JRockit
Encyclopedia
JRockit, a proprietary Java Virtual Machine
(JVM) originally developed by Appeal Virtual Machines
and acquired by BEA Systems
in 2002, became part of Oracle Fusion Middleware
in 2008.
The JRockit code base and the HotSpot virtual machine from Sun Microsystems (now Oracle) are currently being integrated, with the target of releasing a JVM with a combined code base around the release date of JDK 8.
JRockit was made free and publicly available in May 2011.
Many JRE class files distributed with JRockit exactly replicate those distributed with HotSpot. JRockit overrides class files which relate closely to the JVM, therefore retaining API
compatibility while enhancing the performance of the JVM.
The overridden class files include those in the packages:
, Oracle
announced in JavaOne 2010
that the best features of JRockit would be implemented in OpenJDK
In May 2011, Oracle announced that JRockit has become free, confirming that they plan to port JRockit features on OpenJDK
s tend to show that server performance of HotSpot
was better, but that JRockit had a much better scalability.
The tools include:
From release R27.3 the tools suite also includes a latency analyzer that graphically visualizes when threads stall due to synchronization, file/network I/O, memory allocation and garbage collection pauses.
Java Virtual Machine
A Java virtual machine is a virtual machine capable of executing Java bytecode. It is the code execution component of the Java software platform. Sun Microsystems stated that there are over 4.5 billion JVM-enabled devices.-Overview:...
(JVM) originally developed by Appeal Virtual Machines
Appeal Virtual Machines
Appeal Virtual Machines was a Swedish company created in 1998 by students from the Royal Institute of Technology in Stockholm. They were mainly known for their JRockit Java Virtual Machine....
and acquired by BEA Systems
BEA Systems
BEA Systems, Inc. specialized in enterprise infrastructure software products known as "middleware", which connect software applications to databases and was acquired by Oracle Corporation on April 29, 2008.- History :...
in 2002, became part of Oracle Fusion Middleware
Oracle Fusion Middleware
Oracle Fusion Middleware consists of several software products from Oracle Corporation. OFM spans multiple services, including Java EE and developer tools, integration services, business intelligence, collaboration, and content management...
in 2008.
The JRockit code base and the HotSpot virtual machine from Sun Microsystems (now Oracle) are currently being integrated, with the target of releasing a JVM with a combined code base around the release date of JDK 8.
JRockit was made free and publicly available in May 2011.
Many JRE class files distributed with JRockit exactly replicate those distributed with HotSpot. JRockit overrides class files which relate closely to the JVM, therefore retaining API
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
compatibility while enhancing the performance of the JVM.
The overridden class files include those in the packages:
History
Following the finalization of the acquisition of Sun MicrosystemsSun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
, Oracle
Oracle Corporation
Oracle Corporation is an American multinational computer technology corporation that specializes in developing and marketing hardware systems and enterprise software products – particularly database management systems...
announced in JavaOne 2010
JavaOne
JavaOne is an annual conference inaugurated in 1996 by Sun Microsystems to discuss Java technologies, primarily among Java developers. JavaOne is held in San Francisco, California typically running from Monday to Thursday. Technical sessions on a variety of topics are held during the day. In the...
that the best features of JRockit would be implemented in OpenJDK
OpenJDK
OpenJDK is a free and open source implementation of the Java programming language. It is the result of an effort Sun Microsystems began in 2006...
In May 2011, Oracle announced that JRockit has become free, confirming that they plan to port JRockit features on OpenJDK
OpenJDK
OpenJDK is a free and open source implementation of the Java programming language. It is the result of an effort Sun Microsystems began in 2006...
Oracle JRockit the Definitive Guide
The book "Oracle JRockit - the Definitive Guide" by Marcus Lagergren and Marcus Hirt is the first in-depth book about JVM internals (not just JRockit specific) that was ever published. Not only does it go into details about specific value adds in the JRockit JVM (that are now being ported to the OpenJDK code base), but it also explains runtime internals such as code generation, memory management and thread systems in detail.Performance
Oracle claims that using JRockit can give significant performance gains, but independent benchmarking has not always confirmed this. Server benchmarks on earlier Java Virtual MachineJava Virtual Machine
A Java virtual machine is a virtual machine capable of executing Java bytecode. It is the code execution component of the Java software platform. Sun Microsystems stated that there are over 4.5 billion JVM-enabled devices.-Overview:...
s tend to show that server performance of HotSpot
HotSpot
HotSpot is a Java virtual machine for desktops and servers, maintained and distributed by Oracle Corporation. It features techniques such as just-in-time compilation and adaptive optimization designed to improve performance.-History:...
was better, but that JRockit had a much better scalability.
JRockit Mission Control
JRockit 5.0 R26 bundled a set of tools called JRockit Mission Control.The tools include:
- an interactive Management Console, which visualizes garbage-collectionGarbage collection (computer science)In computer science, garbage collection is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program...
and other performance statistics - a runtime performance profiling tool called Runtime Analyzer
- a memory-analysis tool called Memory Leak Detector
From release R27.3 the tools suite also includes a latency analyzer that graphically visualizes when threads stall due to synchronization, file/network I/O, memory allocation and garbage collection pauses.