More Threads Please?

[Steven D. Morrey]

Hello Everyone,

I've been profiling Nagios and found that at least on my installation with 30,000+ checks  that 60% of the time is spent in reaping events and 3% is spent in saving status and another 1%  is spent in writing out retention files.
This means that less than 30% is actually spent executing checks, to compound the problem the latency is really, really high and it looks like it's due to high priority events blocking execution.
It seems to me that all of these "high priority" events are high priority because they need to run right now, but I don't see why they need to block execution of everything else just to perform housekeeping tasks.

Assuming I were to put a mutex on the relevant objects, can anyone foresee a problem with running these high priority events in their own thread or even threads?

I have 2 designs in mind.
One would be a simple refactor that calls handle_timed_event with pthread create, on the high priority events.
This would create a new thread for each high priority event, but would be literally be a change to only a couple lines of code.

Another design would call for a breaking the main event loop into a high priority thread and a low priority thread.  
In this case we would only have 2 threads, we loose a bit of the flexibility (and danger) and of having per event threads for high priority events, we also loose most of  the overhead of thread creation.

I'm not sure high priority events are frequent enough that thread creation overhead is significant.

Anyways, as always your thoughts are very much appreciated.


 NOTICE: This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message.



------------------------------------------------------------------------------
Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day 
trial. Simplify your report design, integration and deployment - and focus on 
what you do best, core application coding. Discover what's new with 
Crystal Reports now.  http://p.sf.net/sfu/bobj-july