Hand off the interlock to the new thread in AC::Live

Most importantly, the original request thread must yield its share lock
while waiting for the live thread to commit -- otherwise a request's
base and live threads can deadlock against each other.

1 files changed, 6 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/dependencies/interlock.rb b/activesupport/lib/active_support/dependencies/interlock.rb
index b6a1b25eee..47bcecbb35 100644
--- a/activesupport/lib/active_support/dependencies/interlock.rb
+++ b/activesupport/lib/active_support/dependencies/interlock.rb
@@ -42,6 +42,12 @@ module ActiveSupport #:nodoc:
           yield
         end
       end
+
+      def permit_concurrent_loads
+        @lock.yield_shares(compatible: [:load]) do
+          yield
+        end
+      end
     end
   end
 end