memory leak in ActiveRecord::Base.scoped_methods

rubyonrails-core
1

Hi All,

I tracked down a memory leak (600~1000kb per request for our setup) originated from this commit,

commit ca6d71753f3a2e8a0a29108b7c55ba3b7c8cd943

    Deprecate allow_concurrency and make it have no effect

It's a commit that deprecated `'allow_concurrency', but looks like it kept all them mechanism intact (which is kinda weird). The patch below stops the leaking, but I don't really know why Thread.current is still in there, or why it's leaking.

It surprised me that it's from so far back.

Howard

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/ active_record/base.rb index a36a137..df31a3d 100755 --- a/activerecord/lib/active_record/base.rb +++ b/activerecord/lib/active_record/base.rb @@ -2023,7 +2023,8 @@ module ActiveRecord #:nodoc:          end

         def scoped_methods #:nodoc: - scoped_methods = (Thread.current[:scoped_methods] ||= {}) + @scoped_methods ||= {} + scoped_methods = @scoped_methods            scoped_methods[self] ||=          end

2

We still need to make sure it is threadsafe. Can you run please your benchmarks against http://gist.github.com/22713

3

We still need to make sure it is threadsafe. Can you run please your benchmarks againsthttp://gist.github.com/22713

cool, that stopped the leaking.

I still don't see how it's leaking though. Would you elaborate?

4

Apparently, the GC does always properly cleanup the values for thread locals. I'd consider a bug in the GC.