Ruby

Avoid checking interrupt when loading iseq

The interrupt check will unintentionally release the VM lock when loading an iseq.
And this will cause issues with the debug gem's
ObjectSpace.each_iseq method,
which wraps iseqs with a wrapper and exposes their internal states when they're actually not ready to be used.

And when that happens, errors like this would occur and kill the debug gem's thread:

 DEBUGGER: ReaderThreadError: uninitialized InstructionSequence
┃ DEBUGGER: Disconnected.
┃ ["/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:247:in `absolute_path'",
┃  "/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:247:in `block in iterate_iseq'",
┃  "/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:246:in `each_iseq'",
...

A way to reproduce the issue is to satisfy these conditions at the same time:

1. debug gem calling ObjectSpace.each_iseq (e.g. activating a LineBreakpoint).
2. A large amount of iseq being loaded from another thread (possibly through the bootsnap gem).
3. 1 and 2 iterating through the same iseq(s) at the same time.

Because this issue requires external dependencies and a rather complicated timing setup to reproduce, I wasn't able to write a test case for it.
But here's some pseudo code to help reproduce it:

require "debug/session"

Thread.new do
  100.times do
    ObjectSpace.each_iseq do |iseq|
      iseq.absolute_path
    end
  end
end

sleep 0.1

load_a_bunch_of_iseq
possibly_through_bootsnap

[Bug #19348]

Co-authored-by: Peter Zhu [email protected]