Reduce locking by taking ownership of stale connections

This way, we aren't racing other threads, so we don't need to re-check
the conditional. And we no longer need to hold the lock while calling
remove (which can choose to make a new connection while we wait).

1 files changed, 8 insertions, 9 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
index 51bbc02b0c..98cf97910e 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -556,19 +556,18 @@ module ActiveRecord
         stale_connections = synchronize do
           @connections.select do |conn|
             conn.in_use? && !conn.owner.alive?
+          end.each do |conn|
+            conn.expire
+            conn.lease
           end
         end
 
         stale_connections.each do |conn|
-          synchronize do
-            next unless conn.in_use? && !conn.owner.alive?
-
-            if conn.active?
-              conn.reset!
-              checkin conn
-            else
-              remove conn
-            end
+          if conn.active?
+            conn.reset!
+            checkin conn
+          else
+            remove conn
           end
         end
       end