[ruby-core:87873] [Ruby trunk Misc#14901] [PATCH] do not block SIGCHLD in normal Ruby Threads

Issue #14901 has been updated by k0kubun (Takashi Kokubun).


I have not completely read your patch for [Bug #14867] yet, so let me ask some questions to understand the context.

> I blocked SIGCHLD in normal Ruby Threads for [Bug #14867]

In the current trunk, in what kind of situation are normal Ruby Threads "blocked" by SIGCHLD? Are they blocked by default, or only during Process.waitall and its families are invoked?

And also, does the "blocked" mean interruption by a signal handler for SIGCHLD?

> MJIT causes many SIGCHLD signals

So whenever MJIT compiler process is spawned, normal Ruby Threads are blocked for now, right?

> One alternative could be to handle signals with MJIT thread when MJIT is enabled, or to lazy-spawn timer thread to handle
signals when MJIT is enabled (MJIT + gcc requires a lot of resources, anyways).

If you're going to remove the Timer thread from normal Ruby execution, I'm in favor of handling signals with MJIT thread for simplicity, if it's not so hard to implement it in MJIT thread.

At a glance of your attached patch, it doesn't seem to implement either of it but to just give up the current approach. If tests with -DMJIT_FORCE_ENABLE are fine with the patch and problems in "OpenSSL::PKey::*.new" and " test/-ext-/gvl/test_last_thread.rb" are solved by it, go ahead to commit that. But if it's not the case, I wanna see your complete patch just in case.

----------------------------------------
Misc #14901: [PATCH] do not block SIGCHLD in normal Ruby Threads
https://bugs.ruby-lang.org/issues/14901#change-72886

* Author: normalperson (Eric Wong)
* Status: Open
* Priority: Normal
* Assignee: k0kubun (Takashi Kokubun)
----------------------------------------
@k0kubun: any opinions on this?  Thanks.

```
I blocked SIGCHLD in normal Ruby Threads for [Bug #14867]
because I noticed at least two places which could not deal
with spurious wakeups in our test suite.

I also want to get rid of timer-thread due to resource
limitations [ruby-core:87773].  MJIT causes many SIGCHLD signals
so I found the following problems with cppflags=-DMJIT_FORCE_ENABLE=1

* OpenSSL::PKey::*.new does not resume on handle signals.
  rhenium acknowledged the problem and it should be in trunk soon:
  https://bugs.ruby-lang.org/issues/14882

* test/-ext-/gvl/test_last_thread.rb does not handle spurious
  wakeups.  Original report is in Japanese:
  https://bugs.ruby-lang.org/issues/11237
  I don't think it's a realistic expectation for code to be
  unable to deal with spurious wakeups.

One alternative could be to handle signals with MJIT thread
when MJIT is enabled, or to lazy-spawn timer thread to handle
signals when MJIT is enabled (MJIT + gcc requires a lot of
resources, anyways).
```


---Files--------------------------------
0001-do-not-block-SIGCHLD-in-normal-Ruby-Threads.patch (2.5 KB)


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