From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on dcvr.yhbt.net X-Spam-Level: * X-Spam-ASN: AS33070 50.56.128.0/17 X-Spam-Status: No, score=1.1 required=3.0 tests=AWL,HK_RANDOM_FROM, MSGID_FROM_MTA_HEADER,PLING_QUERY,TVD_RCVD_IP shortcircuit=no autolearn=no version=3.3.2 Path: news.gmane.org!not-for-mail From: Eric Wong Newsgroups: gmane.comp.lang.ruby.rainbows.general Subject: Re: Rainbows! + EventMachine + Sinatra::Synchrony == pegged CPU when idle? Date: Tue, 19 Jun 2012 17:54:09 +0000 Message-ID: <20120619175409.GA27303@dcvr.yhbt.net> References: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Trace: dough.gmane.org 1340128461 2481 80.91.229.3 (19 Jun 2012 17:54:21 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Tue, 19 Jun 2012 17:54:21 +0000 (UTC) To: Rainbows! list Original-X-From: rainbows-talk-bounces-GrnCvJ7WPxnNLxjTenLetw@public.gmane.org Tue Jun 19 19:54:20 2012 Return-path: Envelope-to: gclrrg-rainbows-talk@m.gmane.org X-Original-To: rainbows-talk-GrnCvJ7WPxnNLxjTenLetw@public.gmane.org Delivered-To: rainbows-talk-GrnCvJ7WPxnNLxjTenLetw@public.gmane.org Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-BeenThere: rainbows-talk-GrnCvJ7WPxnNLxjTenLetw@public.gmane.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: rainbows-talk-bounces-GrnCvJ7WPxnNLxjTenLetw@public.gmane.org Errors-To: rainbows-talk-bounces-GrnCvJ7WPxnNLxjTenLetw@public.gmane.org Xref: news.gmane.org gmane.comp.lang.ruby.rainbows.general:367 Archived-At: Received: from 50-56-192-79.static.cloud-ips.com ([50.56.192.79] helo=rubyforge.org) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Sh2d5-0000AG-Cz for gclrrg-rainbows-talk@m.gmane.org; Tue, 19 Jun 2012 19:54:15 +0200 Received: from localhost.localdomain (localhost [127.0.0.1]) by rubyforge.org (Postfix) with ESMTP id 7E3C52E063; Tue, 19 Jun 2012 17:54:14 +0000 (UTC) Received: from dcvr.yhbt.net (dcvr.yhbt.net [64.71.152.64]) by rubyforge.org (Postfix) with ESMTP id 202522E060 for ; Tue, 19 Jun 2012 17:54:10 +0000 (UTC) Received: from localhost (dcvr.yhbt.net [127.0.0.1]) by dcvr.yhbt.net (Postfix) with ESMTP id C981A354FC; Tue, 19 Jun 2012 17:54:09 +0000 (UTC) Ilya Maykov wrote: > Hi all, > > We're using Rainbows + EventMachine + Sinatra::Synchrony to run a > fleet of RESTful web servers backed by a Cassandra cluster. We are > using the EventMachineTransport to talk to Cassandra with an > EM::Synchrony::ConnectionPool in each rainbows worker. We have a Storm > cluster pushing a large stream of real-time data into the Rainbows > fleet using HTTP PUT requests. We're running into some very strange > performance issues and need help figuring out what's going on. I'm not at all familiar with Storm nor Cassandra. How big are the HTTP PUT requests Rainbows! is getting? Is Storm pipelining HTTP requests by any chance? That may not do well with the EM portion of Rainbows! > Basically, when load is low, everything looks good. When we crank up > the load, all of a sudden the CPU gets pegged, request latencies go > waaaay up, and requests start timing out. Once this state is reached, > the high CPU usage (4 rainbows worker processes at ~50% each on a > 2-core machine = nearly full load) remains even if we completely shut > off all incoming traffic. > Taking a look with strace -p, it looks like > the rainbows processes are writing ascii NUL characters to file > descriptor 7 (which is a FIFO) as fast as the kernel will let them. My > guess is that the worker is trying to communicate with the rainbows > master process via the FIFO. No, rainbows doesn't have code to send "\0" to the master. I don't think EM does, either, maybe some other library you're using... Which version of Ruby is this? Try adding "-f" to follow threads for a worker. > Not sure what is triggering this > behavior, but would like to know if anyone else has ever seen > something like this. This thread sounded like it could've been a > similar issue, but died out without any conclusion: > http://rubyforge.org/pipermail/rainbows-talk/2012-April/000345.html > > Some details about the setup: > > 6-node cassandra cluster > 3 nodes running rainbows web servers > 4 rainbows workers per node > max of 50 cassandra connections per rainbows worker > rainbows.conf has: > > Rainbows! do > use :EventMachine > worker_connections 50 > keepalive_requests 1000 > keepalive_timeout 10 > end Do you have preload_app set to true anywhere? (Try leaving it as false (the default)) Can you also try "keepalive_timeout 0" to disable keepalive? (EM handles it internally, but I'm not sure how well) > So, each rainbows node can handle 4 * 50 = 200 simultaneous connections > > 12 Storm worker processes writing to the rainbows web servers > each Storm worker has max of 10 connections open to each of the 3 rainbows nodes > > So, each rainbows node has 12 * 10 = 120 incoming connections from Storm. > > Have been playing around with the numbers, the bug (assuming it is a > bug) seems to be easier to trigger when I increase the number of > incoming connections (from Storm workers), even if they are a lot less > than the rainbows servers can take (60-70% of the max connections is > usually enough). The bug is also easier to trigger when we increase > the volume of data we're pushing through Storm - hundreds or thousands > of requests per minute, no bug - hundreds of thousands of requests per > minute, yes bug. Cassandra is not the issue, it can easily take the > write load we're generating and is basically idle. > > Any help in figuring this out would be greatly appreciated. Thanks, Try my suggestions above. I would also search your libs/gems for what's writing "\0" since I don't think it's Rainbows!... _______________________________________________ Rainbows! mailing list - rainbows-talk-GrnCvJ7WPxnNLxjTenLetw@public.gmane.org http://rubyforge.org/mailman/listinfo/rainbows-talk Do not quote signatures (like this one) or top post when replying