HP-UX Programmer's Guide for Java 2

B JDK/JRE 5.0.n Usage Notes
This appendix provides usage notes for the HP-UX Java™ JDK/JRE 5.0.n version stream.
Using Java 2 JNI on HP-UX
For C and C++ applications, it is important to link with the -mt (multithread) option
if the application calls a Java VM. Both executables and shared libraries must be linked
with -mt. Use of -mt must be consistent during both compilation and linking. For more
information, see “Native (non-Java) calling Java™ methods” (page 52).
If you embed libjvm in a 32-bit native application and wish to use a large Java heap,
you must link with the -N option. For more information, see “ Expanding heap size in
native applications on PA-RISC HP-UX 11.11 and later releases” (page 67) and
“Expanding heap size in native applications on Integrity HP-UX 11.23 and later releases”
(page 67).
Garbage collectors: Parallel and Concurrent Mark Sweep
For a summary of changes in the garbage collector for version 5.0 refer to http://
download.oracle.com/javase/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” (page 64).
Asian TrueType fonts and Asian locales
Asian locales are supported by JDK 5.0.22 with TrueType fonts. For more details, see
HP-UX Fonts and the Java™ Runtime Environment at:
http://www.hp.com/go/hpux-java-docs
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 the date command, adjtime() function,
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.
82 JDK/JRE 5.0.n Usage Notes