Hi,
Here is our final port of JDK 1.1.7 with Native Threads! Both Scott and I
have signed Steve Byrne's License to get 1.2 sources and will start its
port soon.
Here are the key parts of the release note (sorry for the length).
Thanks,
Your Blackdown JDK PPC Porters:
Scott Hutinger and Kevin B. Hendricks
New in this Port
----------------
* This is our final port of Sun's JDK 1.1.7 final.
- Native Threads support is HERE!
- enable by: export THREADS_FLAG=native
- please give a special thanks to Phill Edwards of the
Blackdown Java-Linux team for creating the
Native Threads port. Great job Phill!
- fix for image scaling problem
- fix for hanging stdout and stderr (green_threads)
- fix for kernel accept() bug, caused slow Java Web Server
- turn-off by: export JDK_NO_KERNEL_FIX=true
Also a special thanks goes to Juergen Kreileder for almost all of the
work to get the 1.1.6 diffs to work on 1.1.7 with no regressions!
And thanks, of course, go to the Blackdown Porters in general
for all of their valuable work in porting the JDK to Linux.
Native Threads vs Green Threads
-------------------------------
This release includes both green and native threads. Green threads are
user based theads that have been part of the JDK since its inception.
Green threads are very stable, have a lower memory footprint, and
involve much lower overhead for creation and context switching.
Native threads are linux threads (one-to-one implementation of pthreads)
and are kernel based. Each thread is basically a clone of the its
parent process and therefore has a higher overhead for context
switching and creation and a larger memory footprint. Because they
are processes, the number of threads is limited by the number of
processes/tasks built into the Linux kernel. You will have to recompile
your kernel to handle larger number of threads.
So why use native threads? Native threads deal better with some JNI
native C programs than green_threads because you do not have to make
all io non-blocking and therefore do not have to redefine all of the
system calls related to io. But the main reason to use native
threads is that on multi-processor systems, native threads can be
easily split among processors greatly improving performance while
green_threads can not. Although on single processor systems, green
threads will probably be faster for most programs.
Native Threads Requirements
---------------------------
As a result of Phill Edwards hard work, we now have native threads
support for the Linux JDK ports. The native threads port itself
should be considered beta quality (or better). To make use of it
you MUST upgrade to the following packages:
- glibc (1m) (the very latest glibc from Gary Thomas with thread fixes)
- X11R6.3 (1s) (the X11R6.3 (1r) rpms rebuilt with -D_RENTRANT
- David Gatwood's latest MkLinux kernel/server pair or Paul's latest
2.1.24 kernel or Paul's latest 2.1.125 kernel
All of these packages are available from the following mirror site:
ftp://ftp.mklinux.apple.com/pub/contrib/JDK/
Note: The Metrowerks JIT has not been tested with the Native Threads
port. If you run into problems, please try disabling it to see
if the problem goes away an then either file a bug report on the JIT or
the native threads.
*************************************************************
* NOTE: In keeping with the Metrowerks binary license, the *
* Metrowerks JIT is not longer shipped with the JDK and *
* therefore is NOT installed by default. To use the JIT *
* with the JDK please download the Metrowerks JIT binary *
* archive and follow the instructions in the README. *
*************************************************************
* This port is statically linked with Motif 2.1.
* This port was developed under Sun's non-commercial license agreement.
The home website is still:
http://business.tyler.wm.edu/mklinux
We hope you enjoy the numerous improvements available in JDK 117.
We will continue to work to both improve the port and fix bugs.
Thanks,
Your MkLinux / Linux PowerPC JDK Porting Team
Scott Hutinger and Kevin B. Hendricks
----------------------------------------------------------
Kevin B. Hendricks
Associate Professor, Operations & Information Technology
School of Business, College of William & Mary
Williamsburg, VA 23187, [EMAIL PROTECTED]
http://business.tyler.wm.edu
