Ensure the connection used in a failed rollback is discarded

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

@@ -317,7 +317,12 @@ module ActiveRecord
           end
           raise
         ensure
-          if !error && transaction
+          if transaction
+            if error
+              # @connection still holds an open transaction, so we must not
+              # put it back in the pool for reuse
+              @connection.throw_away! unless transaction.state.rolledback?
+            else
               if Thread.current.status == "aborting"
                 rollback_transaction
               else
@@ -341,6 +346,7 @@ module ActiveRecord
             end
           end
         end
+      end
 
       def open_transactions
         @stack.size

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -501,6 +501,12 @@ module ActiveRecord
         # this should be overridden by concrete adapters
       end
 
+      # Removes the connection from the pool and disconnect it.
+      def throw_away!
+        pool.remove self
+        disconnect!
+      end
+
       # Clear any caching the database adapter may be doing.
       def clear_cache!
         @lock.synchronize { @statements.clear } if @statements

activerecord/test/cases/transactions_test.rb

@@ -30,6 +30,53 @@ class TransactionTest < ActiveRecord::TestCase
     assert_equal title_change, topic.changes["title"]
   end
 
+  if !in_memory_db?
+    def test_rollback_dirty_changes_even_with_raise_during_rollback_removes_from_pool
+      topic = topics(:fifth)
+
+      connection = Topic.connection
+
+      Topic.connection.class_eval do
+        alias :real_exec_rollback_db_transaction :exec_rollback_db_transaction
+        define_method(:exec_rollback_db_transaction) do
+          raise
+        end
+      end
+
+      ActiveRecord::Base.transaction do
+        topic.update(title: "Rails is broken")
+        raise ActiveRecord::Rollback
+      end
+
+      assert_not connection.active?
+      assert_not Topic.connection_pool.connections.include?(connection)
+    end
+
+    def test_rollback_dirty_changes_even_with_raise_during_rollback_doesnt_commit_transaction
+      topic = topics(:fifth)
+
+      Topic.connection.class_eval do
+        alias :real_exec_rollback_db_transaction :exec_rollback_db_transaction
+        define_method(:exec_rollback_db_transaction) do
+          raise
+        end
+      end
+
+      ActiveRecord::Base.transaction do
+        topic.update(title: "Rails is broken")
+        raise ActiveRecord::Rollback
+      end
+
+      topic.reload
+
+      ActiveRecord::Base.transaction do
+        topic.update(content: "Ruby on Rails - modified")
+      end
+
+      assert_equal "The Fifth Topic of the day", topic.reload.title
+    end
+  end
+
   def test_rollback_dirty_changes_multiple_saves
     topic = topics(:fifth)