[rrd-users] major remote performance regression for rrdcached 1.5

[Steven Hartland]

Ok found the cause, does seem FETCH support was added rrdcached in 1.5 
and Nagle wasn't being disabled on the network socket so every request 
was seeing a 0.1 second delay in completion.

PR to fix can be found here: https://github.com/oetiker/rrdtool-1.x/pull/706

Testing here showed this dropped our test of 862 fetches from 91.338 
seconds to 0.335 seconds :)

     Regards
     Steve

On 10/04/2016 01:43, Steven Hartland wrote:
> We updated to rrdtool 1.5.5 from 1.4 the other day and since then have 
> noticed dramatic slow down.
>
> I just did some benchmarks and talking to rrdcached over a network 
> socket (same host) to do 862 fetches took 91.388106 seconds e.g.
> FETCH 351918.rrd AVERAGE 1460244557 1460244917
>
> The same over local unix socket took 0.097147 seconds so it looks like 
> there's been a major performance regression in 1.5 from 1.4?
>
> When we initially updated the client before our rrdcached server we 
> did see errors with:
> rrdcached: Unknown command: FETCH
>
> So I'm wondering if rrdcached FETCH is new 1.5 hence the issue.
>
> Previously we were running: rrdtool 1.4.8
>
> Anyone got any ideas?
>
>     Regards
>     Steve
>

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