`synchronize': can't be called from trap context (ThreadError)

[aaronjensen]

Steps to reproduce

I reported this to guard/listen#565 as well, in case the fix needs to be there.

Use:

  config.file_watcher = ActiveSupport::EventedFileUpdateChecker

And puma as your web server. The warning happens randomly, but when it does you will see:

my-app/gems/ruby/3.1.0/gems/actionview-7.0.4/lib/action_view/helpers/tag_helper.rb:189: warning: Exception in finalizer #<Proc:0x000000010852fb80 my-app/gems/ruby/3.1.0/gems/activesupport-7.0.4/lib/active_support/evented_file_update_checker.rb:91>
my-app/gems/ruby/3.1.0/gems/listen-3.7.1/lib/listen/fsm.rb:80:in `synchronize': can't be called from trap context (ThreadError)
        from my-app/gems/ruby/3.1.0/gems/listen-3.7.1/lib/listen/fsm.rb:80:in `transition!'
        from my-app/gems/ruby/3.1.0/gems/listen-3.7.1/lib/listen/fsm.rb:104:in `transition_with_callbacks!'
        from my-app/gems/ruby/3.1.0/gems/listen-3.7.1/lib/listen/fsm.rb:72:in `transition'
        from my-app/gems/ruby/3.1.0/gems/listen-3.7.1/lib/listen/listener.rb:103:in `stop'
        from my-app/gems/ruby/3.1.0/gems/activesupport-7.0.4/lib/active_support/evented_file_update_checker.rb:111:in `stop'
        from my-app/gems/ruby/3.1.0/gems/activesupport-7.0.4/lib/active_support/evented_file_update_checker.rb:92:in `block in finalizer'
       ... additional unrelated application stacktrace ...

It appears to be action_view/cache_expiry that is being finalized (the below is the caller of initialize that I store to print again in the finalizer.

my-app/gems/ruby/3.1.0/gems/activesupport-7.0.4/lib/active_support/evented_file_update_checker.rb:45:in `new'
my-app/gems/ruby/3.1.0/gems/activesupport-7.0.4/lib/active_support/evented_file_update_checker.rb:45:in `initialize'
my-app/gems/ruby/3.1.0/gems/actionview-7.0.4/lib/action_view/cache_expiry.rb:48:in `new'
my-app/gems/ruby/3.1.0/gems/actionview-7.0.4/lib/action_view/cache_expiry.rb:48:in `block in execute_if_updated'
my-app/gems/ruby/3.1.0/gems/actionview-7.0.4/lib/action_view/cache_expiry.rb:42:in `synchronize'
my-app/gems/ruby/3.1.0/gems/actionview-7.0.4/lib/action_view/cache_expiry.rb:42:in `execute_if_updated'
my-app/gems/ruby/3.1.0/gems/actionview-7.0.4/lib/action_view/cache_expiry.rb:15:in `block in run'
my-app/gems/ruby/3.1.0/gems/activesupport-7.0.4/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
my-app/gems/ruby/3.1.0/gems/activesupport-7.0.4/lib/active_support/dependencies/interlock.rb:41:in `permit_concurrent_loads'
my-app/gems/ruby/3.1.0/gems/actionview-7.0.4/lib/action_view/cache_expiry.rb:14:in `run'
my-app/gems/ruby/3.1.0/gems/activesupport-7.0.4/lib/active_support/execution_wrapper.rb:29:in `before'

Expected behavior

No warning, it seems like stopping listen in a finalizer is error prone because those may run in traps.

Actual behavior

The warning

System configuration

Rails version: 7.0.4

Ruby version: 3.1.2

[rails-bot]

This issue has been automatically marked as stale because it has not been commented on for at least three months.
The resources of the Rails team are limited, and so we are asking for your help.
If you can still reproduce this error on the 7-0-stable branch or on main, please reply with all of the information you have about it in order to keep the issue open.
Thank you for all your contributions.

[ksweetie]

I'm seeing the same error using Rails/Puma/ViewComponent/Listen:

/Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/activesupport-7.0.4.3/lib/active_support/ordered_options.rb:44: warning: Exception in finalizer #<Proc:0x0000000135bee3e0 /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/activesupport-7.0.4.3/lib/active_support/evented_file_update_checker.rb:91>
/Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/listen-3.8.0/lib/listen/fsm.rb:80:in `synchronize': can't be called from trap context (ThreadError)
	from /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/listen-3.8.0/lib/listen/fsm.rb:80:in `transition!'
	from /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/listen-3.8.0/lib/listen/fsm.rb:104:in `transition_with_callbacks!'
	from /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/listen-3.8.0/lib/listen/fsm.rb:72:in `transition'
	from /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/listen-3.8.0/lib/listen/listener.rb:103:in `stop'
	from /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/activesupport-7.0.4.3/lib/active_support/evented_file_update_checker.rb:111:in `stop'
	from /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/activesupport-7.0.4.3/lib/active_support/evented_file_update_checker.rb:92:in `block in finalizer'
	from /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/activesupport-7.0.4.3/lib/active_support/ordered_options.rb:44:in `to_s'
	from /Users/kevinsweet/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/activesupport-7.0.4.3/lib/active_support/ordered_options.rb:44:in `method_missing'

@aaronjensen Did you happen to find a fix/workaround?

[aaronjensen]

@ksweetie I tested w/ main and didn't see it. Could you try that and see if it fixes it for you?

[rails-bot]

This issue has been automatically closed because there has been no follow-up response from the original author. We currently don't have enough information in order to take action. Please reach out if you have any additional information that will help us move this issue forward.