investigating a shibd crash

[Jerry Shipman]

Hello,

It looks like shibd stopped on one of our SP websites, resulting in some "ListenerException/unable to connect" type stuff. We're trying to figure out what might have happened.

The sysadmin found these in the log from about the right time:

2021-11-04 08:00:48 ERROR Shibboleth.Listener [2208]: failed socket call (unknown), result (22): Invalid argument 
2021-11-04 08:00:48 ERROR Shibboleth.Listener [2208]: select() on incoming request socket (1215) returned error

(These don't immediately mean much to me, I guess I could go dig out my Stevens...)
Do you think those could represent a shibd crash of some kind? Can you guess at what might have caused it, and/or how we might avoid it in the future?

If this is a "normal error" that wouldn't represent a daemon crash, then we can keep digging, i don't know if there might be some other clues in there that we didn't find yet.

There may have been higher-than-usual load on the server at the time it crashed, we have some event going on. But we've done load-testing previously and hadn't run into this, so I don't know if that is related or not.

Thank you for your help,
Jerry