Multi Threading

Question

Hi

How I can get to know which thread is waiting for more time?

My requirement is, In a synchronized methos, when one thread completes its task, I want to allow the Thread which is waiting for long time. I hope my question make sense.

Answer 1

All depends on which language and/or environment you are using. So far as I know there's no intrinsic support for this in Java, if multiple threads are waiting to enter a synchronized method then the system will pick an arbitrary one to run when entry is possible.

If instead you use Java's wait() / notify() then you control which threads are notified and so can build your own priority mechanism, for example you could have a simple queue to which each thread adds itself before its wait() then you just take the top item from the queue and notify that thread.

Answer 2

You should not and almost certainly do not need to do this.

The threading environment will schedule threads for you.

If the software design is such that this appears to be a problem, then the design is incorrect for a pre-emptive threading environment.

What you may want to be doing is something more like managing and prioritizing units of work, where you for example service work in the order that it arrives.

In other words, the order of work processing should not in your design depend on which thread runs, but rather, on your design of how work is handed out to threads.