How facebook processing it's comments, mails and sms

This Question is regarding on How the Facebook process an activity.I just want to know how they are doing it so efficiently.

When we Comment on facebook there are series of back ground process such as mailing , smsing to all the subscribers etc. If they are doing all the mailing and smsing,sending notifications etc in a single stretch posting a comment will take so much time. right? So how they are managing this??

For Eg.: when i comment on my friends photo.They will send a notification and mail (if they are subscribed) to all the previous commentators on the same photo and to the owner of the photo. if there is a 50 commentators on the photo they have to send a 50 notifications and mails in that they need to check who all subscribed etc..

if we try to send the 50 notific开发者_JAVA百科ation and mails on submitting the comment.Then it will take too much time to process

How they are achieving this so efficiently.

They are likely posting the message to a queue to be processed quickly but asynchronously so the response can be sent immediately to the user. Then some background process pulls the message from a queue and does all the notification processing.

These may help:

• http://highscalability.com/blog/category/facebook
• http://royal.pingdom.com/2010/06/18/the-software-behind-facebook/
• http://faler.wordpress.com/2009/05/08/best-practices-for-scalable-high-performance-systems/
• http://www.readwriteweb.com/hack/2010/11/facebook-mysql-scale.php
• http://www.readwriteweb.com/archives/update_facebook_rewrites_php_runtime_with_project.php

Facebook documents the Open Source technologies they use. See http://developers.facebook.com/opensource/