From: "hsbt (Hiroshi SHIBATA) via ruby-core" <ruby-core@...>
Date: 2023-01-23T02:14:11+00:00
Subject: [ruby-core:111982] [Ruby master Bug#19338] Ruby hangs when ouputting warnings inside ractor with VM lock held

Issue #19338 has been updated by hsbt (Hiroshi SHIBATA).

Status changed from Open to Assigned
Assignee set to ko1 (Koichi Sasada)

----------------------------------------
Bug #19338: Ruby hangs when ouputting warnings inside ractor with VM lock held
https://bugs.ruby-lang.org/issues/19338#change-101418

* Author: luke-gru (Luke Gruber)
* Status: Assigned
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------

This code causes Ruby to hang:

``` ruby
rs = []
2.times do
  rs << Ractor.new do
    MYCONSTANT = 2
  end
end
rs.each(&:take)
```

There is a problem when the warning is being outputted with multiple ractors. A thread is calling RB_VM_LOCK() while holding the VM lock in ractor.c (ractor_check_blocking())

If the code is changed to RB_VM_LOCK_ENTER() and RB_VM_LOCK_LEAVE() then it fixes it, but I don't know if there's a better way.

Thanks!




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