<div dir="ltr">Well, multi-ack didn't help very much. We can see some, but not enough to matter.<div><br></div><div>We cannot use auto-ack because consumers (multiple/server) die unexpectedly as the app servers are autoscaled. We have not built a fully separated service yet (too hard to debug on development machines right now). But could Publisher confirms resolve the issue of servers dying with n messages in their prefetch buffers?<br>
<div><br></div><div><br></div></div></div><div class="gmail_extra"><br clear="all"><div><div dir="ltr"><div><span><font color="#888888">-- <br></font></span><div dir="ltr"><font color="#888888"><span><font color="#888888"><font color="#cc0000" face="georgia, serif" style="font-size:small"><b>Mike Templeman<br>
</b></font><div style="font-family:arial;font-size:small"><b><font face="georgia, serif">Head of Development</font></b><font face="georgia, serif"><br><br></font></div><div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/missdestructo" style="color:rgb(17,85,204)" target="_blank" rel="nofollow" link="external">@talkingfrog1950</a></font></div>
<div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/meshfire" style="color:rgb(17,85,204)" target="_blank" rel="nofollow" link="external">@Meshfire</a></font></div></font></span></font></div>
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<br><br><div class="gmail_quote">On Sun, Dec 15, 2013 at 5:02 AM, Alvaro Videla-2 [via RabbitMQ] <span dir="ltr"><<a href="/user/SendEmail.jtp?type=node&node=32205&i=0" target="_top" rel="nofollow" link="external">[hidden email]</a>></span> wrote:<br>
<blockquote style='border-left:2px solid #CCCCCC;padding:0 1em' class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Hi Mike,<div><br></div><div>Yes, RabbitMQ queues are designed for fast delivery of messages and for being as empty as possible, as that blog post explains.</div><div><br></div><div>Another interesting blog post, about consumer strategies and basic.qos settings is this one: <a href="http://www.rabbitmq.com/blog/2012/05/11/some-queuing-theory-throughput-latency-and-bandwidth/#more-276" rel="nofollow" link="external" target="_blank">http://www.rabbitmq.com/blog/2012/05/11/some-queuing-theory-throughput-latency-and-bandwidth/#more-276</a></div>
<div><br></div><div>re multi ack: yes, that might help.</div><div><br></div><div>Regards,</div><div><br></div><div>Alvaro</div></div><div class="gmail_extra"><br><br><div class="gmail_quote"><div class="im">On Sat, Dec 14, 2013 at 2:15 AM, MikeTempleman <span dir="ltr"><<a href="http://user/SendEmail.jtp?type=node&node=32095&i=0" rel="nofollow" link="external" target="_blank">[hidden email]</a>></span> wrote:<br>
</div><blockquote style='border-left:2px solid #CCCCCC;padding:0 1em' style="border-left:2px solid #cccccc;padding:0 1em" class="gmail_quote"><div class="im"><div dir="ltr">I realized that was a bad interpretation. Sorry. The exchange is just successfully routing all the messages to the target queues.<div>
<br></div><div>After reading a number of posts and this blog entry (<a href="http://www.rabbitmq.com/blog/2011/09/24/sizing-your-rabbits/" rel="nofollow" link="external" target="_blank">http://www.rabbitmq.com/blog/2011/09/24/sizing-your-rabbits/</a>) I wonder if the issue is that each message is ack'd. It seemed that the issue occurred when I had a large backlog in the queues. When Rabbit is empty, performance is fine. When the consumers tried to run at much higher speeds, we encountered this cycling. </div>
<div><br></div><div>We have run a brief test with no-ack, not on production, and the performance is excellent even under load. But this is not a viable solution (appservers crash, autoscaling shuts servers down that have prefetched messages and are still connected to rabbit) without a full redesign.</div>
<div><br></div><div>Assuming each queue is only one thread (I assume it handles both receipt, delivery, and ack cleanup) then I can understand what might happen when the consumers generate ~500 acks/s while new messages are coming in at a low 50-100/s rate on a specific queue. I will move out some events that tend to generate peaks into their own queue and accept that queue processing more slowly. As for separating the real worker queue, I suppose I could create 2 or so static queues to divide the load up.</div>
<div><br></div><div>So what I think I can do is:</div><div>1. bump the default tcp buffer from 128KB to around 10MB. The added buffering may help a little</div><div>2. see if I can find out how to set the multiple ack flag. We are using Grails so maybe that is just creating a custom bean. I don't know</div>
<div>3. create a couple of queues for lower-priority events specifically events chosen to be less time critical.</div><div>4. if all that doesn't work then probably create 4 queues for the high priority events, randomly publish to those queues, and put consumers for each queue.</div>
<div>5. Also, upgrade the server to the latest version.</div><div><br></div><div>Mike Templeman</div></div></div><div class="gmail_extra"><div class="im"><div><br clear="all"><div><div dir="ltr"><div><span><font color="#888888">-- <br>
</font></span><div dir="ltr">
<font color="#888888"><span><font color="#888888"><font color="#cc0000" face="georgia, serif" style="font-size:small"><b>Mike Templeman<br></b></font><div style="font-family:arial;font-size:small"><b><font face="georgia, serif">Head of Development</font></b><font face="georgia, serif"><br>
<br></font></div><div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/missdestructo" style="color:rgb(17,85,204)" rel="nofollow" link="external" target="_blank">@talkingfrog1950</a></font></div>
<div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/meshfire" style="color:rgb(17,85,204)" rel="nofollow" link="external" target="_blank">@Meshfire</a></font></div>
</font></span></font></div>
</div><img><br></div></div>
<br><br></div></div><div class="gmail_quote"><div class="im"><div><div>On Fri, Dec 13, 2013 at 1:42 PM, Mike Templeman <span dir="ltr"><<a href="http://user/SendEmail.jtp?type=node&node=32089&i=0" rel="nofollow" link="external" target="_blank">[hidden email]</a>></span> wrote:<br>
</div></div></div><blockquote style='border-left:2px solid #CCCCCC;padding:0 1em' style="border-left:2px solid #cccccc;padding:0 1em" class="gmail_quote"><div class="im"><div><div>
<div dir="ltr">I noticed something else very odd.<div><br></div><div>Currently, one queue has 43,000 messages backed up in its queue. But when I look at the exchange (there is only one exchange) I see that the message rate in exactly matches the message rate out.</div>
<div><br></div><div>With such a huge backlog, why would that be? I would have thought that the consumers (there are 16 total distributed across 4 systems for that queue with a prefetch of 100) would run at a much higher steady state.</div>
<div><br></div><div>This exchange also seems to cycle regularly. It appears to run from a low of around 60/s in and out to 500+ a second in and out.</div></div></div></div></div><div class="gmail_extra"><div class="im"><div>
<div><div>
<br clear="all"><div>
<div dir="ltr">
<div><span><font color="#888888">-- <br></font></span><div dir="ltr"><font color="#888888"><span><font color="#888888"><font color="#cc0000" face="georgia, serif" style="font-size:small"><b>Mike Templeman<br></b></font><div style="font-family:arial;font-size:small">
<b><font face="georgia, serif">Head of Development</font></b><font face="georgia, serif"><br><br></font></div><div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/missdestructo" style="color:rgb(17,85,204)" rel="nofollow" link="external" target="_blank">@talkingfrog1950</a></font></div>
<div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/meshfire" style="color:rgb(17,85,204)" rel="nofollow" link="external" target="_blank">@Meshfire</a></font></div>
</font></span></font></div>
</div><img><br></div></div>
<br><br></div></div></div></div><div><div><div class="gmail_quote"><div class="im"><div><div>On Fri, Dec 13, 2013 at 10:40 AM, Mike Templeman <span dir="ltr"><<a href="http://user/SendEmail.jtp?type=node&node=32089&i=1" rel="nofollow" link="external" target="_blank">[hidden email]</a>></span> wrote:<br>
</div></div></div><blockquote style='border-left:2px solid #CCCCCC;padding:0 1em' style="border-left:2px solid #cccccc;padding:0 1em" class="gmail_quote"><div class="im"><div><div>
<div dir="ltr">Also, from observing the Connections screen on the <span style="color:rgb(85,85,85);font-family:Verdana,sans-serif;font-size:13px;line-height:18px">web UI shows that no flow control has been recently turned on for any of the four current connections (four app servers).</span> </div>
</div></div></div><div class="gmail_extra"><div class="im"><div><div><div><br clear="all"><div><div dir="ltr"><div><span><font color="#888888">-- <br></font></span><div dir="ltr"><font color="#888888"><span><font color="#888888"><font color="#cc0000" face="georgia, serif" style="font-size:small"><b>Mike Templeman<br>
</b></font><div style="font-family:arial;font-size:small"><b><font face="georgia, serif">Head of Development</font></b><font face="georgia, serif"><br><br></font></div><div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/missdestructo" style="color:rgb(17,85,204)" rel="nofollow" link="external" target="_blank">@talkingfrog1950</a></font></div>
<div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/meshfire" style="color:rgb(17,85,204)" rel="nofollow" link="external" target="_blank">@Meshfire</a></font></div>
</font></span></font></div>
</div><img><br></div></div>
<br><br></div></div></div></div><div><div><div class="gmail_quote"><div><div class="h5"><div><div>On Fri, Dec 13, 2013 at 10:17 AM, Mike Templeman <span dir="ltr"><<a href="http://user/SendEmail.jtp?type=node&node=32089&i=2" rel="nofollow" link="external" target="_blank">[hidden email]</a>></span> wrote:<br>
</div></div></div></div><blockquote style='border-left:2px solid #CCCCCC;padding:0 1em' style="border-left:2px solid #cccccc;padding:0 1em" class="gmail_quote"><div><div class="h5"><div><div>
<div dir="ltr">Hi Alvaro<div><br></div><div>I would be more than happy to provide logs. But all they have in them is connection and shutdown information. Nothing more. I have just enabled tracing on the vhost and will send the logs shortly. We encounter this issue when under load every day now.</div>
<div><br></div><div>Let me tell you our architecture and deployment:</div><div><br></div><div>rabbitMQ:</div><div><ul><li>m1.large ec2 instance. Version: <span style="color:rgb(68,68,68);font-family:Verdana,sans-serif;font-size:12px;text-align:right">RabbitMQ 3.1.5, </span><span style="color:rgb(68,68,68);font-family:Verdana,sans-serif;font-size:12px;text-align:right"> </span><acronym title="Erlang R14B04 (erts-5.8.5) [source] [64-bit] [smp:2:2] [rq:2] [async-threads:30] [kernel-poll:true]" style="color:inherit;font-family:Verdana,sans-serif;font-size:12px;text-align:right;background-image:none;padding:0px;border-top-left-radius:2px;border-top-right-radius:2px;border-bottom-right-radius:2px;border-bottom-left-radius:2px;border-style:none none dotted;border-bottom-width:1px">Erlang R14B04</acronym><br>
</li><li><span style="color:inherit;font-family:Verdana,sans-serif;font-size:12px;text-align:right">23 queues (transaction and direct)</span><br></li><li>3 exchanges used, two fanout and one topic exchange<br></li><li>topic exchange<br>
</li><li>Topic exchange overview is attached.<br></li><li>46 total channels.<br></li></ul></div><div><br></div><div>AppServers</div><div><ul><li>m1.large tomcat servers running grails application<br></li><li>2-7 servers at any one time.<br>
</li><li>Consume + publish<br></li><li>On busy queues, each server has 16 consumers with prefetch at 100</li><li>message sizes on busy queues are ~4KB.</li><li>publishing rates on busiest queue ranges from 16/s to >100/s. (We need to be able to support 1000/s).</li>
</ul></div><div><br></div><div><acronym title="Erlang R14B04 (erts-5.8.5) [source] [64-bit] [smp:2:2] [rq:2] [async-threads:30] [kernel-poll:true]" style="color:inherit;font-family:Verdana,sans-serif;font-size:12px;text-align:right;background-image:none;padding:0px;border-top-left-radius:2px;border-top-right-radius:2px;border-bottom-right-radius:2px;border-bottom-left-radius:2px;border-style:none none dotted;border-bottom-width:1px">Each AppServer connects to a sharded mongodb cluster of 3 shards. Our first suspicion was that something in Mongo or AWS was causing the periodic delay but AWS techs looked into our volume use and said we were only use 25% of available bandwidth.</acronym></div>
<div><acronym title="Erlang R14B04 (erts-5.8.5) [source] [64-bit] [smp:2:2] [rq:2] [async-threads:30] [kernel-poll:true]" style="color:inherit;font-family:Verdana,sans-serif;font-size:12px;text-align:right;background-image:none;padding:0px;border-top-left-radius:2px;border-top-right-radius:2px;border-bottom-right-radius:2px;border-bottom-left-radius:2px;border-style:none none dotted;border-bottom-width:1px"><br>
</acronym></div><div style="text-align:left"><font face="Verdana, sans-serif"><span style="font-size:12px">At this moment, we have a modest publish rate (~50-60/s) but a backlog of 50,000 messages for the queue "user". You can see a 10 minute snapshot of the queue and see the cycling.</span></font></div>
<div style="text-align:left"><br></div><div style="text-align:left"><font face="Verdana, sans-serif"><span style="font-size:12px">I turned on tracing but the results don't seem to becoming into the log. Is there another way to enable reporting of flow control?</span></font></div>
<span><font color="#888888">
<div style="text-align:left"><font face="Verdana, sans-serif"><span style="font-size:12px"><br></span></font></div><div style="text-align:left"><font face="Verdana, sans-serif"><span style="font-size:12px">Mike Templeman</span></font></div>
<div style="text-align:left"><font face="Verdana, sans-serif"><span style="font-size:12px"><br></span></font></div></font></span></div></div></div></div></div><div class="gmail_extra"><div><div class="h5"><div><div><span><font color="#888888"><br clear="all">
<div>
<div dir="ltr"><div><span><font color="#888888">-- <br>
</font></span><div dir="ltr"><font color="#888888"><span><font color="#888888"><font color="#cc0000" face="georgia, serif" style="font-size:small"><b>Mike Templeman<br></b></font><div style="font-family:arial;font-size:small">
<b><font face="georgia, serif">Head of Development</font></b><font face="georgia, serif"><br><br></font></div><div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/missdestructo" style="color:rgb(17,85,204)" rel="nofollow" link="external" target="_blank">@talkingfrog1950</a></font></div>
<div style="font-family:arial;font-size:small"><font color="#cc0000" face="georgia, serif">T: <a href="http://twitter.com/meshfire" style="color:rgb(17,85,204)" rel="nofollow" link="external" target="_blank">@Meshfire</a></font></div>
</font></span></font></div>
</div><img><br></div></div></font></span></div></div></div></div><div><div class="h5"><div><div>
<br><br><div class="gmail_quote"><div><div>On Fri, Dec 13, 2013 at 6:03 AM, Alvaro Videla-2 [via RabbitMQ] <span dir="ltr"><<a href="http://user/SendEmail.jtp?type=node&node=32089&i=3" rel="nofollow" link="external" target="_blank">[hidden email]</a>></span> wrote:<br>
</div></div><blockquote style='border-left:2px solid #CCCCCC;padding:0 1em' style="border-left:2px solid #cccccc;padding:0 1em" class="gmail_quote"><div>
Mike,
<br><br>Would you be able to provide information more information to help us
<br>debug the problem?
<br><br>Tim (from the rabbitmq team) requested more info in order to try to
<br>find answers for this.
<br><br>For example, when consumption drops to zero, are there any logs on the
<br>rabbitmq server that might tell of a flow control mechanism being
<br>activated?
<br><br>Regards,
<br><br>Alvaro
<br><br><br></div><div>On Fri, Dec 13, 2013 at 2:19 AM, MikeTempleman <<a href="http://user/SendEmail.jtp?type=node&node=32063&i=0" rel="nofollow" link="external" target="_blank">[hidden email]</a>> wrote:
</div><div><div><div><div><div class='shrinkable-quote'><br>> Tyson
<br>>
<br>> Did you ever find an answer to this question? We are encountering virtually
<br>> the exact same problem.
<br>>
<br>> We have a variable number of servers setup as producers and consumers and
<br>> see our throughput drop to zero on a periodic basis. This is most severe
<br>> when there are a few hundred thousand messages on rabbit.
<br>>
<br>> Did you just drop Rabbit? Ours is running on an m1.large instance with RAID0
<br>> ephemeral drives, so size and performance of the disk subsystem is not an
<br>> issue (we are still in beta). We have spent untold hours tuning our sharded
<br>> mongodb subsystem only to find out that it is only being 25% utilized (at
<br>> least it will be blazing fast if we ever figure this out).
<br>>
<br>>
<br>>
<br>>
<br>>
<br>> --
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