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: AS14135 216.205.24.0/21 X-Spam-Status: No, score=-0.4 required=3.0 tests=AWL,BAYES_00,URIBL_BLOCKED, URIBL_DBL_ABUSE_REDIR shortcircuit=no autolearn=ham version=3.3.2 X-Original-To: unicorn-public@bogomips.org Received: from us-smtp-delivery-110.mimecast.com (us-smtp-delivery-110.mimecast.com [216.205.24.110]) by dcvr.yhbt.net (Postfix) with ESMTP id 66E961F49F for ; Wed, 4 Mar 2015 19:51:49 +0000 (UTC) Subject: Re: Request Queueing after deploy + USR2 restart Received: from mail-qa0-f46.google.com (mail-qa0-f46.google.com [209.85.216.46]) (Using TLS) by us-mta-7.us.mimecast.lan; Wed, 04 Mar 2015 14:51:47 -0500 Received: by mail-qa0-f46.google.com with SMTP id n4so35591873qaq.5 for ; Wed, 04 Mar 2015 11:51:46 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=Hkf2Vbi+tgdoi0meFT01MtJjmPLvAkSqyPGRMg6O8zU=; b=U8GvVJJ7wCAGHj6CLoRQz1BFl2d23izrNY7M5Mhf5P/m7oJ5qbMc14KJb1UtpDqjgF cjQYlqwiOI7G1SVXaGMipGxe/pKutJAIcYzHOqQIqKGnYJ59Kw53CUQ+vZoIdpE614gR qI6ZJn59GuN72vwAGE997SXD4bMV+ZjE9unE8pNHhMcNsNWeFCG+X1+sWZy7qdpabHuO uvqhf/4JNFTcat8LDkaNxBgkPdf9J2/9rnuSbv67YvLaQl0J7HFFwYIgqI+/S0CAD66I o6NbZNnf0ZMKED/3NX1f43APzHfEARmOJsBNLoTn/Y9ru+atDT51E9ur7PS5W+27WMXQ rHKA== X-Gm-Message-State: ALoCoQnpFGr5OA4dHHpDKZJvDYuULDpjfNF7if61UUlYaOObwnKzdK/+8cL1q1cigBSxKi/R5TU4hCn7nPYuROjT8Aqa4nFIVbppyFwWF6DRhIECxXY85HoCNH5ttB/NpWlmO1CVzBDdpavwGBA5dLwbI3K0m0n+trpXQ8ZZwPxxE6KjvlcYMkY= X-Received: by 10.55.22.32 with SMTP id g32mr6057800qkh.4.1425498706464; Wed, 04 Mar 2015 11:51:46 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.55.22.32 with SMTP id g32mr6057784qkh.4.1425498706364; Wed, 04 Mar 2015 11:51:46 -0800 (PST) Received: by 10.140.48.97 with HTTP; Wed, 4 Mar 2015 11:51:46 -0800 (PST) In-Reply-To: References: Date: Wed, 4 Mar 2015 11:51:46 -0800 Message-ID: From: Michael Fischer To: Sarkis Varozian Cc: unicorn-public X-MC-Unique: 3HMrDYb1TeG8RJSwhXS3FQ-1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: PublicInbox::Filter 0.0.1 List-Id: 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 >