rails-observers
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rails
Slow app boot when trying to observe ActiveRecord::Base
If you observe ActiveRecord::Base in order to do something if any model is changed there is some bug in how the observers lists are created causing the app boot to take a long time when eager loading code.
In our case we had an observer that removed comments if a model was destroyed and it had associated comments.
I've reproduced the issue here: https://github.com/barsoom/reproduce_observer_error
We don't use observers in any apps anymore, but thought I'd post this in case someone else had the same issue.
Just as Google food: in our case, we (I'm on the same team as @joakimk) noticed this as Resque workers taking a long time to boot (several minutes) after upgrading from Rails 3 to Rails 4 and switching to rails-observers.
The list of observed models seems to grow exponentially, containing each model many times (duplicates). It is apparently solved by putting models.uniq! in Observing.observe(*models). I'll try to put a fix together...
@anthonyjsmith Do you consider this issue solved? Just wondering if we can remove https://github.com/barsoom/reproduce_observer_error.
It's been a few years, and I'm not working with Rails any more, so my memory is a bit hazy, but yes, I consider it solved.
... although the pull request seems to still be open, so maybe it isn't fully solved yet...? https://github.com/rails/rails-observers/pull/36
Definitely not resolved yet, it takes us like 20 seconds to load each constant. Stack trace is always in this code:
0: /Users/cjbottaro/.gem/ruby/2.3.3/gems/activesupport-5.1.6/lib/active_support/core_ext/regexp.rb:7:in `match?'
1: /Users/cjbottaro/.gem/ruby/2.3.3/gems/activerecord-5.1.6/lib/active_record/dynamic_matchers.rb:33:in `block in match'
2: /Users/cjbottaro/.gem/ruby/2.3.3/gems/activerecord-5.1.6/lib/active_record/dynamic_matchers.rb:33:in `each'
3: /Users/cjbottaro/.gem/ruby/2.3.3/gems/activerecord-5.1.6/lib/active_record/dynamic_matchers.rb:33:in `find'
4: /Users/cjbottaro/.gem/ruby/2.3.3/gems/activerecord-5.1.6/lib/active_record/dynamic_matchers.rb:33:in `match'
5: /Users/cjbottaro/.gem/ruby/2.3.3/gems/activerecord-5.1.6/lib/active_record/dynamic_matchers.rb:8:in `respond_to_missing?'
6: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:309:in `respond_to?'
7: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:309:in `block in observe'
8: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:309:in `collect!'
9: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:309:in `observe'
10: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:358:in `observed_class_inherited'
11: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:352:in `update'
12: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:147:in `block in notify_observers'
13: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:147:in `each'
14: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:147:in `notify_observers'
15: /Users/cjbottaro/.gem/ruby/2.3.3/gems/rails-observers-0.1.5/lib/rails/observers/active_model/observing.rb:199:in `inherited'
