Prevent potentially misleading error message about "no heartbeat"

[okurz]

In the context of
github.com/os-autoinst/openQA
we observed error messages coming from Mojo::Server::Prefork
when otherwise there is no harmful effect observed. As the underlying
prefork module should only inform about a potentially erroneous
situation but can not know about the effect on any component that uses
the prefork module the log message instead should not claim an error but
rather only inform. Hence this commit reduces the log level from error
to info accordingly.

Related progress issue: https://progress.opensuse.org/issues/138536

[guest20]

Is there a reason it's not possible for y'all to extended the timeout it with the attribute "heartbeat_timeout" in Mojo::Server::Prefork since your application requires it?

[okurz]

Is there a reason it's not possible for y'all to extended the timeout it with the attribute "heartbeat_timeout" in Mojo::Server::Prefork since your application requires it?

yes, we already use 900s. As far as I understood the evaluation in https://progress.opensuse.org/issues/106759 and https://progress.opensuse.org/issues/138536 regarding how this is used within the context of github.com/os-autoinst/openQA/ we will run into the timeout regardless. Probably something in the implementation is sub-optimal but anyway I still think the message with a log level of "error" is too strict

[kraih]

Why info over warn?

[okurz]

Why info over warn?

I would say same reasoning because I think this component can not know if the condition is harmful to the caller but if you guys prefer "warn" that would also help us.

[guest20]

Am I misunderstanding what the log message means?

Something blocked the worker for more than the heartbeat timeout and the supervisor has decided to kill that worker, causing anybody with a pending request to that worker to never receive any more bytes in response... Is that the situation this message warns about?