OpenJDK will be the reference JDK going forward but there are still a ton of differences in the way java apps work on the Oracle JDK vs the OpenJDK. Flat out you'll just run into weird bugs and 1.2.0 wouldn't even start with OpenJDK7

From: Ilya Grebnov <>
Reply-To: "" <>
Date: Tuesday, February 5, 2013 2:09 PM
To: "" <>
Subject: RE: Why do Datastax docs recommend Java 6?

Also, what is particular reason to use Oracle JDK over Open JDK? Sorry, I could not find this information online.




From: Michael Kjellman []
Sent: Tuesday, February 05, 2013 7:29 AM
Subject: Re: Why do Datastax docs recommend Java 6?


There have been tons of threads/convos on this.


In the early days of Java 7 it was pretty unstable and there was pretty much no convincing reason to use Java 7 over Java 6.


Now that Java 7 has stabilized and Java 6 is EOL it's a reasonable decision to use Java 7 and we do it in production with no issues to speak of.


That being said there was one potential situation we've seen as a community where bootstrapping new node was using 3x more CPU and getting significantly less throughput. However, reproducing this consistently never happened AFAIK.


I think until more people use Java 7 in production and prove it doesn't cause any additional bugs/performance issues Datastax will update their docs. Until now I'd say it's a safe bet to use Java 7 with Vanilla C* 1.2.1. I hope this helps!





From: Baron Schwartz <>
Reply-To: "" <>
Date: Tuesday, February 5, 2013 7:21 AM
To: "" <>
Subject: Why do Datastax docs recommend Java 6?


The Datastax docs repeatedly say (e.g. that Java 7 is not recommended, but they don't say why. It would be helpful to know this. Does anyone know?


The same documentation is referenced from the Cassandra wiki, for example,


- Baron