| NOTE:
Some of the usage documentation previously included in these release notes has
been moved to the Java for HP-UX Programmer's Guide at Programmer's Guide for Java™ 2
The Java for HP-UX Programmer's Guide at Programmer's Guide for Java™ 2
contains usage documentation for developers. There you will find information on
HotSpot options, HP-specific optons and features, suggestions and examples for
allocating memory, how to use WDB to examine backtraces in Java threads, code
examples for using Java Native Interface, and much more.
Another change is that beginning with 5.0, we are combing the JDK, JRE, Runtime
Plug-in, and Java WebStart technology release notes in this document.
JDK/JRE Usage
Removing support for unwanted architectures in the JRE
Under the JRE license agreement, partners who redistribute the JRE may remove
support for unwanted architectures. Functional components may NOT be removed
under any circumstances. You may remove support for unwanted architectures as
follows:
The following commands assume that the JRE has been installed in the standard
location, i.e. /opt/java1.5/.
- On PA-RISC, to remove 64-bit support:
/usr/sbin/swremove Jre15.JRE15-PA20W
Jre15.JRE15-PA20W-HS
- On HP Integrity (Itanium), to remove 64-bit support:
/usr/sbin/swremove Jre15.JRE15-IPF64
Jre15.JRE15-IPF64-HS
Support for dynamic thread local storage (TLS)
Dynamic thread local storage is fully supported on all HP Integrity (Itanium)
systems, beginning with SDK Versions 1.4.2.00 and 5.0.
Dynamic TLS is not available on
any HP-UX PA-RISC system. However there is a workaround. Refer to "shl_load
HotSpot libjvm problem due to TLS (PA-RISC)" in these release notes
for details.
HotSpot JVM Options
For all standard and non-standard options, please refer to the Java for HP-UX
Programmer's Guide at HotSpot Technology Tools and Commands.
In 5.0, Class Data Sharing is not supported.
Signal Chaining Functionality
With signal chaining functionality, applications can now use signals that the
JVM uses and they will not interfere with the JVM's functionality. For signal
chaining, the application must load the library
libjsig.sl (PA) or libjsig.so
(Itanium) before libc.2.
On PA-RISC, to obtain this functionality, you need to install the patch shown
below and then use LD_PRELOAD. On
HP Integrity, no patch and no workaround is needed.
HP-UX 11.11 PA-RISC systems, install patch PHSS_28436 (or the patch that
supersedes it)
For examples and scenarios of how to use LD_PRELOAD, refer to the Java for HP-UX
Programmer's Guide at: Using Signals#chaining
Using WDB to examine backtraces in Java thread stacks
You can now use HP's debugger WDB 3.0.01 or later (the GNU Debugger
GDB) to examine backtraces containing mixed language frames (Java and
C/C++) in Java thread stacks. This will simplify debugging the VM and Java
mixed-language applications. Set the environment variable
GDB_JAVA_UNWINDLIB to the path name of the Java Unwind Shared Library
libjunwind.sl (PA), which is in the SDK.
The default location of the Java Unwind Library in the SDK is:
/opt/java1.5/jre/lib/PA_RISC/server/libjunwind.sl
/opt/java1.5/jre/lib/PA_RISC2.0/server/libjunwind.sl
/opt/java1.5/jre/lib/PA_RISC2.0W/server/libjunwind.sl
/opt/java1.5/jre/lib/IA64N/server/libjunwind.so
/opt/java1.5/jre/lib/IA64W/server/libjunwind.so
Here are a few examples. In ksh, you would set the environment variable like
this:
For 64-bit PA2.0 machines:
export export GDB_JAVA_UNWINDLIB=/opt/java1.5/jre/lib/\
PA_RISC2.0W/server/libjunwind.sl
For 64-bit Itanium 2 machines:
export GDB_JAVA_UNWINDLIB=/opt/java1.5/jre/lib/\
IA64W/server/libjunwind.so
If you installed the SDK in a location other than the default, you would
substitute the non-default location for "/opt/java1.5"
in the above commands. Then use WDB as usual to debug your Java applications or
core files. See the tutorial slides on Debugging at Performance Tuning, Tutorials, & Training for
help on how to use the new Java stack unwind functionality.
The Java for HP-UX Programmer's Guide at Programmer's Guide for Java™ 2
contains usage documentation for developers. There you will find information on
HotSpot options, HP-specific optons and features, suggestions and examples for
allocating memory, how to use WDB to examine backtraces in Java threads, code
examples for using Java Native Interface, and much more.
Please refer also to Sun Microsystems' Java HotSpot VM Options at http://java.sun.com/docs/hotspot/VMOptions.html.
Garbage collectors: Parallel, Concurrent mark, and Sweep
For a summary of changes in the garbage collector for version 5.0 refer to http://java.sun.com/j2se/1.5.0/docs/guide/vm/gc-ergonomics.html The parallel
collector
(-XX:+UseParallelGC)
has been enhanced in 5.0 to monitor and adapt to the memory needs of the
application in order to eliminate the need to tune command-line options to
achieve the best performance.
Allocating physical memory and swap in the Java heap
Since 1.4.1.05, the method of allocating physical memory and swap within the
Java heap has changed. As a result, you are likely to see higher
RSS (resident set size) memory usage when monitoring your Java
processes with Glance or other tools, or your application startup may be
slightly slower.
For more details on why this occurs and for examples of using key command line
options, see: Allocating Physical Memory and Swap in the Java Heap.
Asian TrueType fonts and Asian locales
Asian Locales are supported by HP's 5.0 JDK with TrueType fonts. For more
details, please refer to HP-UX Fonts and the Java™ Runtime Environment.
Date/Time methods defaults
The HotSpot JVM uses the gettimeofday()
system call to obtain date and time information. For performance reasons a new
mechanism that uses the number of CPU ticks since the application started is
used to calculate the current time. As a result, changes to the system date or
time using date(1), adjtime(2) or
time synchronization utilities such as ntp
will not be reflected in the date and time that the Java program returns, until
the process is restarted.
If your application requires that system time changes are immediately reflected,
you can use the
-XX:+UseGetTimeOfDay option to tell
the JVM to use the gettimeofday
call instead of the new, lightweight mechanism. However you may notice a drop in
performance.
Profiling
Currently a SIGPROF handler to
support future profiling capability is installed automatically. This may cause
incompatibilities with other native code or profiling tools which use
SIGPROF. You can turn off the
SIGPROF handler by using the following option
-XX:+ReduceSignalUsage
However be aware that using this option also turns off the SIGQUIT handler, and
you therefore will not be able to get a Java stack trace.
Closing a socket (PA-RISC only)
Because of changes to the mechanism by which a socket is closed in the VM, you
no longer need to use the
-XdoCloseWithReadPending option we recommended in earlier releases.
For further details, refer to the HP-UX Programmer's Guide at HotSpot Technology Tools and Commands#socket
Compatibility with previous releases
Sun Microsystems maintains upward compatibility, therefore an application
written for a 1.4 JVM will run on a 5.0 JVM. Downward compatibility is generally
not supported, because new API's are introduced that cannot be run on earlier
JVMs.
For a detailed description of the incompatibilities between 1.4 and 5.0, refer
to http://java.sun.com/j2se/1.5.0/compatibility.html
Configuring the Runtime Plug-In
For additional information on the Runtime Plug-In, refer to the Plug-In FAQs at
Java™ Runtime Plug-in (JPI) for 1.3, 1.4, 5.0, & 6.0 Frequently Asked Questions.
The JPI configuration has been redesigned in the 5.0 release. Please refer to
Sun Microsystems' documentation at:
http://java.sun.com/j2se/1.5.0/docs/guide/deployment/deployment-guide/jcp.html
CLASSPATH
A user's CLASSPATH environment
variable can be passed by the JVM by running the Control Panel and specifying
either '-cp' or '-classpath'
in the "Java Run Time Parameter" box. You need to exit and rerun the browser for
this change to take effect.
Java Webstart Technology Usage
Java™ Web Start is an application-deployment technology, which gives you the
power to launch full-featured applications with a single click from a web
browser. It is located in the jre directory. Some of Java Web Start's features
include:
- Runs independently of any browser, so you can shut down your browser or go
to another Web page and continue using your application.
- Applications deployed with Java Web Start do not require a browser interface
to operate.
- Includes security features of the Java 2 platform.
The hardware and operating system requirements for using Java Web Start are the
same as those recommended for J2SE platform implementation on which it runs.
Upgrading from a Previous Version
Do NOT uninstall your previous version of Java Web Start (if you have one)
before installing the new version. Uninstalling the previous version will cause
the download cache to be cleared, and all of the previously installed Java Web
Start applications will have to be downloaded again.
This version will overwrite previous installations and automatically update
browsers to use this new release. If you want to reactivate a previous version
after installing this new release, you have to re-install the old version. The
configuration files and program files folder used by Java Web Start have not
changed, so all your settings will remain intact after the upgrade.
Additional Java Web Start documentation
More information, including developer documentation, can be found in Sun
Microsystems' documentation at: http://java.sun.com/products/javawebstart/reference/index.html.
Additional HP and Sun documentation
The following websites have additional information:
Java man pages (located
at/opt/java1.5/man)
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