Bug #20167: Code execution isn't recorded in Ractor

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: 3.3.0
• Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN

[shia (Sangyong Sim)]

reproduction code

# frozen-string-literal: true

require "coverage"

Coverage.start

require_relative "./some_lib"
# # some_lib.rb
# class C
#   def hoge(i)
#     i
#   end
# end

r = Ractor.new do
  loop do
    v = Ractor.receive
    ret_v = C.new.hoge(v)

    Ractor.yield ret_v
  end
end

2.times do |i|
  r << i
  r.take
end

Coverage.result.each do |file, lines|
  if file.include?("some_ractor_lib")
    if lines == [1, 1, 2, nil, nil]
      puts "OK"
    else
      puts "expected: [1, 1, 2, nil, nil]"
      puts "actual: #{lines.inspect}"
    end
  end
end

Target ruby version

3.2.0+ affected

[mame (Yusuke Endoh)]

At this time, the coverage library should be able to only measure coverage for Ractor that invoked Coverage.start. (I have not tried but invoking Coverage.start in multiple Ractors may cause fatal problems.)

To improve this situation, probabily we need the following big modification.

• Covearge.start registers hooks to all existing Ractors.
• The hook measures coverage data per Ractor, not globally.
• Coverage.result aggregates all coverage data from every Ractor.

[jeremyevans0 (Jeremy Evans)]

• Is duplicate of Bug #20158: Ractor affects Coverage results added