Ignore the result of pthread_kill in ubf_wakeup_thread

[jeremyevans]

After an upgrade to Ruby 3.3.0, I experienced reproducible production crashes of the form:

[BUG] pthread_kill: No such process (ESRCH)

This is the only pthread_kill call in Ruby. The result of pthread_kill was previously ignored in Ruby 3.2 and below. Checking the result was added in be1bbd5 (MaNy).

I have not yet been able to create a minimal self-contained example, but it should be safe to remove the checks.

[nobu]

No clue by enabling USE_RUBY_DEBUG_LOG?

[kosaki]

LGTM

[jeremyevans]

No clue by enabling USE_RUBY_DEBUG_LOG?

I haven't had a chance to do that. ESRCH means the thread id given is invalid. Maybe it already exited and just needs to be joined, or maybe this an an OpenBSD-specific issue. In discussion with @ko1, he said the result of pthread_kill can be ignored.

[kosaki]

No clue by enabling USE_RUBY_DEBUG_LOG?

I haven't had a chance to do that. ESRCH means the thread id given is invalid. Maybe it already exited and just needs to be joined, or maybe this an an OpenBSD-specific issue. In discussion with @ko1, he said the result of pthread_kill can be ignored.

I don't think this is OpenBSD-specific. But you know, OpenBSD's userland thread scheduler often find some thread timing issue. That's just their intention. I really respect them.