From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS15169 209.85.128.0/17 X-Spam-Status: No, score=-0.9 required=3.0 tests=AWL,BAYES_00,FREEMAIL_FROM, URIBL_BLOCKED,URIBL_DBL_ABUSE_REDIR shortcircuit=no autolearn=ham version=3.3.2 X-Original-To: unicorn-public@bogomips.org Received: from mail-ie0-f171.google.com (mail-ie0-f171.google.com [209.85.223.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 7FC6D1F49F for ; Wed, 4 Mar 2015 19:58:16 +0000 (UTC) Received: by iecrd18 with SMTP id rd18so70209342iec.5 for ; Wed, 04 Mar 2015 11:58:15 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.50.79.229 with SMTP id m5mr40808349igx.23.1425499094871; Wed, 04 Mar 2015 11:58:14 -0800 (PST) Received: by 10.107.43.73 with HTTP; Wed, 4 Mar 2015 11:58:14 -0800 (PST) In-Reply-To: References: Date: Wed, 4 Mar 2015 11:58:14 -0800 Message-ID: Subject: Re: Request Queueing after deploy + USR2 restart From: Sarkis Varozian To: Michael Fischer Cc: unicorn-public Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: PublicInbox::Filter 0.0.1 List-Id: Yes, preload_app is set to true, I have not made any changes to the unicorn.rb from OP: http://goo.gl/qZ5NLn Hmmmm, you may be onto something - Here is the i/o metrics from the server with the highest response times: http://goo.gl/0HyUYt (in this graph: http://goo.gl/x7KcKq) Looks like it may be i/o related as you suspect - is there much I can do to alleviate that? On Wed, Mar 4, 2015 at 11:51 AM, Michael Fischer wrote: > 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 > 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 >> 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 >>> 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* >>>> svarozian@gmail.com >>>> >>>> >>>> >>> >> >> >> -- >> *Sarkis Varozian* >> svarozian@gmail.com >> > > -- *Sarkis Varozian* svarozian@gmail.com