This document summarizes the functionality and issues of the General Availability (GA) version of Sun Java™ Real-Time System (Java RTS) 2.0_01. To ensure that you have the most recent update of this document, check the latest version on the Java SE Real-Time Product Documentation web site.

Java RTS is Sun's implementation of the Real-Time Specification for Java (RTSJ). The specification details for this implementation are described in Java RTS Implementation Details.

Java RTS 2.0_01 complies with JSR-01 Technology Compatibility Kit (TCK) 1.0.2 version SE 3.0.11, which tests the behavior of implementations of RTSJ version 1.0.2.

Contents

Operating Systems Supported
Java Virtual Machine Support
Functionality and Issues of Java SE 5.0
Enhancements in This Java RTS Release
General Differences from HotSpot
Functionality and Issues Specific to Java RTS
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[Readme File]   [Installation Guide]   [Compilation Guide]   [Garbage Collection Guide]   [Technical Information]   [Java RTS DTrace Provider]   [Practical Introduction to Achieving Determinism]

Operating Systems Supported

Java RTS 2.0_01 is supported on an UltraSPARC® processor or on a Sun x86/x64 platform running one of the following operating systems:

• Solaris™ 10 Operating System update 3, also called Solaris 10 11/06 (OS kernel version Generic_118855-33 on x86, Generic_118833-33 on SPARC)

• Solaris™ 10 Operating System update 4, also called Solaris 10 8/07 (OS kernel version Generic_127112-01 on x86, Generic_120011-14 on SPARC)

Refer to the content of the /etc/release file to determine the exact version of Solaris that is installed on your machine.

The OS kernel version is reported by the command uname -v.

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Java Virtual Machine Support

For the best temporal performance, we strongly recommend installing Java RTS on a machine featuring at least two processors.

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Functionality and Issues of Java SE 5.0

Java RTS 2.0_01 is generally based on the Java Platform, Standard Edition (Java™ SE) version 5.0 Update 13. Java SE 5.0 (also known as J2SE™ 5.0 or 1.5.0) is a major release of the Java platform containing new features and enhancements in many functional areas. Update releases are bug fix releases, which can include reliability, performance, and security fixes. The features, bugs, and workarounds of the Java SE 5.0 release and the additional fixes provided by Update 13 can be found at the J2SE 5.0 Release Notes web site.

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Enhancements in This Java RTS Release

Java RTS 2.0_01 provides the following enhancements to the previous version:

• Improved determinism for long-running applications.

• Application monitoring, management, and troubleshooting functionality. See the "Monitoring, Management, Troubleshooting" section of the Technical Information document.

• A new DTrace probe provider for Java RTS. The document Java RTS DTrace Provider contains a detailed description of these probes and how to use them, as well as several sample scripts.

• New MXBean to toggle between deterministic and debugging modes. See the "Balancing Determinism and Debugging" section of the Technical Information document.

• Modified acquisition of inherited access control for no-heap real-time threads. See the "Security" section of the Technical Information document.

• Minor bug fixes.

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General Differences from HotSpot

General differences in the behavior of Java RTS as compared with the HotSpot VM are as follows:

• The default values for the command-line parameters have been tuned for Java RTS and might differ from the default values in HotSpot. For example, the default values for -Xms and -Xmx have been increased for Java RTS.

• All the memory that is specified by the -Xms and -Xmx parameters is acquired and locked at initialization of the VM.

• Java RTS has limited support for the monitoring, management, and troubleshooting tools. See the "Monitoring, Management, Troubleshooting" section of the Technical Information document.

• Because of NHRTs, classes and interned strings are never garbage-collected. The RTSJ also prevents objects allocated in static initializers from being garbage-collected. You should be aware that such objects are allocated in immortal memory and survive until the JVM exits.

• The only compiler that Java RTS provides is the client compiler. The server compiler depends on non-deterministic optimization and has therefore been deactivated.

• Just-In-Time (JIT) compilation is asynchronous by default. See the Compilation Guide for details.

• Java RTS provides the implementation of variants of inline caches and virtual method inlining. These variants are especially intended for use with the Real-Time Garbage Collector. See the Compilation Guide for details.

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Functionality and Issues Specific to Java RTS

Java RTS differs in functionality from Java SE and the Java HotSpot™ VM in a number of areas, including clocks, timers, class initialization, memory management, and scheduling. In addition, certain issues, such as programming considerations, limitations, bugs, and workarounds, are applicable only to Java RTS. The Technical Information document summarizes the functionality and issues that are specific to Java RTS.

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