High CPU usage by beam.smp

Magnus Kessler mkessler at basho.com
Thu Jan 28 05:23:10 EST 2016


On 28 January 2016 at 09:05, Fasil K <fasil at gnisir.com> wrote:

>
> Hello, I am using riak 2.1.1 for saving some datas (50000 datas).
> I am running riak with a single node so far. my problem is riak is
> consuming almost 40% of CPU in idle state. Can any one help me to solve
> this issue.?
>
>
> With Regards,
>
> Fasil K
>


Hi Fasil,

The CPU usage you observe is due to the way Erlang schedulers work. When
they run out of work, they don't go to sleep immediately, but perform a
busy wait for some time instead. This increases responsiveness. For a nice,
detailed discussion of this please see
http://jlouisramblings.blogspot.co.uk/2013/01/how-erlang-does-scheduling.html

On a single node with the default ring size of 64, you also have a lot more
VNodes than on a typical production node. A VNode is handled by an Erlang
process, and all these processes require their own share of CPU and memory.

I hope this answers your question.

Regards,

Magnus

-- 
Magnus Kessler
Client Services Engineer
Basho Technologies Limited

Registered Office - 8 Lincoln’s Inn Fields London WC2A 3BP Reg 07970431
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