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 37a9d216df..eb88f191a7 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -128,10 +128,11 @@ module ActiveRecord
         @reserved_connections[current_connection_id] ||= checkout
       end
 
-      # Check to see if there is an active connection in this connection
-      # pool.
+      # Is there an open connection that is being used for the current thread?
       def active_connection?
-        active_connections.any?
+        @reserved_connections.fetch(current_connection_id) {
+          return false
+        }.in_use?
       end
 
       # Signal that the thread is finished with the current connection.
@@ -288,10 +289,6 @@ module ActiveRecord
         end
         c
       end
-
-      def active_connections
-        @connections.find_all { |c| c.in_use? }
-      end
     end
 
     # ConnectionHandler is a collection of ConnectionPool objects. It is used
diff --git a/activerecord/test/cases/connection_pool_test.rb b/activerecord/test/cases/connection_pool_test.rb
index 2c69bfde5b..25375c5f7a 100644
--- a/activerecord/test/cases/connection_pool_test.rb
+++ b/activerecord/test/cases/connection_pool_test.rb
@@ -3,6 +3,8 @@ require "cases/helper"
 module ActiveRecord
   module ConnectionAdapters
     class ConnectionPoolTest < ActiveRecord::TestCase
+      attr_reader :pool
+
       def setup
         super
 
@@ -25,6 +27,39 @@ module ActiveRecord
         @pool.disconnect!
       end
 
+      def active_connections(pool)
+        pool.connections.find_all(&:in_use?)
+      end
+
+      def test_with_connection
+        assert_equal 0, active_connections(pool).size
+
+        main_thread = pool.connection
+        assert_equal 1, active_connections(pool).size
+
+        Thread.new {
+          pool.with_connection do |conn|
+            assert conn
+            assert_equal 2, active_connections(pool).size
+          end
+          assert_equal 1, active_connections(pool).size
+        }.join
+
+        main_thread.close
+        assert_equal 0, active_connections(pool).size
+      end
+
+      def test_active_connection_in_use
+        assert !pool.active_connection?
+        main_thread = pool.connection
+
+        assert pool.active_connection?
+
+        main_thread.close
+
+        assert !pool.active_connection?
+      end
+
       def test_full_pool_exception
         assert_raises(PoolFullError) do
           (@pool.size + 1).times do