Re: Volano Report update

[Christopher Smith]

Juergen Kreileder wrote: Christopher Smith <[EMAIL PROTECTED]> writes: On Tue, 2003-06-03 at 19:29, John Neffenger wrote: Hi Bill, Also, 2.5.x Linux has changes to their 1:1 model that greatly increases scalability for dealing with a large number of threads. I was under the impression that Java application developers will have to wait for the Java virtual machines to take advantage of those threading changes before we see any benefits. I read that IBM needs to make changes in their Java VM on Linux to support it, for example. Is that correct? That is my understanding right now. The latest JVM's from Sun and IBM apparently take steps to disable NPTL. Huh? RH 9 already uses NPTL, Sun and Blackdown JVMs work on it. (I don't know about IBM's.) To clarify: yes, RH9 has NPTL. However, NPTL changes the behavior of threading on Linux (actually makes it more POSIX compliant). These subtle changes in behavior tend to cause problems with complex software that is tightly tied to the underlying thread model. Certainly the existing Linux JVM's have had a LOT of tweaking done to them in order to deal with "differences" in Linux's thread model. This is also a problem for the WINE project (as another example). So, the simple thing to do is disable NPTL and use the old, less scalable thread model (basically you just set an environment variable and magically glibc uses LinuxThreads-style pthreads). It's my understanding that the Sun JVM does this, as does the WINE project. I am not certain about the IBM VM, but since they have not released a new VM since NPTL was released on a mainstream Linux platform (RH9), I suspect this is not the case. Someone who knows more, please let me know. I suspect that prior to NPTL being usable, changes will have to be made both the VM and the standard libraries. Perhaps with luck Sun/IBM/etc. can just use code from other POSIX platforms. I don't know. --Chris