It’s presumably not a small degradation - this guy very recently suggested it’s
77% slower:
https://blog.packagecloud.io/eng/2017/03/08/system-calls-are-much-slower-on-ec2/
The other reason that blog post is interesting to me is that his benchmark
utility showed the work of entering the kernel as high system time, which is
also what I was seeing.
I really want to go back and try some more tests, including (now) disabling the
timeAllowed param in my query corpus.
I think I’m still a few weeks of higher priority issues away from that though.
On 5/2/17, 1:45 PM, "Tomás Fernández Löbbe" <tomasflo...@gmail.com> wrote:
I remember seeing some performance impact (even when not using it) and it
was attributed to the calls to System.nanoTime. See SOLR-7875 and SOLR-7876
(fixed for 5.3 and 5.4). Those two Jiras fix the impact when timeAllowed is
not used, but I don't know if there were more changes to improve the
performance of the feature itself. The problem was that System.nanoTime may
be called too many times on indices with many different terms. If this is
the problem Jeff is seeing, a small degradation of System.nanoTime could
have a big impact.
Tomás
On Tue, May 2, 2017 at 10:23 AM, Walter Underwood <wun...@wunderwood.org>
wrote:
> Hmm, has anyone measured the overhead of timeAllowed? We use it all the
> time.
>
> If nobody has, I’ll run a benchmark with and without it.
>
> wunder
> Walter Underwood
> wun...@wunderwood.org
>
https://linkprotect.cudasvc.com/url?a=http://observer.wunderwood.org/&c=E,1,7uGY1VtJPqam-MhMKpspcb31C9NQ_Jh4nI0gzkQP4gVJkhcC5l031vMIHH0j38EdMESOM5Chjav3lUu1rpTdohTNTPdchTkl4TGNEHWJpJFJ-MR6RrjnTQ,,&typo=0
(my blog)
>
>
> > On May 2, 2017, at 9:52 AM, Chris Hostetter <hossman_luc...@fucit.org>
> wrote:
> >
> >
> > : I specify a timeout on all queries, ....
> >
> > Ah -- ok, yeah -- you mean using "timeAllowed" correct?
> >
> > If the root issue you were seeing is in fact clocksource related,
> > then using timeAllowed would probably be a significant compounding
> > factor there since it would involve a lot of time checks in a single
> > request (even w/o any debugging enabled)
> >
> > (did your coworker's experiements with ES use any sort of equivilent
> > timeout feature?)
> >
> >
> >
> >
> >
> > -Hoss
> >
https://linkprotect.cudasvc.com/url?a=http://www.lucidworks.com/&c=E,1,DwDibSb7PG6wpqsnn-u9uKdCuujyokjeyc6ero6bEdoUjs4Hn_X1jj_z6QAEDmorDqAP_TcaEJX8k5HYYJI7bJ7jQxTDpKUX9MvWAaP6ICoyVmpmQ8X7&typo=0
>
>
