A few weeks ago the company I work with noticed a weird problem with its CDN (Content Delivery Network) provider. They noticed that HEAD requests were being responded to by the CDN edge nodes using objects in the cache which had already expired. Whats worse is that even after an explicit content expiry notification was sent, the HEAD responses were still wrong. Long story short, the CDN provider had to setup bypass rules for the HEAD requests so that it always bypasses the cache. There was a slight performance overhead with this, but the workaround solved the problem. Now while this was going on, one of the guys at the CDN support helping us mentioned something about Etags and why we should be using it. I didn't understand how Etags would solve the problem if the CDN itself had a bug which was ignoring expiry information, but I said I'll investigate. Anyway, the traditional way of communicating object expiry is using the Last-Modified timestamp. ETags is another way of doing t
Showing posts from August 12, 2007
- Other Apps
There is a very interesting interview with Markus Frind , the one man army behind the website PlentyOfFish.com . The site boasts of traffic higher than match.com, about 30 million page views a day, and runs on a single webserver with a couple of database servers. Markus has found interesting ways of surviving different kinds of problems he had. Here is the direct link to interview in wmv format.
- Other Apps
The code leaked during a facebook bug was posted online by an anonymous user. Though the source itself didn't look very damaging, it did damage the brand "facebook". But I won't go into that in this post, and instead I would like to discus the facebook internals here which alex.moskalyuk touched upon. Alex pointed out that this is not the only code from facebook we have seen. Infact we already know a lot more about how facebook works internally than what most of us would find from the source code to the index.php published yesterday. PHP - This is no surprise. Though PHP is not developed at faceboook, Alex points out that facebook developers are involved atleast at some level in the development of the php. Apache - Neither should this be Mysql - Same here.. Valgrind - This is a suite of tools for debugging and profiling Linux programs. With the tools that come with Valgrind, you can automatically detect many memory management and threading bugs, avoiding h