Issue #21096 has been updated by midnight (Sarun R). Subject changed from Ruby hangs up when compiling for bytecode on AArch64 emulated by QEMU to `Process.fork` hangs up on QEMU when called multiple times. Hello, I made progress somehow and the issue has been isolated. Here is the minimal reproduction code without projects, 3rd party gems, or external dependencies apart from MRI on Linux/QEMU. ~~~Ruby $stdout.sync = true pid_list = 4.times.map do Process.fork do puts 'success!' exit!(true) end end pid_list.each do |pid| Process.wait2(pid) end ~~~ On QEMU, you'll get only one `success!` printed and the Ruby interpreter hangs. ---------------------------------------- Bug #21096: `Process.fork` hangs up on QEMU when called multiple times. https://bugs.ruby-lang.org/issues/21096#change-111923 * Author: midnight (Sarun R) * Status: Open * ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Hello, We are experiencing issues when using [Bootsnap](https://github.com/Shopify/bootsnap) for production container image building, specifically when running `bundle exec bootsnap precompile --gemfile` on an emulated ARM64 environment on AMD64 hosts. Here are more details: * Bootsnap is a Ruby gem for bytecode caching, which speeds up loading times. It achieves this by calling `RubyVM::InstructionSequence.compile_file` and `RubyVM::InstructionSequence.load_from_binary`. * When running `bundle exec bootsnap precompile --gemfile` in the environment described (using QEMU to emulate the AArch64 instruction set), the process can compile and generate some bytecode but eventually hangs. * The hang seems random, occurring at different points during the process. * According to [a Rails GitHub issue](https://github.com/rails/rails/issues/54039), the issue affects both `Docker` and `containerd`, as well as native Linux and macOS environments. * From [a Bootsnap GitHub issue](https://github.com/Shopify/bootsnap/issues/495), the problem likely doesn't occur in Ruby `3.2.6` but appears in later versions. * So far, the common factors observed are: * Emulated ARM64 on AMD64 CPUs (likely using QEMU) * Newer Ruby versions (e.g., 3.3 and 3.4) As a user, I don't have the expertise to debug the issue but am willing to gather more information if provided with sufficient instructions. -- https://bugs.ruby-lang.org/