[ClusterLabs] Resource stop sequence with massive CIB update

[Klaus Wenninger]

On Tue, Aug 13, 2024 at 12:16 AM <alexey at pavlyuts.ru> wrote:

> Hi Ken,
>
> thank you great for your prompt help!
>
> > The second one: --sync-call only waits for the change to be committed to
> the CIB,
> > not for the cluster to respond. For that, call crm_resource --wait
> afterward.
>
> It seems like crm_resource --wait is a very reliable and proven, but
> veeeeery slow approach. I found that even on sustained cluster it takes
> around 2-2.4 seconds for this command returns. When I add it to my script
> flow after resource disable and before deletion, it takes the same time
> about 2-2.2 sec:
>
> 2024-08-12 21:58:14,105 - DEBUG Start applying resource stop changes
> 2024-08-12 21:58:14,126 - DEBUG Start crm_resource --wailt
> 2024-08-12 21:58:16,152 - DEBUG Start applying final changes
> 2024-08-12 21:58:16,173 - INFO     Send request answer
>
> Here it waits 2.26s. The same as sustained call, so I suppose the delay is
> not too much related to cluster state.
>
> But I know that real stop happens within about 100-200 ms unless some
> special conditions happen. The problem is my code works as API server to
> external system, and it is only one small part of job so 2s of waiting is
> not a good for me (((
>
> Is there any way to get a list of unfinished start/stop tasks? Sure, I can
> build the list of resource to be stopped and just check with crm_mon about
> its status unless everyone stopped or error, I can catch resource events
> and watch for every planned stop finished, but it looks simpler and more
> reliable to get active stop task list, if available.
>

Don't know if there is a way to acquire such a list in an (easy) way using
public api.
Basically you might consider making your API asynchronous in that aspect.
Did you explore what alerts might give you? You might get notification
about successful
stops / respectably failed stops more quickly and collect them to be used
either by
the synchronous API or an asynchronous version.

Klaus

>
> Thank you once again!
>
> Sincerely,
>
> Aalex
>
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