Bug #19375: File objects are currently shareable, as are other extension objects that shouldn't be.

• Status: Open
• Priority: Normal
• Assignee: -
• Target version: -
• Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

[luke-gru (Luke Gruber)]

I don't know the internals of file.c but I don't think files are thread-safe.

[luke-gru (Luke Gruber)]

• Subject changed from File objects are currently shareable to File objects are currently shareable, as are other extension objects that shouldn't be.

The issue is with Ractor.make_shareable

The same issue occurs with Dir, Tempfile, IO objects, the ENV hash. StringIO and CSV have this problem too. Sockets I think have the issue.

For example, the issue with StringIO is that it needs an initialize_clone method that dup's the string. The underlying issue, though, is that it's a TypedData and doesn't
store its internals in instance variables to be checked by the sharing logic.

require 'stringio'
str = "string".dup
stringio = StringIO.new(str)

rs = 100.times.map do
  Ractor.new do
    strio = receive
    p strio.string.object_id
    p strio.string.frozen?
  end
end
p stringio.string.object_id
rs.each do |r|
  r.send(stringio)
end
rs.each(&:take)