[OpenSIPS-Users] Autoscaling

[Dan Pascu]

On 25 Apr 2019, at 17:29, Bogdan-Andrei Iancu wrote:

> Hi Dan,
> 
> The load is considered as the time a processes is busy in doing something (instead of waiting for a new task to handle). It is completely unrelated to the CPU load. Also the load will count any busy waiting or I/O waiting done by the process.

In this case is it correct to define load per process as time_spent_processing_per_cycle/measurement_cycle?

Also regarding this measurement cycle, I see a loose reference in the docs mentioning that a cycle is "like 2 seconds". Can the cycle length be defined, and if so how? If it cannot be defined, what is its actual value? (the "like 2 seconds" reference sounds vague).

> 
> Regards,
> 
> Bogdan-Andrei Iancu
> 
> OpenSIPS Founder and Developer
>  https://www.opensips-solutions.com
> OpenSIPS Summit 2019
>  https://www.opensips.org/events/Summit-2019Amsterdam/
> 
> On 04/25/2019 04:47 PM, Dan Pascu wrote:
>> I'm trying to understand how autoscaling works and I'd like some clarifications.
>> 
>> When a process group load is calculated is that based on actual CPU load, or is it just computed as busy_processes/total_processes in that group?
>> 
>> What I'm trying to figure out is the behavior in the case of the TCP process group, which is let's say configured to spawn a new worker when it reaches 70% load for the TCP worker group. Now consider that this group starts with 5 workers and at some point in time, all 5 workers are busy processing a message. In addition let's consider that the DNS lookup is misconfigured and it takes 3 seconds to get an answer. This means that if the proxy receives 5 messages at a time, all 5 workers will be blocked in a synchronous DNS lookup for 3 seconds, but each using 0% CPU.
>> 
>> My question is, in this 3 second time window (when all 5 workers are blocked in waiting for the DNS lookup), if a new request arrives over TCP, will opensips spawn a new TCP worker because all 5 workers are busy and it considers the load to be 100%, or it will do nothing because it uses CPU load which is 0% since all 5 processes are sleeping waiting for the DNS answer?
>> 
>> --
>> Dan
>> 
>> 
>> 
>> 
>> 
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> 


--
Dan