A while ago I had to read data from a MySQL table, do a bit of manipulations on that data and store the results on the disk. The obvious choice was to use Spark, I was already using it for other stuff and it seemed super easy to implement. This is more or less what I had to do (I removed the part which does the manipulation for the sake of simplicity): Looks good, only it didn’t quite work. Either it was super slow or it totally crashed depends on the size of the table. Tuning Spark and the cluster properties helped a bit, but it didn’t solve the problems. Since I was using AWS EMR, it made sense to give Sqoop a try since it is a part of the applications supported on EMR. Sqoop performed so much better almost instantly, all you needed to do is to set the number of mappers according to the size of the data and it was working perfectly. Since both Spark and Sqoop are a based on Hadoop map-reduce framework, it was clear that Spark can work at least as good as Sqoop, I only needed to find out how to do Continue reading The right way to use Spark and JDBC
Working with AWS EMR has a lot of benefits. But when it comes to metrics, AWS currently does not supply a proper solution for collecting cluster metrics from EMRs. Well, there is AWS Cloudwatch of course, which works out of the box and gives you loads of EMR metrics. The problem with CloudWatch is that it doesn’t give you the ability to follow metrics per a business unit, or a tag, only per a specific EMR id. This simply means you can not compare the metrics over time, only for specific EMRs. Let me explain again the problem. A common use of EMR, is that you write some kind of code that will be executed inside an EMR, and will be triggered every given amount of time, lets say every 5 hours. This means that every 5 hours a new EMR, with a new ID will be spawned. In CloudWatch you can see each of these EMRs individually but not in a single graph, which is defiantly a disadvantage. Just to note, I am referring only to machine metrics, like memory, cpu and disk. Other metrics like jvm metrics or business metrics, are usually collected by the process itself and Continue reading How to properly collect AWS EMR metrics?