Avoid catching all Exceptions in load_model

[rpeng]

Would it be possible to change this to allow certain exceptions to re-raise?

mongoid/lib/rails/mongoid.rb

Line 50 in 94fdc7d

rescue Exception => e

Many rails apps pre-load mongo models, and a lot use Zeitwerk to perform the loading. Sometimes, applications will receive SIGTERMs or SIGINTs on startup, and if mongoid happens to be preloading models, this exception would be caught and ignored. This essentially swallows the signal and allows the application to continue booting, even though the framework is in an inconsistent state (e.g. half way through pre-loading).

This also can explain why certain rails users are seeing NameErrors / uninitialized constants / Zeitwerk load errors.

An example would be like so:

    def load_model(file)
      begin
        require_dependency(file)
      rescue SignalException => e
        Logger.new(STDERR).warn("Received signal #{e.message}, raising")
        raise
      rescue Exception => e
        Logger.new(STDERR).warn(e.message)
      end
    end

[edmund-huber]

https://thoughtbot.com/blog/rescue-standarderror-not-exception

I think mongoid should have a really good reason to be rescuing Exception instead of StandardError, what was the original rationale for catching Exception if any?

[alexbevi]

Thanks for the report @rpeng and comment @edmund-huber. I've opened MONGOID-5463 for our team to triage this issue. Once this has been reviewed further updates will be shared via Jira.