From: Michael Fischer <firstname.lastname@example.org> To: Sarkis Varozian <email@example.com> Cc: unicorn-public <firstname.lastname@example.org> Subject: Re: Request Queueing after deploy + USR2 restart Date: Wed, 4 Mar 2015 11:51:46 -0800 [thread overview] Message-ID: <CABHxtY5XU_cyda8JzZYJZCYB3GNfusS7z4jSP9k6V15AKNutFg@mail.gmail.com> (raw) In-Reply-To: <CAGchx-KX-UPcxMfidfxqgsDLy11HEOg3Dsca0-QvpekHBs5kkA@mail.gmail.com> What does your I/O latency look like during this interval? (iostat -xk 10, look at the busy %). I'm willing to bet the request queueing is strongly correlated with I/O load. Also is preload_app set to true? This should help. --Michael On Wed, Mar 4, 2015 at 11:48 AM, Sarkis Varozian <email@example.com> wrote: > Michael, > > Thanks for this - I have since changed the way we are restarting the > unicorn servers after a deploy by changing capistrano task to do: > > in :sequence, wait: 30 > > We have 4 backends and the above will restart them sequentially, waiting > 30s (which I think should be more than enough time), however, I still get > the following latency spikes after a deploy: http://goo.gl/tYnLUJ > > This is what the individual servers look like for the same time interval: > http://goo.gl/x7KcKq > > > > On Tue, Mar 3, 2015 at 2:32 PM, Michael Fischer <firstname.lastname@example.org> > wrote: > >> If the response times are falling a minute or so after the reload, I'd >> chalk it up to a cold CPU cache. You will probably want to stagger your >> reloads across backends to minimize the impact. >> >> --Michael >> >> On Tue, Mar 3, 2015 at 2:24 PM, Sarkis Varozian <email@example.com> >> wrote: >> >>> We have a rails application with the following unicorn.rb: >>> http://goo.gl/qZ5NLn >>> >>> When we deploy to the application, a USR2 signal is sent to the unicorn >>> master which spins up a new master and we use the before_fork in the >>> unicorn.rb config above to send signals to the old master as the new >>> workers come online. >>> >>> I've been trying to debug a weird issue that manifests as "Request >>> Queueing" in our Newrelic APM. The graph shows what happens after a >>> deployment (represented by the vertical lines). Here is the graph: >>> http://goo.gl/iFZPMv . As you see from the graph, it is inconsistent - >>> there is always a latency spike - however, at times Request Queueing is >>> higher than previous deploys. >>> >>> Any ideas on what exactly is going on here? Any suggestions on >>> tools/profilers to use to get to the bottom of this? Should we expect >>> this >>> to happen on each deploy? >>> >>> Thanks, >>> >>> -- >>> *Sarkis Varozian* >>> firstname.lastname@example.org >>> >>> >>> >> > > > -- > *Sarkis Varozian* > email@example.com >
next prev parent reply other threads:[~2015-03-04 19:51 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-03-03 22:24 Sarkis Varozian 2015-03-03 22:32 ` Michael Fischer 2015-03-04 19:48 ` Sarkis Varozian 2015-03-04 19:51 ` Michael Fischer [this message] 2015-03-04 19:58 ` Sarkis Varozian 2015-03-04 20:17 ` Michael Fischer 2015-03-04 20:24 ` Sarkis Varozian 2015-03-04 20:27 ` Michael Fischer 2015-03-04 20:35 ` Eric Wong 2015-03-04 20:40 ` Sarkis Varozian 2015-03-05 17:07 ` Sarkis Varozian 2015-03-05 17:13 ` Bráulio Bhavamitra 2015-03-05 17:28 ` Sarkis Varozian 2015-03-05 17:31 ` Bráulio Bhavamitra 2015-03-05 17:32 ` Bráulio Bhavamitra 2015-03-05 21:12 ` Eric Wong 2015-03-03 22:47 ` Bráulio Bhavamitra 2015-03-04 19:50 ` Sarkis Varozian [not found] ` <CAJri6_vidE15Xor4THzQB3uxyqPdApxHoyWp47NAG8m8TQuw0Q@mail.gmail.com> 2015-09-13 15:12 ` Bráulio Bhavamitra 2015-09-14 2:14 ` Eric Wong
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