Category Archives: java

The Long Dark

If there is one thing I’ve learned from the Kato project, it’s that open source software needs a community with the motivation to participate. Unfortunately with the acquisition of Sun by Oracle, JSR-326 has been held up as we really needed Sun/Oracle to participate. Of course, the Apache Kato incubator is not JSR-326, but the two were tied together, and the outcome of Kato was to produce JSR-326’s reference implementation.

So what has happened after the 0.1 release of Kato? Well, conversations have been had between representatives from IBM and Oracle, led by Steve Poole. Events have been progressing extremely slowly, as Java debugging in the manner of Apache kato hasn’t been a huge priority – Java 7.0 has been the highest priority. My hope is that the once Java 8 gets the focus JSR-326 and Kato will get some attention. Oracle have apparently assigned someone to work on this – we look forward to hearing from him.

Robert Burrell Donkin has continued to show superhuman levels of patience with his encouraging words. Even with months and months of activty he continues to encourage us. The original goals of this project were worthy enough, but I believe it would have been better for us to develop the technology, open-source it for collaboration in an Apache Incubator, and then consider standardizing it. One of the options considered was to ignore the JSR for now and continue developing cool technology – I would like to explore that idea.

Personally, there has been a lot going on since 0.1. In IBM I’ve occupied three different roles (none of them in JVM technology). I also managed to get married and my baby daughter was born in June this year! So doing open-source projects in your free time has proven difficult when free time is in such short supply.

So, to the future:

I believe JSR-326 will probably be completed. However, it would be advantageous if we reevaluated it’s goals in light of developments since this project started. One area we could consider addressing is debugging in cloud environments.

I’d like to see Apache Kato decoupled from JSR-326 if the JSR does not seem likely to continue – a new JSR could be submitted if the Apache Kato technology proved valuable enough for standardization.

OpenJDK will continue as is, and we need to consider our relationship with it carefully. Technology embedded in the JDK would be GPL licensed. The code that tooling would use to interact with OpenJDK would be best distributed with a permissive licence, i.e. Apache, so that tools development could be collaborated on. I imagine this will turn out to be a mine field, so we shall see.

So here’s to the next quarter – may it be more interesting that the last 6!

Signs and Portents

It has been a very long time since my first post.

Most of the work I’ve been doing on the Kato project has been on the Early Draft Review of  JSR-326 (available here: JSR-326).

More interestingly, in IBM here we’ve had a summer student (Paul Sobek – I don’t have a link to him) writing a JVMTI agent in C that dumps all sorts of Java goodness. Our problem was with hprof there wasn’t quite enough information for our needs, and the information is offered was limited. Using  his agent it is now possible to inspect local variables at the time a dump was taken.

Ultimately, we’d like this to be our Reference Implementation, after much more testing against our TCK and implementation of non-JVM information (such as the machine’s hostname). In combination with our JDI connector, it is possible to attach a Java debugger to the dump files and determine what caused them.

Would this be something you want? For example, take a long running server. If an ArrayIndexOutOfBounds exception is thrown, then either the JVM will exit, or it will be caught and ignored. Using this agent, a dump could be taken automatically, and offline it could be debugged.

Soon I hope to write here how you can try this out for yourself…