COMPAQ

Release Notes
Compaq Fast Virtual Machine (Fast VM) v 1.3.1-beta
for Linux® Alpha
for the Java™ Platform

 Tux, created by Larry Ewing

Contents

Introduction

Thank you for downloading the Compaq Fast Virtual Machine (Fast VM) v 1.3.1-beta for Linux® Alpha for the Java™ Platform (hereafter called the Compaq Fast VM or, simply, the Fast VM). This beta kit is for use with the Compaq Software Development Kit v 1.3.1-1 for Linux® Alpha for the Java™ Platform (hereafter called the Compaq SDK or, simply, the SDK). This beta release does not provide a Fast VM kit for use with the Compaq Run Time Environment (RTE).

The Fast VM uses Just-In-Time (JIT) compiler technology designed to provide optimal Java runtime performance on Linux systems.

An HTML version of these release notes is placed in the following directory on the system where the Fast VM kit is installed:

J2SDKHOME/docs

where J2SDKHOME is the directory in which the SDK is installed.

IMPORTANT: Please make sure you understand the copyright (copyright.txt, installed file) and the license (license.txt, installed file) before using this release.

This Fast VM v 1.3.1-beta kit is a beta release of the Compaq Fast VM v 1.3.1 and is not intended for production use.

Hardware Requirements

Following is a list of the hardware components required for the installation of the Fast VM v 1.3.1-beta:

  Processor: Alpha processor (21164A and higher) 
  Memory: Recommended minimum 64 MB RAM 
  Disk Space: ~120 MB minimum 
  Video: 16-bit color

Software Requirements

This kit requires that the SDK be installed and running. This kit has been tested on RedHat 6.2 and 7.1 and SuSE 7.1 systems with glibc-2.1.95 and glibc-2.2.4.

Installing the Fast VM

The Fast VM v 1.3.1-beta kit is provided as a gzipped tar-ball.

To install the Fast VM v 1.3.1-beta, perform the following steps:

  1. Save the downloaded package as fastjvm131-beta.tgz.
  2. cd J2SDKHOME, where J2SDKHOME is the directory where the Compaq SDK was installed.
  3. Run tar xvzf fastjvm131-beta.tgz.
  4. Verify that you now have the following files:
    J2SDKHOME/jre/lib/alpha/fast/libjvm.so
    J2SDKHOME/jre/lib/alpha/fast/libjvm_g.so
    J2SDKHOME/jre/lib/alpha/fast/Xusage.txt
    J2SDKHOME/docs/java-fast/compaq.gif
    J2SDKHOME/docs/java-fast/copyright.txt
    J2SDKHOME/docs/java-fast/licence.txt
    J2SDKHOME/docs/java-fast/penguin.gif
    J2SDKHOME/docs/java-fast/release_notes.html

Using the Fast VM

Before using the Fast VM, you need to ensure that Compaq SDK v 1.3.1 is installed as described in the Compaq SDK v 1.3.1 Release Notes.

Ensure that the directory where SDK v 1.3.1 is installed is in your PATH and is searched before any other Java installation. For example, using csh(1): 

setenv PATH J2SDKHOME/bin:$PATH

Use the java -version command option. The following message is displayed: 

% java -version  
java version "1.3.1" 
Java(TM) 2 Runtime Environment, Standard Edition
Classic VM (build 1.3.1-n, native threads, jit)

where n identifies the specific Compaq SDK v 1.3.1 that is installed. For example, using csh(1): 

setenv PATH J2SDKHOME/bin:$PATH

For additional information about defining your PATH or specifying the pathname on the command line, see Using the SDK on Linux Alpha Systems in the Compaq SDK v 1.3.1 Release Notes.

After downloading and installing the Fast VM kit, the java -fast -version command displays the following: 

java version "1.3.1"
Java(TM) 2 Runtime Environment, Standard Edition
Fast VM (build 1.3.1, native threads, mixed mode, ...)

Using the java Command to Invoke the Fast VM

You invoke the Fast VM with the java -fast command as follows: 

java -fast 
Usage: java -fast [-options] classname [args]

Any arguments that appear after classname on the command line are passed to the main method of the class.

Standard Options

The java -fast command supports the following standard options:

Standard Options
Option Function
-classpath classpath
-cp classpath		 Specify a list of directories, JAR archives, and ZIP archives to search for user class files. Class path entries are separated by colons (:). Specifying -classpath or -cp overrides any setting of the CLASSPATH environment variable.

If -classpath and -cp are not used and CLASSPATH is not set, the user class path consists of the current directory (.).

-Dproperty=value Set a system property value.
-help Display usage information and exit.
-jar Execute a program encapsulated in a JAR file. The first argument is the name of a JAR file instead of a startup class name. In order for this option to work, the manifest of the JAR file must contain a line of the form Main-Class: classname.

Here, classname identifies the class having the public static void main(String[] args) method that serves as your application's starting point.

When you use this option, the JAR file is the source of all user classes, and other user class path settings are ignored.

-verbose
-verbose:class		 Display information about each class loaded.
-verbose:gc Report on each garbage collection event.
-verbose:jni Report information about use of native methods and other Java Native Interface activity (JNI). (This option can be specified but it has no effect.)
-version Display version information and exit.
-showversion Display version information and continue.
-X Display usage information for non-standard options and exit.

Non-Standard Options

This version of the Fast VM also includes support for the following java -fast non-standard options.

Non-Standard Options
Option Function
-Xbootclasspath:<bootclasspath> Specify a colon-separated list of directories, JAR archives, and ZIP archives to search for boot class files. These are used in place of the boot class files included in the Compaq SDK v 1.3.1 software.
-Xms<size> Specify the initial size of the memory allocation pool. This value must be greater than 1000. To multiply the value by 1000, append the letter k. To multiply the value by 1 million, append the letter m. See Dynamic Heap Settings for information about the default value.
-Xmx<size> Specify the maximum size of the memory allocation pool. This value must be greater than 1000. To multiply the value by 1000, append the letter k. To multiply the value by 1 million, append the letter m. See Dynamic Heap Settings for information about the default value.
-Xss<number> Set the maximum stack size for any thread.
-XO Do not generate stack trace information for exceptions.

If the Fast VM is not installed, the use of the java -fast command results in an error message indicating that -fast is an illegal argument.

The JAVA_FAST_VM Environment Variable

You can use the Fast VM by defining the environment variable JAVA_FAST_VM. If this environment variable is defined, the Fast VM is always used when the java command is invoked even if -fast is not specified, and the Java tools always use the Fast VM.

Dynamic Heap Settings

Rather than use fixed values for the default settings for the memory allocation pool (Java heap), the Compaq Fast VM determines the defaults for the initial heap size (-Xms) and the maximum heap size (-Xmx) dynamically based on the environment in which it is executing as shown below: 

max_memory = min ( physical memory on machine, total memory available to the  
process)
  
default initial heap size = 10% of max_memory
  
default maximum heap size = 60% of max_memory

By setting heap size defaults automatically, the Fast VM adjusts the heap size based on the amount of memory that is available. This generally produces better results than specifying fixed -Xmx and -Xms values, especially for an application that is executed on different systems with varying amounts of memory. It is sometimes possible to obtain better results by specifying -Xmx and -Xms rather than letting the Fast VM pick the defaults. To determine what values to use you should use the -verbosegc command line option to monitor your application's heap activity. If you notice that a large number of garbage collections are occurring, increase the heap size as much as possible without causing excessive page faults.

Restrictions

Native methods used with the Fast VM must conform to the Java Native Interface (JNI) specification on Sun's site. The Fast VM does not support native method conventions older than the JNI specification.

Problem Reporting

To report bugs or feature requests, refer to the Contact Us page on our web site.

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