Experience with non-Sun / Oracle JVM?

Question

Beyond Websphere, the Sun / Oracle JVM seems almost ubiquitous. Do people have a lot of experience with other JVM implementations like OpenJDK or IBM JVM?

Any pitfalls? Differences in performance? Mistakes?

Answer 1

I used IBM, it comes with WebSphere and works well. I also used IBM in the past (1.1), it was faster than Sun. If you use Weblogic, you use JRockit, which is also fast. There is no difference that can be perceived. For performance, you will need to compare your application for different JVMs. You can probably get higher performance differences by running your code through the profiler.

Answer 2

I remember using the Microsoft JVM in the days of Java 1.1. Trying to debug it in Visual Studio this day was a nightmare with a CPU crisis. Now that I got it from my chest, we will never talk about it again.

Answer 3

I used the IBM JDK and JRE for two reasons. This is the one that manages all IBM products (Websphere, Rational, etc.), and connecting to the mainframe is much better.

Also, I used a non-Sun JVM in Ubuntu at home, but now I started using Sun (or Oracle now, I think).

Personally (and this is just an opinion), I would prefer to use Sun for battery life. For things like Websphere, it's best to use the one that comes as part of the product.

Answer 4

OpenJDK is the same code base as the Sun / Oracle JDK (you may have slight differences in release versions). The main difference is that the Sun JDK / JRE comes with fonts that are not related to OpenJDK (probably due to font licenses).

I also tested some applications for the Sun JVM and IBM JVM (1.4) for some time: the IBM JVM seemed to have a more aggressive system embedding strategy that gave it better performance results for this particular application (essentially a relatively short calculation in the loop over the array). As always, this type of result should be taken with caution, as it will depend on the application.