swift-proxy-server sends sequential notification to ceilometer

In gathering notification of swift object upload by linking with ceilometer, 2 objects were uploaded in parallel to Swift. It was observed that even though the objects were uploaded in parallel, the notifications were generated sequentially due to which ceilometer-notification-agent also received them sequentially. This was confirmed by ceilometer sample-list command which showed that the timestamp of the two operations were same. It may lead to the problem wherein details of the second notification will not be visible, since sample-list command is executed between the two already issued notifications. This behavior is because swift-proxy-server sends the 2nd notifications to the RabbitMQ approximately 1 sec after sending the 1st request.