<p>What are the avg sizes and the size of a msg that is slow?� Network?� Mtu,nagle?�� Does your NIC have tcp offload?� As a black magic solution ser your system to use deadline schedulerr to see if its worse or better?<br>
jacques</p>
<div class="gmail_quote">On Jul 24, 2012 11:39 AM, "Francesco Mazzoli" <<a href="mailto:francesco@rabbitmq.com">francesco@rabbitmq.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi Brennan,<br>
At Mon, 23 Jul 2012 15:57:24 -0400,<br>
Brennan Sellner wrote:<br>
> The rabbitmq server (v2.8.2) is running on the same machine, so there aren't<br>
> any external networks involved. �We're still running Fedora 11 (kernel 2.6.29,<br>
> Erlang R12B-5.8) for the moment, if that's relevant.<br>
<br>
Please upgrade both RabbitMQ and Erlang if you can (especially rabbit), or<br>
things will be hard to diagnose for us.<br>
<br>
> Time 0.90: The consumer receives and responds to an AMQP heartbeat from<br>
> the server, and acks the delivery of a prior message. �It again drops<br>
> into an amqp_simple_wait_frame.<br>
<br>
That does not sound right, heartbeats require no response.<br>
<br>
> My understanding is that when dealing solely with non-persistent<br>
> messages, Rabbit won't hit the disk until it runs out of RAM. �Is that<br>
> accurate?<br>
<br>
It is accurate, but your understanding of "runs out of RAM" might be misguided:<br>
rabbit will start swapping to disc when the RAM used exceeds `total_ram *<br>
vm_memory_high_watermark', where `vm_high_watermark' is a configurable<br>
application variable, with 0.4 as default:<br>
<a href="http://www.rabbitmq.com/configure.html" target="_blank">http://www.rabbitmq.com/configure.html</a> .<br>
<br>
> Any ideas as to what else might cause this sort of delay, or suggestions on<br>
> how to get further useful information?<br>
<br>
I would say that the most likely thing to be happening is for rabbit to start<br>
paging to disc, so please check that first. �You can monitor your disc space<br>
usage with the rabbitmq management plugin.<br>
<br>
You might also be hitting flow control, but that is related to running out of<br>
RAM. �You can check that as well via the management plugin, the connections will<br>
be marked as "blocked".<br>
<br>
Another option could be that you are running out of file descriptors (maybe you<br>
have a large number of connections open?) and rabbit is blocking until some are<br>
available.<br>
<br>
--<br>
Francesco * Often in error, never in doubt<br>
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</blockquote></div>