Robert Cates wrote:
I'm definitely not a HUGE expert in this field, but I know in no uncertain terms that the issue is how _Linux_ handles threads vs. processes. We run multiple versions of Sun's JDK on both RH 7.3 and RH 9 (all installed from our single software repository). That's to say that the version of JDK 1.4.1_03 running on RH 7.3 is the same binary as that running on RH 9. Newer versions of the Kernel and/or libraries simply handle threading differently.I would also like to mention that your issue with the Java PIDs I believe to be more of an issue with the Java SDK/JVM/JRE version you have installed. I'm not going to pretend to be an expert, but I seem to remember reading about the new Java version out now, and it's improvements, which includes much better handling of threads (version 1.4.x). I would be interested to know which Java version you had/have installed on your RH 7.3 machine(s), and then on your RH 9 machine(s).?
Threading did change within the JDK a long time ago from so-called "green" threads (fake threads internal only to the JVM itself) to "native" threads (real, OS mapped threads that run directly on the processor). However the behavior of having Linux assign a unique PID to each thread in older versions is not unique to Java -- you can see the same behavior in any threaded Linux app on, say, RH 7.3. You're just not as apt to notice them since a given threaded application isn't as likely to have such a significant numberof threads as is a JVM.
I think we will ultimately do a myriad of testing before putting anything in production, to say the least. At this point, we're in the "almost entirely theoretical" stage of learning/testing/etc. What I've written so far is just my initial reaction to having installed Debian under VMWare for the first time, taking a look around, getting a feel for the installation process and the like. I need to get from where I am to where I can confidently do a test installation on real iron and then start throwing some real tests at it. The first thing I saw was Linux 2.2 and ext2fs which immidiately brought-out a host of problems we've had in the past that have been naturally solved by the evolution of Red Hat versions. Seeing that kernel 2.4 is available is a big help, I just missed it while glossing over the manual, maybe my first lesson is to RTFM better!Lastly, what do you think of the idea of first building one machine with Debian 3.0r2 with kernel 2.4.18-bf2.4 and Java SDK/JRE 1.4.2_02 and everything else you need, test for a reasonable amount of time, then convert the rest.?
-Fred Whipple