RFC: New IPC Method for Check Results

[Hendrik Bäcker]

Ethan Galstad wrote:
> Proposed solution:
>
> The new method I am proposing is simple and straightforward.  Why I 
> didn't implement something like this years ago is beyond me. :-)
>   
Cause, you just wanted to begin your programmers way with a pipe?? *just
kidding*
> Instead of passing check results from child processes to the main Nagios 
> process via two methods (pipe and file), I suggest that all information 
> be written to files in a special check result queue directory (e.g., 
> var/checkresults).  Child processes that perform host/service checks can 
> write all results to a file in the queue directory.  The main Nagios 
> process will then periodically process all files/check results in the 
> queue in a time-ordered fasion.
>   
Some of us will remember my post about "a good way to handle performance
data" with a small discussion about pipes vs. "spooldirs"?!
In the actual release of the PNP Addon we have established a small
daemon that does exactly what you wrote above.
Short excurs: Nagios writes only files with perfdata, rotate them every
x seconds to a spool dir, daemon reads the files and process them to
fill the rrdfiles.
This solution brought me from a latency around 350 Seconds ( ~ 2000
Serviceechecks) down to 2-5 seconds.

Cause of this I would say: this is the right way.
>
> Any performance hits that may occur with the new IPC method due to disk 
> thrashing can be minimized if the queue directory is placed on a 
> memory-mapped filesystem.  Whether this will actually be necessary or 
> not in all but the largest installations remains to be seen.
>   
I would suggest to keep an eye on the number of files within a
directory. I know some guys with a huge number of distributed nagios
servers and a big amount of service checks.
It might be bad if nagios dies for hours and on re-awakening to process
thousand of single files if you think of using one file for each result.

Just my 2 Cents.

Kind regards
Hendrik

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