[rabbitmq-discuss] Cluster Memory Usage

Matthias Radestock matthias at rabbitmq.com
Mon Nov 21 22:50:39 GMT 2011


On 21/11/11 22:16, Travis wrote:
> Yes.  We've seen this problem when there are only a few dozen messages
> and when there are hundreds of thousands.
> Basically, it seems like the slave is always taking up 2-5x the amount
> of memory that the master uses.

In my tests the slave uses a bit less memory than the master, which is 
what I would expect in a relatively lightly loaded system when there are 
no connections to the slave node.

> Looking at the two servers, the slave shows that it's beam.smp has
> spent 12 more hours on cpu than the beam.smp on the master.  This
> doesn't make sense to me if the slave is doing less work because it's
> only handling traffic coming from the master.

That's odd indeed. In my test I see the slave getting by with less than 
half the CPU utilisation of the master.

Do you see this memory and CPU pattern - with the slave using more than 
the master - all the time, including shortly after a restart?

I still haven't got a good trail to follow here. One thing to look at is 
the output of 'rabbitmqctl report' when the system is in the "excessive 
memory use" state. Please send us that.



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