[rrd-developers] rrdcached BATCH not flushed

[Anthony Molinaro]

Well I 'solved' part of my problem, turns out the parsing I was doing
in perl was super slow.  So swapping in a C program to parse the 
file and piping to perl to write via RRDs::update via the daemon works
a lot better now.  I'm hitting 150000 rrds in about 20 seconds or so
so I should be good for 2-3x my current number.

However, I'm still wondering why BATCH and flush didn't seem to work
together, so still curious about that.

Thanks,

-Anthony

On Thu, Apr 12, 2012 at 09:33:42AM -0700, Anthony Molinaro wrote:
> Hi,
> 
>   I have a large rrd setup which currently seems to only be able to handle
> about 150000 rrds.  My setup involves capturing some UDP packets with
> information about metrics and each minute writing those to rrds via
> rrdcached.
> 
> Basically the code looks like
> 
>   while (!done) {
>     read packet from file
>     foreach metric in packet {
>       RRDs::update ($file, "$timestamp:$metric_value",
>                     "--daemon", "/var/run/rrdcached.sock");
>     }
>   }
> 
> rrdcached is run as
> 
>   rrdcached -l /var/run/rrdcached.sock -w 3600 -f 7200 \
>             -p /var/run/rrdcached.pid
> 
> I have a file each minute and attempt to load the previous minutes file.
> At about 150000 rrds it starts taking more than a minute.
> 
> I thought I might be able to speed it up by connecting directly to the
> daemon socket and using the BATCH command.
> 
> So I changed my code to buffer up a set of updates, do something like
> 
>   my $name="/var/run/rrdcached.sock";
>   my $client = IO::Socket::UNIX->new(Peer => $name,
>                                      Type => SOCK_STREAM) or die "socket: $!";
>   print $client "BATCH\n";
>   $client->flush;
>   foreach my $update (@updates) {
>     print $client $update;
>   }
>   $client->flush;
>   print $client ".\n";
>   $client->flush;
>   print $client "QUIT\n";
>   $client->flush;
>   $client->close;
> 
> Which seems marginally faster (shaved about 10 seconds), however the real
> issue is that flushes at the graphing layer don't seem to work when I use
> this approach.  With the prior approach viewing graphs seemed to cause
> flushes in that the data was always up to date.  With the latter approach
> they do not get flushed until you send a FLUSHALL or I guess the flush timer
> expires.
> 
> Has anyone else experienced this?  Does anyone have any recommendations
> for alternate approaches?  If I were to have multiple clients calling
> RRDs::update from say different threads would that help?
> 
> I'm using rrdtool 1.4.5 on Centos 5.4.
> 
> Thanks,
> 
> -Anthony
> 
> -- 
> ------------------------------------------------------------------------
> Anthony Molinaro                           <anthonym at alumni.caltech.edu>
> 
> _______________________________________________
> rrd-developers mailing list
> rrd-developers at lists.oetiker.ch
> https://lists.oetiker.ch/cgi-bin/listinfo/rrd-developers

-- 
------------------------------------------------------------------------
Anthony Molinaro                           <anthonym at alumni.caltech.edu>