From: peter@...
Date: 2021-02-16T15:25:21+00:00
Subject: [ruby-core:102543] [Ruby master Bug#17636] Race condition in check_rvalue_consistency_force when using ractors

Issue #17636 has been reported by peterzhu2118 (Peter Zhu).

----------------------------------------
Bug #17636: Race condition in check_rvalue_consistency_force when using ractors
https://bugs.ruby-lang.org/issues/17636

* Author: peterzhu2118 (Peter Zhu)
* Status: Open
* Priority: Normal
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
When `RGENGC_CHECK_MODE` is enabled and we use multiple ractors, there is a race condition in `check_rvalue_consistency_force` that causes an assertion to fail. It happens when a page is created during the call to `is_pointer_to_heap`, which causes the binary search to fail.

# Reproduction

```ruby
NUM_RACTORS = 10

rs = NUM_RACTORS.times.map do |i|
  Ractor.new(i) do |i|
    arr = []
    
    10_000.times do |j|
      arr << "foo.#{i}.#{j}"
    end

    arr
  end
end

arrs = rs.map { |r| r.take }
```
The crash log is attached below in `crash.log`.


---Files--------------------------------
crash.log (20.1 KB)


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