A deep understanding of Java virtual machines into Java

Java Technology System

Java programming language, Java Virtual machine, Java API Class library collectively known as JDK
The Java API Class library in Java SE API subset and Java Virtual machine collectively known as the JRE

Java History

April 1991 the predecessor of the Java language-oak language launch
May 1995 Oak renamed Java and released 1.0 version of Write Once,run Anywhere
January 1996 JDK 1.0 release provides Java Virtual machine implementation ( Sun Classic VM ), applets, AWT
February 1997 JDK 1.1 release provides the jar file format, JDBC, JavaBeans, RMI
December 1998 JDK1.2 release Java split in the following three directions, virtual Machine Additions HotSpot VM and Exact VM
Java ME 支持Java程序运行在移动终端的平台 
Java SE 支持面向桌面级应用的Java平台 
Java EE 支持使用多层架构的企业应用的Java平台
May 2000 JDK 1.3 release default virtual machine changed HotSpot VM to
February 2002 JDK 1.4 release provides regular expressions, exception chains, NIO, XML parsers, and XSLT converters
September 2004 JDK 1.5 release provides syntax features such as auto-unboxing, generics, dynamic annotations, enumerations, variable-length parameters, traversal loops (foreach), and provides java.util.concurrent and contract packages to improve the Java memory model
December 2006 JDK 1.6 release provides dynamic language support, a compilation API, and a micro HTTP Server API to make a lot of improvements inside the Java Virtual machine
February 2009 JDK 1.7 release provides a new G1 collector, enhanced support for non-Java language calls, and upgraded class loading schemas
April 2009 Oracle Announces Acquisition of Sun Company for $7.4 billion

Java Virtual machine history Sun classic/exact VMs

• Sun Classic is the world's first commercial Java Virtual machine, this virtual machine can only be executed in a pure interpreter code, not work with the compiler, so the efficiency of execution and traditional C + + programs have a large gap;
• To improve the efficiency of the classic VM, Sun released the exact VM virtual machine at JDK 1.2, with level two even though the compiler, the compiler and interpreter are mixed, and accurate memory management. Although the exact VM is a lot more advanced than the classic VM, it only exists for a short time and is replaced by the hotspot VM.

Sun HotSpot VMs

The hotspot VM was acquired by Sun in 1997, and Longview Technologies it has inherited the benefits of Sun's two virtual machines, as well as many of its own new strengths, such as hotspot Code detection technology.

BEA jrockit/ibm J9 VM

• JRockit VMS, once known as "The fastest Java virtual machine in the world," Bea has developed into a highly optimized virtual machine for server hardware and service-side scenarios, with little focus on program startup speed and no parser implementations.
• The J9 VM is a virtual machine extension from the IBM Ottawa Lab named Smalltalk, a multi-purpose virtual machine designed to be fully considered from server-to-desktop applications to embedded.

Azul vm/bea Liquid VM

• Azul VM is a Java virtual machine that AUZL systems has improved on a hotspot basis, running on a proprietary hardware Vega system
• Liquid VM is now the JRockit VE, is the BEA developed virtualized version of JRockit VMs running on their own hypervisor systems

other VMS

A deep understanding of Java virtual machines into Java