Friday, September 25, 2015

Winning Amaz-ing Hackathon - Meghadūta

Last weekend was fun at Chennai Amazon office. In association with Venture City, Kindle Team at Chennai organized a hackathon on the theme - "Building Scalable Distributed Systems". The name was theme was good enough to attract me to register for the event :) I went there with Salaikumar and Vijay Kumar to the event under the team name - "Salaikumar".

You can find the problem statements given at the hackathon here.

We won two awards at the event - "Best Voted Award" and "Ultimate Hack Award".

You can find our code at

Few pictures taken during the event

Me doing the presentation of our hack

Salai helping me with the screens

Our prize, a Kindle Paper White each and some certificates :)

Saturday, September 12, 2015

Find that missing Host in Hadoop Cluster

I've started to manage 200 node hadoop clusters recently at work. All these are running on AWS with latest CDH5. We went from separate HDFS + TT model to co-locating TT and DN daemons together.

These machines are all Spot machines backed by a ASG (Auto Scaling Group). If any of them die because of spot prices, they would come back up in a while. So to manage these machines better we attach our own custom generated DNS names to these machines.

Once in a while, the machines that come up doesn't have either a TT or DN daemons running. They would have failed at startup for variety of reasons. The task was to find that missing hosts (generally 1 or 2) of the lot. So I wrote a script that would help us get the missing hosts which don't run one of the process.

Gist -