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[glance] worker, thread, taskflow interplay



On 8/15/19 2:55 AM, Gregory Orange wrote:
> We are trying to figure out how these two settings interplay in:
> 
> [DEFAULT]/workers
> [taskflow_executor]/max_workers

This depends on the executor being used. There are both thread and 
process executors, so it will either affect the number of threads or 
processes started.

> [oslo_messaging_zmq]/rpc_thread_pool_size

This is a zeromq-specific config opt that has been removed from recent 
versions of oslo.messaging (along with the zeromq driver).

More generally, the thread_pool options in oslo.messaging will affect 
how many threads are created to handle messages. I believe that would be 
per-process, not per-service (but someone correct me if I'm wrong).

> 
> Just setting workers makes a bit of sense, and based on our testing:
> =0 creates one process
> =1 creates 1 plus 1 child
> =n creates 1 plus n children
> 
> Are there green threads (i.e. coroutines, per https://eventlet.net/doc/basic_usage.html) within every process, regardless of the value of workers? Does max_workers affect that?
> 
> We have read some Glance doco, hunted about various bug reports[1] and other discussions online to get some insight, but I think we're not clear on it. Can anyone explain this a bit better to me? This is all in Rocky.
> 
> Thank you,
> Greg.
> 
> 
> [1] https://bugs.launchpad.net/glance/+bug/1748916
>