[rrd-users] Re: Heavy-Duty RRD Usage

[Tobias Oetiker]

Today Chris Snell wrote:

>
> Hi All,
>
> I've set up RRDtool and a heavily-modified version of Bronc here to do
> some performance and usage graphing.  Currently, I'm monitoring about
> 1200 hosts with many more to come.  All was going well until today when
> I attempted to make some graphs which showed utilization of an entire
> server farm for a project.  To do this, I have a massive CDEF that adds
> up (for example) web hits from 200 different RRD files and displays them
> in a single graph.  I'm running this under Apache/mod_perl using RRDs.
>  While it /does/ work, the memory usage of the Apache processes is
> unacceptable--roughly 170M per child.  Before I started combining many
> RRD files into one graph, memory usage was down around 15M per child.
>  My question: when RRDs is run under mod_perl, does it clean up its
> memory after each call to RRDs::graph?  Does anyone have any suggestions
> for ways to slim down these processes?  I don't mind if they use this
> much memory while generating a graph but when they are finished with
> that, the memory needs to be freed.

rrdtool loads ALL the data it uses to build the graph into memory
... and because processes can not give back any memory they can not
shrink ...

I suggest you use speedyCGI to run bronc. This will make sure your
appache processes to not get hurt ...

If you are using wide rrds (many DS) memory consumption will also
be higher because rrdtool graph keeps data for all DS in memory not
only for the one you selected ... this could be improved by
modifying rrdtool graph and potentially rrdtool fetch

tobi
>
> take care,
>
> Chris
>
>
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