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Optimize with a SATA RAID Storage Solution
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Simply speaking, a JVM is the software module that executes Java application bytecode and translates the bytecode into hardware- and operating system-specific instructions. By doing so, the JVM enables Java programs to be executed in different environments from where they were first written, without requiring any changes to the original application code. Java's portability is key to its popularity as an enterprise application language: developers don't have to rewrite application code for every platform because the JVM handles the translation and platform-optimization.
A JVM basically is a virtual execution environment acting as a machine for bytecode instructions, while assigning execution tasks and performing memory operations through interaction with underlying layers.
A JVM also takes care of dynamic resource management for running Java applications. This means it handles allocating and de-allocating memory, maintaining a consistent thread model on each platform, and organizing the executable instructions in a way that is suited for the CPU architecture where the application is executed. The JVM frees the programmer from keeping track of references between objects and knowing how long they should be kept in the system. It also frees us from having to decide exactly when to issue explicit instructions to free up memory -- an acknowledged pain point of non-dynamic programming languages like C.
You could think about the JVM as a specialized operating system for Java; its job is to manage the runtime environment for Java applications. A JVM basically is a virtual execution environment acting as a machine for bytecode instructions, while assigning execution tasks and performing memory operations through interaction with underlying layers.
There's a lot more to write about JVM internals and performance optimization. As foundation for upcoming articles in this series, I'll conclude with an overview of JVM components. This brief tour will be especially helpful for developers new to the JVM, and should prime your appetite for more in-depth discussions later in the series.
A compiler takes one language as an input and produces an executable language as an output. A Java compiler has two main tasks:
Compilers are either static or dynamic. An example of a static compiler is javac. It takes Java code as input and translates it into bytecode -- a language that is executable by the Java virtual machine.
Static compilers interpret the input code once and the output executable is in the form that will be used when the program executes. Because
the input is static you will always see the same outcome. Only when you make changes to your original source and recompile
will you see a different result.