clearing active connections in the ConnectionManagement middleware if an exception happens

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -446,6 +446,9 @@ module ActiveRecord
         status, headers, body = @app.call(env)
 
         [status, headers, Proxy.new(body, env.key?('rack.test'))]
+      rescue
+        ActiveRecord::Base.clear_active_connections!
+        raise
       end
     end
   end

activerecord/test/cases/connection_management_test.rb

@@ -57,6 +57,13 @@ module ActiveRecord
         assert ActiveRecord::Base.connection_handler.active_connections?
       end
 
+      def test_connections_closed_if_exception
+        app       = Class.new(App) { def call(env); raise; end }.new
+        explosive = ConnectionManagement.new(app)
+        assert_raises(RuntimeError) { explosive.call(@env) }
+        assert !ActiveRecord::Base.connection_handler.active_connections?
+      end
+
       test "doesn't clear active connections when running in a test case" do
         @env['rack.test'] = true
         @management.call(@env)