Sunday Sep 30, 2012

Talking JavaOne with Rock Star Kirk Pepperdine

Kirk Pepperdine is not only a JavaOne Rock Star but a Java Champion and a highly regarded expert in Java performance tuning who works as a consultant, educator, and author. He is the principal consultant at Kodewerk Ltd. He speaks frequently at conferences and co-authored the Ant Developer's Handbook. In the rapidly shifting world of information technology, Pepperdine, as much as anyone, keeps up with what's happening with Java performance tuning.

Pepperdine will participate in the following sessions:

  • CON5405 - Are Your Garbage Collection Logs Speaking to You?
  • BOF6540 - Java Champions and JUG Leaders Meet Oracle Executives (with Jeff Genender, Mattias Karlsson, Henrik Stahl, Georges Saab)
  • HOL6500 - Finding and Solving Java Deadlocks (with Heinz Kabutz, Ellen Kraffmiller Martijn Verburg, Jeff Genender, and Henri Tremblay)


I asked him what technological changes need to be taken into account in performance tuning. “The volume of data we're dealing with just seems to be getting bigger and bigger all the time,” observed Pepperdine. “A couple of years ago you'd never think of needing a heap that was 64g, but today there are deployments where the heap has grown to 256g and tomorrow there are plans for heaps that are even larger. Dealing with all that data simply requires more horse power and some very specialized techniques. In some cases, teams are trying to push hardware to the breaking point. Under those conditions, you need to be very clever just to get things to work -- let alone to get them to be fast. We are very quickly moving from a world where everything happens in a transaction to one where if you were to even consider using a transaction, you've lost."

When asked about the greatest misconceptions about performance tuning that he currently encounters, he said, “If you have a performance problem, you should start looking at code at the very least and for that extra step, whip out an execution profiler. I'm not going to say that I never use execution profilers or look at code. What I will say is that execution profilers are effective for a small subset of performance problems and code is literally the last thing you should look at.

And what is the most exciting thing happening in the world of Java today? “Interesting question because so many people would say that nothing exciting is happening in Java. Some might be disappointed that a few features have slipped in terms of scheduling. But I'd disagree with the first group and I'm not so concerned about the slippage because I still see a lot of exciting things happening. First, lambda will finally be with us and with lambda will come better ways.”

For JavaOne, he is proctoring for Heinz Kabutz's lab. “I'm actually looking forward to that more than I am to my own talk,” he remarked. “Heinz will be the third non-Sun/Oracle employee to present a lab and the first since Oracle began hosting JavaOne. He's got a great message. He's spent a ton of time making sure things are going to work, and we've got a great team of proctors to help out. After that, getting my talk done, the Java Champion's panel session and then kicking back and just meeting up and talking to some Java heads."

Finally, what should Java developers know that they currently do not know? “’Write Once, Run Everywhere’ is a great slogan and Java has come closer to that dream than any other technology stack that I've used. That said, different hardware bits work differently and as hard as we try, the JVM can't hide all the differences. Plus, if we are to get good performance we need to work with our hardware and not against it. All this implies that Java developers need to know more about the hardware they are deploying to.”

Originally published on blogs.oracle.com/javaone.

Tuesday Oct 25, 2011

Perspectives on Garbage Collection

In a new article, part of the Developer Insight series, and titled “The Developer Insight Series, Part 6: Perspectives on Garbage Collection,” now up on otn/java, three leading Java developers offer insight into garbage collection.

Oracle Lab’s Ron Goldman notes, that, “Although automatic memory management has existed for more than 50 years, a lot of people still don't want it in their systems because it seems inelegant. It just strikes people as wrong – ‘It's my memory. I should be releasing it when I know it's no longer being used.’ Theoretically, that might be true, but in practice, programmers continue to forget to free up memory when they are done with it, or, even worse, try to free it up while it's still in use. The results? Buggy code that is apt to crash unexpectedly.”

Java Champion Kirk Pepperdine observes that, “Even though collection of very short-lived objects is almost free, high rates of object churn can still result in very inefficient GC numbers. Sometimes, the problem is simply that the Java Virtual Machine (JVM) doesn't have enough heap space. Monitoring GC activity will give you the hints you need for a successful heap-sizing exercise…”

And Oracle’s GC expert Tony Printesiz takes on eight myths about garbage collection, four of which are:

1. Reference counting GC will solve all my latency problems.
2. malloc and free will always perform better than GC.
3. Finalizers should be called promptly, as soon as objects become unreachable.
4. GC will eliminate all memory leaks.

The article provides a good context for developers to collect their thoughts about garbage. ;)

Read the complete article here.

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