NoMethodError (undefined method `paper_trail_enabled_for_model')

[dwbutler]

I'm in using Paper Trail in Rails / ActiveRecord 3.1.15 under JRuby in the Torquebox server. I haven't had any issues until I started load testing. Now, every now and then I see the following error:

NoMethodError (undefined method `paper_trail_enabled_for_model' for #<Class:0x160041f0>)
org/jruby/RubyBasicObject.java:1497:in `method_missing'
/shared/bundle/jruby/1.9/gems/activerecord-3.2.15/lib/active_record/dynamic_matchers.rb:55:in `method_missing'
/shared/bundle/jruby/1.9/gems/activesupport-3.2.15/lib/active_support/core_ext/class/attribute.rb:129:in `paper_trail_enabled_for_model'
/shared/bundle/jruby/1.9/gems/paper_trail-2.7.2/lib/paper_trail/has_paper_trail.rb:175:in `without_versioning'

This is running inside a transaction, when a model is being created, in an after_save callback. All I can imagine is that ActiveSupport's class_attribute is somehow not thread-safe.

Any ideas? Thanks!

[batter]

I've never felt strongly about the need for using class_attribute for a lot of the fields that it is applied to via the has_paper_trail declaration, but can't speak to whether it's thread-safe or not. The one nice thing about class_attribute is that it can be overridden by instances of a class, but somehow I doubt that users really use that functionality. Do we think that cattr_accessor is more thread-safe for some reason? Or perhaps they should just be defined using attr_accessor? I don't have much experience with JRuby.

[dwbutler]

Anything in core Ruby should be thread-safe these days, whether MRI or JRuby. I can't figure out either what is unsafe about class_attribute, but if it's possible to use core Ruby methods that might be a good idea.

[dwbutler]

We just went into production and we're starting to see this error crop up. Should we give cattr_accessor a try?