2 files changed, 22 insertions, 6 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 8ce28eae62..5d8546916e 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -582,6 +582,24 @@ module ActiveRecord
         @available.num_waiting
       end
 
+      # Return connection pool's usage statistic
+      # Example:
+      #
+      #    ActiveRecord::Base.connection_pool.stat # => { size: 15, connections: 1, busy: 1, dead: 0, idle: 0, waiting: 0, checkout_timeout: 5 }
+      def stat
+        synchronize do
+          {
+            size: size,
+            connections: @connections.size,
+            busy: @connections.count { |c| c.in_use? && c.owner.alive? },
+            dead: @connections.count { |c| c.in_use? && !c.owner.alive? },
+            idle: @connections.count { |c| !c.in_use? },
+            waiting: num_waiting_in_queue,
+            checkout_timeout: checkout_timeout
+          }
+        end
+      end
+
       private
         #--
         # this is unfortunately not concurrent
diff --git a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
index a3e2c913c5..45e400b75b 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
@@ -14,12 +14,10 @@ module ActiveRecord
       config[:username] = "root" if config[:username].nil?
       config[:flags] ||= 0
 
-      if Mysql2::Client.const_defined? :FOUND_ROWS
-        if config[:flags].kind_of? Array
-          config[:flags].push "FOUND_ROWS".freeze
-        else
-          config[:flags] |= Mysql2::Client::FOUND_ROWS
-        end
+      if config[:flags].kind_of? Array
+        config[:flags].push "FOUND_ROWS".freeze
+      else
+        config[:flags] |= Mysql2::Client::FOUND_ROWS
       end
 
       client = Mysql2::Client.new(config)