Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

What if a timer can not finish all its works before the new cycle time arrives?

Suppose we have a timer which runs every 10 minutes. What if the cycle of its processing takes more than 10 minutes. Does a new thread starts for that? Will it interrupt its current operation? What if a single object is mutated inside the timer?

Sorry if I do not mention any code for that because the problem is clear and also I want to know the complete answer from the viewpoint of a multi-threaded programming geek rather than finding a loose answer by trying to test it via a sample application. Actually, I want to know the logic behind its working mechanism.

like image 477
Farshid Avatar asked May 06 '12 14:05

Farshid


3 Answers

If you're using System.Threading.Timer or System.Timers.Timer, the timer will tick again, starting a new thread. See https://stackoverflow.com/a/10442117/56778 for a way to avoid that problem.

If you're using System.Windows.Forms.Timer, then a new tick won't occur until the previous one is finished processing.

like image 95
Jim Mischel Avatar answered Oct 30 '22 15:10

Jim Mischel


Put your code in a Monitor.TryEnter()

object timeCheck= new object();

void Timer()
{
    Monitor.TryEnter(timeCheck) 
    {
        //Code that might take too long 
        //...
        Monitor.Exit();
    }
}
like image 22
rare Avatar answered Oct 30 '22 15:10

rare


to prevent reentrancy, you might use a static boolean that tells wether the function is allready beeing executed. User a try/Catch/finally and set this boolean to false in the finally to ensure that the boolean does not remain false if you made a mistake in code or if the code failed.
For a faster timer, reentrancy should be prevented by using semaphore (mutex).

like image 1
GameAlchemist Avatar answered Oct 30 '22 16:10

GameAlchemist