or-tools-ruby-stack-level-too-deep

This app demos a problem I'm currently having when running code using the or-tools gem in a web server on my local machine (a MacBook Air with an M1). The problem I'm having is that it errors out with stack level too deep when it runs the solver.solve gem code. The stack trace only contains information about what code called this code, not anything about what happens inside solver.solve.

$ ruby run_in_web_server.rb

... server starts ...
... I visit localhost:4567 ...

2022-02-07 12:26:26 - SystemStackError - stack level too deep:
        /Users/jonathan.mohrbacher/Code/stack-overflow/lib/demo/solver.rb:142:in `solve'
        /Users/jonathan.mohrbacher/Code/stack-overflow/lib/demo/solver.rb:142:in `run_solver'
        /Users/jonathan.mohrbacher/Code/stack-overflow/lib/demo/solver.rb:43:in `solve'
        /Users/jonathan.mohrbacher/Code/stack-overflow/lib/demo/solver.rb:23:in `solve'
        /Users/jonathan.mohrbacher/Code/stack-overflow/lib/demo.rb:18:in `run'
        run_in_web_server.rb:10:in `block in <main>'
        ... sinatra-specific stack trace ...

However, when I run this code in the terminal, I don't have this problem. And when I run this code in docker, I don't have this problem. So my hunch is that on Macs with M1 chips, there's something wrong with either the or-tools gem or the underlying or-tools binary.

Install it locally on a Mac

To install this app locally on a mac, you first need Homebrew and rbenv setup on your machine.

• Install ruby 3.1.0 (you may already have it installed).

  rbenv install -s $(cat .ruby-version)
  gem update --system
  gem install bundler
  rbenv rehash

• Install or-tools.

  brew install or-tools

• Tell bundle where to find your installation of or-tools.

  bundle config build.or-tools --with-or-tools-dir=/opt/homebrew

• Install the gems.

  bundle

Run it locally on a Mac

• Run the app one time in the terminal and exit.

  ruby run_in_terminal.rb

• Run the web server.

  ruby run_in_web_server.rb

  • View it at http://localhost:4567
  • On my machine, this is where I hit the stack level too deep error!

Install it with docker

• Build the image.

  docker-compose build

Run it with docker

• Run the app one time in the terminal and exit.

  docker-compose run --rm app ruby run_in_terminal.rb

• Run the web server.

  docker-compose run --rm --service-ports app ruby run_in_web_server.rb

  • View it at http://localhost:4567
• Drop into the container.

  docker-compose run --rm --service-ports app bash

Debug

• Documentation for debug.gem is here.
• Set a breakpoint with require 'debug'; binding.break.
• Show where you are with list and list -.
• Continue with continue.
• Quit and kill the program with kill!.
• More control flow options are documented here.