

0

There is no deadlock here!

Use ReetrantLock with Fair policy. if u dont know ReentrantLock please google it.

private final ReentrantLock lock = new ReentrantLock(true);

answered Oct 14 '16 at 13:50

Ugur Tufekci

350
2
13

It seems what I looking for, Let me try it first – Roy Oct 14 '16 at 15:48

Spring Scheduler synchronized method starvation

2 Answers2