On 9/14/07, Mark Post <[EMAIL PROTECTED]> wrote: > It was Rob working with me on the Linux/390 wiki system that led him to the > discovery that the IBM JDK was issuing 10ms sleeps. It wasn't just in the > newer versions of the JDK, it was in the 1.4.2 ones as well. So, upgrading > to a newer version of WAS and it's associated Java, shouldn't be any worse in > that regard.
He's back now... ;-) There are issues in some later JDK levels (not yet 1.4.2) and Velocity Software have a bypass for it - IBM is working on getting the bypass supported and eventually fix the problem. And there are problems in applications. In the Open Source Java application Mark and I looked at, I could identify the cause and repair it. With later versions of WAS (after 4.5) there are similar problems. And with closed source like WAS I can only identify it and yell at developers who may listen but do not understand. Because each Java application seems to ship with its own copy of the JVM, it's not always easy to understand whether its the JVM or the application. But it may not be relevant either where the problem is, unless you're in a position to fix it... Oh, and part of IBM's DB2 also has such problems, even though it's not in Java. IMHO the cause is a skills problem with the developers. Poorly written code they can get away with on discrete servers, that is slightly noticed on simple virtualization like VMware, but impacts scalability when you get as advanced as we can do with z/VM. This is not easy stuff. Although Barton says people don't want to hear difficult explanations, I may need to sit down and write about it. Rob -- Rob van der Heij Velocity Software, Inc http://velocitysoftware.com/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
