HP-UX Programmer's Guide for Java 2
Table Of Contents
- Table of Contents
- 1 Introduction
- 2 HotSpot Technology Tools and Commands
- 3 Configuration for Java™ Support
- 4 Performance and Tuning
- 5 Measuring System Performance
- 6 Using Threads
- 7 Using Signals
- 8 Using Java™ 2 JNI on HP-UX
- 9 Expanding Memory
- Determine your requirements
- Memory layout under HP-UX 11.0 (PA-RISC only)
- Additional memory available under HP-UX 11i (PA-RISC only)
- Allocating physical memory and swap in the Java™ heap
- Useful key command-line options for allocating memory
- Application-dependent considerations using large heap size HP-UX 11i PA-RISC
- Expanding heap size in native applications on PA-RISC HP-UX 11.11 and later releases
- Expanding heap size in native applications on Integrity HP-UX 11.23 and later releases
- Expanding heap size in HP-UX PA-RISC
- Expanding heap size in HP-UX Integrity
- 10 Diagnosing Memory Leaks
- A JDK/JRE 6.0.n and 7.0.n Usage Notes
- Using Java 2 JNI on HP-UX
- Garbage collection
- Asian TrueType fonts and Asian locales
- Date/Time methods defaults
- Profiling
- Compatibility with previous releases
- Java Cryptography Extension (JCE) policy files
- Configuring the Java Runtime Plug-In
- CLASSPATH environment variable
- Java Web Start technology usage
- Upgrading from a previous Java Web Start version
- IPv6 support
- Allocation Site Statistics and Zero Preparation -Xverbosegc
- JDK 6.0.04 flags
- GC log-rotation support
- NUMA collector enhancements
- ThreadDumpPath support
- Garbage-First garbage collector (-XX:+UseG1GC)
- jmap, jinfo, and jstack tools included in JDK 6.0.03
- Additional Java Web Start documentation
- B JDK/JRE 5.0.n Usage Notes
- Using Java 2 JNI on HP-UX
- Garbage collectors: Parallel and Concurrent Mark Sweep
- Allocating physical memory and swap in the Java heap
- Asian TrueType fonts and Asian locales
- Date/Time methods defaults
- Profiling
- Closing a socket (PA-RISC only)
- Compatibility with previous releases
- Java Cryptography Extension (JCE) policy files
- Allocation Site Statistics and Zero Preparation -Xverbosegc
- IPv6 support on Java 5.0
- GC log-rotation support in 5.0
- ThreadDumpPath support in 5.0
- Dynamically loaded libraries in 5.0
- Performance improvement for String.intern()
- Configuring the Java Runtime Plug-In
- CLASSPATH environment variable
- Java Web Start technology usage
- C SDK/RTE 1.4.2.n Usage Notes
- Removing support for unwanted architectures in the JRE
- Support for dynamic thread local storage (TLS)
- Signal Chaining functionality
- Using Java 2 JNI on HP-UX
- HotSpot JVM options
- Garbage collectors: Parallel and Concurrent mark sweep
- Allocating physical memory and swap in the Java heap
- Asian TrueType fonts and Asian locales
- Date/Time methods defaults
- Profiling
- Closing a socket when accept or read is pending (PA-RISC) - new patch information!
- Compatibility with previous releases
- Runtime Plug-In usage and configuration
- GC log-rotation support
- ThreadDumpPath support
- D Additional Resources
- Index
To enable this functionality, use the command-line option -XX:+HeapDump or set the
environment variable _JAVA_HEAPDUMP=1 before starting the Java™ application. (for
example, export _JAVA_HEAPDUMP=1)
This output is similar to -Xrunhprof:heap=dump. The difference is that the thread
info (THREAD START) and trace info (TRACE) will not printed to the output file.
With the option enabled, each time you send the process a SIGQUIT signal the JVM
produces a dump of the Java™ heap (a Java™ heap snapshot), in hprof format. The
name of the file will have the following format:
java_<pid>_<date>_<time>_heapDump.hprof.txt
By creating a series of these snapshots you can see how the number and size of objects
varies over time.
NOTE: A full GC is executed prior to the Heap snapshot.
-XX:+HeapDumpOnly and _JAVA_HEAPDUMP_ONLY
Beginning with SDK 1.4.2.11, the option -XX:+HeapDumpOnly can be used to enable
HP Heap Dumps using SIGVTALARM signal (signal 20). To enable this feature without
altering the java command line, the environment variable _JAVA_HEAPDUMP_ONLY
can be set in the user's environment prior to executing the java application java.
If _JAVA_HEAPDUMP_ONLY is set, or -XX:+HeapDumpOnly command-line option is
used, then the HP HeapDump functionality will be triggered by sending signal
SIGVTALRM (20) to the process, and the printing of thread and trace information to
stdout is suppressed.
The HeapDump is written to a file with the following filename format:
java_<pid>_<date>_<time>_heapDump.hprof.txt
The default output format is ASCII. The output format can be changed to hprof binary
format by setting the _JAVA_BINARY_HEAPDUMP environment variable, which is used
to specify that heap dumps be emitted in binary format only. By default the
-XX:+HeapDump and -XX:+HeapDumpOnly options will emit heap dump information
in ascii format.
-XX:+HeapDumpOnCtrlBreak
The command-line option -XX:+HeapDumpOnCtrlBreak enables the ability to take
snapshots of the java heap when a SIGQUIT is sent to the java process, without using
the jvmti-based -Xrunhprof:heap=dump.
This feature is similar to the -XX:+HeapDump option, except the output format is binary
hprof format, and is placed into a filename with the following naming convention:
The HeapDump is written to a file with the following filename format:
java_<pid>_heapDump.hprof.<millitime>
22 HotSpot Technology Tools and Commands