How many timers?

[William Stacey [MVP]]

How many System.Threading.Timer timers can os "reasonably" handle? What is
the cost in mem? I think this is a wraper for win32 TimerQueueTimer (not
sure), but wonder what general implementation is. A queue of objects that
one thread keeps checking to see it time expired, etc. TIA

 

[Richard Blewett [DevelopMentor]]

System.Timers.Timer is a wrapper for the NT Waitable Timer.

System.Threading.Timer is a CLR threadpool based timer which fires its events on threadpool thread. I just looked in reflector to find out the implementation details but unfortunately the crucial method AddTimerNative is marked as internalcall.

I'll have to have a dig in the ROTOR code and see.

Regards

Richard Blewett - DevelopMentor

http://staff.develop.com/richardb/weblog

nntp://news.microsoft.com/microsoft.public.dotnet.languages.csharp/<[email protected]>

How many System.Threading.Timer timers can os "reasonably" handle? What is
the cost in mem? I think this is a wraper for win32 TimerQueueTimer (not
sure), but wonder what general implementation is. A queue of objects that
one thread keeps checking to see it time expired, etc. TIA

--
William Stacey, MVP



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[Willy Denoyette [MVP]]

Richard,

You are right, System.Threading.Timer takes advantage (on W2K, XP and W2K3 -
don't know about other OSses) of the OS "TimerQueue" threadpool.
By default, this thread pool has a maximum of 500 threads, as far I can see
the CLR (v1.1) doesn't change this value.
One CLR System.Threading.Timer maps onto one "timer queue timer by(calling
Win32 CreateTimerQueueTimer), so we can assume the maximum is 500.

Willy.