From: "nagachika (Tomoyuki Chikanaga)" <noreply@...>
Date: 2022-03-21T07:53:54+00:00
Subject: [ruby-core:107998] [Ruby master Bug#17529] Ractor Segfaults with GC enabled

Issue #17529 has been updated by nagachika (Tomoyuki Chikanaga).

Backport changed from 2.6: DONTNEED, 2.7: DONTNEED, 3.0: REQUIRED to 2.6: DONTNEED, 2.7: DONTNEED, 3.0: DONE

ruby_3_0 a72b7b898c69a116d754d599e8bb061761015255 merged revision(s) d0d6227a0da5925acf946a09191f172daf53baf2,fff1edf23ba28267bf57097c269f7fa87530e3fa.

----------------------------------------
Bug #17529: Ractor Segfaults with GC enabled
https://bugs.ruby-lang.org/issues/17529#change-96952

* Author: prajjwal (Prajjwal Singh)
* Status: Assigned
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
* ruby -v: ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-linux]
* Backport: 2.6: DONTNEED, 2.7: DONTNEED, 3.0: DONE
----------------------------------------
I've been benchmarking `Ractor` on my machine with the following naive prime number generator:

```ruby
# frozen_string_literal: true

def prime?(n)
  2.upto(n - 1).none? { |i| n % i == 0 }
end

NUM_WORKERS = ARGV[0].to_i

producer = Ractor.new do
  i = 1000000

  loop { Ractor.yield i; i += 1 }
end

workers = (1..NUM_WORKERS).map do
  Ractor.new producer do |producer|
    while n = producer.take
      Ractor.yield [n, prime?(n)]
    end
  end
end

loop do
  _r, ( number, prime ) = Ractor.select(*workers)

  p number if prime
end
```

The code inevitably segfaults, and it appears to be the garbage collector.

If I stick `GC.disable` in there, the code happily chugs along for several minutes on end without a problem.

---Files--------------------------------
ractor.crash (22.5 KB)


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