[ruby-core:119416] [Ruby master Feature#20750] Allow rb_thread_call_with_gvl to work when thread already has GVL

Issue #20750 has been updated by matz (Yukihiro Matsumoto).


OK, I accept to make `rb_thread_call_with_gvl` to acquire GVL only when needed. @ko1 worried it may encourage bad design pattern, but not allowing `rb_thread_call_with_gvl` with GVL does not improve the situation.
So I accept it, you handle it with care.

Matz.


----------------------------------------
Feature #20750: Allow rb_thread_call_with_gvl to work when thread already has GVL
https://bugs.ruby-lang.org/issues/20750#change-110030

* 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)
11649-lenent-rb_thread_call_with_gvl.patch (1.26 KB)
11649b-additional-changes.patch (2.91 KB)


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