[ruby-core:119254] [Ruby master Feature#20750] Expose ruby_thread_has_gvl_p in ruby/thread.h

["Eregon (Benoit Daloze) via ruby-core" <ruby-core@ml.ruby-lang.org>]

Issue #20750 has been updated by Eregon (Benoit Daloze).


OK the issue/bug is
https://github.com/ruby/ruby/blob/4797b0704ae49fb42c8ad9a45028efbe2298b5f5/thread.c#L1899
```
    if (brb == 0) {
        rb_bug("rb_thread_call_with_gvl: called by a thread which has GVL.");
    }
```
@ko1 I think that's a bug, I think rb_thread_call_with_gvl() should be allowed if the GVL is already acquired, there seems to be no value to prevent it.
TruffleRuby already implements those semantics BTW.
How do you want to solve this issue?

----------------------------------------
Feature #20750: Expose ruby_thread_has_gvl_p in ruby/thread.h
https://bugs.ruby-lang.org/issues/20750#change-109834

* Author: kbrock (Keenan Brock)
* Status: Open
----------------------------------------
Hello All,

I'm hoping we can make `ruby_thread_has_gvl_p` a public method and no longer experimental.

I saw the following code in a gem that was not compiling with ruby 3.3:

``` c
// int ruby_thread_has_gvl_p(void); // <== line of concern
  if (ruby_thread_has_gvl_p()) {
    method_call(&context);
  }
  else {
    rb_thread_call_with_gvl(method_call, &context);
  }
```

400 unique projects on github added the line listed above to fix compilation. [1]

Some of the projects detected the method first in `extconf.rb`, but a majority just referenced it.
`ffi` used to have the detection code but dropped it since the method was in all supported ruby versions.


It feels like this method is now part of the undocumented public interface.
My suggestion is to add the method to the real public interface in `ruby/thread.h`.

PR with possible solution: https://github.com/ruby/ruby/pull/11619
Also included a patch if that is easier

Thank you for your consideration,
Keenan

Timeline:

- Dec 30 2008 - `rb_thread_call_with_gvl` introduced via 9c04a06 [2]
- Jan 12 2009 - `ruby_thread_has_gvl_p` introduced via 6f09fc2 [4]
- Jul 18 2012 - `rb_thread_call_with_gvl` made public via e9a91d2 [3]

Current references to code: `rb_thread_call_with_gvl` [5] `ruby_thread_has_gvl_p` [6]:

[1]: https://github.com/search?q=ruby_thread_has_gvl_p+language%3AC++NOT+is%3Afork++NOT+is%3Aarchived&type=code
[2]: https://github.com/ruby/ruby/commit/9c04a0647fb99f7554cb2e04385ddbb970631e02
[3]: https://github.com/ruby/ruby/commit/e9a91d2c95dfe22ad0487952f7a1053ef9a5fd16
[4]: https://github.com/ruby/ruby/commit/6f09fc2efd1915c4337ce6dded52a8a8771c3222
[5]: https://github.com/ruby/ruby/blob/master/thread.c#L1878
[6]: https://github.com/ruby/ruby/blob/master/thread.c#L1923

---Files--------------------------------
11618.patch (3.18 KB)


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