From: sin@...
Date: 2021-01-12T10:21:02+00:00
Subject: [ruby-core:102030] [Ruby master Bug#17529] Ractor Segfaults with GC	enabled

Issue #17529 has been updated by prajjwal (Prajjwal Singh).


@ko1

It crashes for any value of ARGV[0] between 1 and 25 (that I tested).

The fact that its happening so consistently for me and not for you makes me wonder if the problem stems from my version of Linux or GCC? Some other compile time option perhaps?

Here's my GCC version:

```
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++,d --with-isl --with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit --enable-cet=auto --enable-checking=release --enable-clocale=gnu --enable-default-pie --enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object --enable-install-libiberty --enable-linker-build-id --enable-lto --enable-multilib --enable-plugin --enable-shared --enable-threads=posix --disable-libssp --disable-libstdcxx-pch --disable-libunwind-exceptions --disable-werror gdc_include_dir=/usr/include/dlang/gdc
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.2.0 (GCC) 
```

And Linux:

```
Linux Wraith 5.9.14-arch1-1 #1 SMP PREEMPT Sat, 12 Dec 2020 14:37:12 +0000 x86_64 GNU/Linux
```

Ruby Configure Args

```
'--prefix=/home/prajjwal/.rbenv/versions/3.0.0' '--enable-shared' 'LDFLAGS=-L/home/prajjwal/.rbenv/versions/3.0.0/lib ' 'CPPFLAGS=-I/home/prajjwal/.rbenv/versions/3.0.0/include '
```

----------------------------------------
Bug #17529: Ractor Segfaults with GC enabled
https://bugs.ruby-lang.org/issues/17529#change-89882

* Author: prajjwal (Prajjwal Singh)
* Status: Open
* Priority: Normal
* ruby -v: 3.0.0
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
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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