Thanks!<br><br><div class="gmail_quote">On Wed, Mar 28, 2012 at 2:48 PM, Emile Joubert <span dir="ltr"><<a href="mailto:emile@rabbitmq.com">emile@rabbitmq.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi,<br>
<div class="im"><br>
On 28/03/12 13:05, stone wrote:<br>
> One more question, what could possibly be impacted if the default<br>
> heartbeat value is set to 2, 3 or 5 etc. ?<br>
<br>
</div>There is a trade-off. More frequent heartbeats incur greater network and<br>
CPU overhead but detect network conditions earlier. Lower frequencies<br>
incur less overhead but are slower to detect network problems. You<br>
should set the value appropriately for you environment.<br>
<br>
<br>
In answer to your previous question, some reasons for the current<br>
default have come to light. In previous versions of RabbitMQ (before<br>
v1.7.0) the heartbeat was set to a non-zero value and this caused these<br>
problems:<br>
<br>
On busy machines the heartbeats would not be generated quickly enough<br>
and this lead to dropped connections and poor performance.<br>
<br>
One machines with thousands of connections the effort of generating<br>
heartbeats would consume all the CPU resources.<br>
<br>
On brokers that have no activity the heartbeats would prevent paging to<br>
disk and even Erlang hibernation.<br>
<span class="HOEnZb"><font color="#888888"><br>
<br>
<br>
-Emile<br>
<br>
<br>
</font></span></blockquote></div><br>