Tuesday 11 October 2011

Broken Toys

The keen might have noticed this site has been coming and going for the past fortnight :-(

The cause is yet to be determined - I attempted to log in on Monday and nothing was there - although I could SSH in to a different machine on my home network, the blog server was unpingable. I half-expected it to be smouldering from a particularly brutal DOS attack when I came home, but nothing so spectacular. It was just locked up.

I decided to take the opportunity and use this downtime to do some comprehensive upgrades I'd been wanting to perform for a while:

  • Move the server to Debian to match my other Debian/Ubuntu boxen
  • Upgrade my web platform to the latest-and-greatest Tomcat 7.0.22
  • Upgrade the blog software to Pebble 2.6.2 to get lots of fixes/improvements

Such big plans expose one to potential big failures. And I had a lot of them. Firstly, my wonderful, faithful little NetVista just simply didn't have the grunt to run anything much bigger than a "Hello World" webapp on the shiny new Tomcat/Debian stack - its 256Mb of RAM and puny 233MHz CPU had no chance against the might of a full JEE application like Pebble as well as running a beefcake OS like Debian (as opposed to the super-slender Puppy Linux it had before). So I moved the whole thing to a VM on a much gruntier Ubuntu Server I have. It remains to be seen what will happen to the little IBM - it's not adding much to the party at this point ...

So after migrating to the new hardware, and getting the new Pebble going, I had to bring in the performance improvements I blogged about a while ago, which still don't exist in the official Pebble codebase. (Note to self: must contribute those fixes back!). Initially it seemed all good - my YSlow score of 99 is mighty pleasing - but there was an elephant in the room.

Why the hell was it taking 8.5 seconds to serve up the home page?

Extensive (frustrating) investigation has shown that something added to Pebble since v2.4 has pretty badly borked the performance when hitting /. Fully-specified URLs are fine. I'm suspecting the new-in-2.5 SEO-friendly URL generator, but that's pure speculation. So until the bad interaction between Tomcat 7 and Pebble > 2.4 is sorted out, I'm stuck with icky URLs and no OAuth logins :-(

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