The first part goes into the Java1.java technology systemSun's officially defined Java technology System includes several components:
Java Program Set Language
Java virtual machines on a variety of hardware platforms
class file format
Today began the actual combat Java Virtual Machine two: "Virtual machine working mode."Total of 5 Series
"Heap overflow processing" in one of the actual Java virtual machines
support) virtual machine process of the class information, memory, garbage Collection, JIT compilation and other running data, in the absence of a GUI, only provides a plain text console environment on the server, it will be the operating period to locate virtual machine performance issues of the preferred tool.Jstat
) virtual machine process of the class information, memory, garbage Collection, JIT compilation and other running data, in the absence of a GUI, only provides a plain text console environment on the server, it will be the operating period to locate virtual machine performance issues of the preferred tool.Jstat command
Java Virtual Machine: runtime volume pool, Java Virtual Machine volume pool1. Introduction to the runtime frequent pool
Runtime Constant Pool, which is part of the method area. In addition to the description of the version, field,
In the Java virtual machine specification, there are two exceptions to this area of the virtual machine stack :(1) If the thread requests a stack depth greater than the virtual machine
Since the work, the more written code, the program is increasingly bloated, less efficient, for me such a pursuit of the perfect programmer, this is absolutely not allowed, so in addition to constantly optimize the program structure, memory optimization and performance tuning has become my usual "trick."
To perform memory optimization and performance tuning on Java programs, do not understand the internal principle of the
Virtual machine class loading mechanismThe virtual machine loads the data of the description class from the class file into the memory, verifies the data, parses and initializes it, and finally forms the Java type that can be used directly by the
Google launched the Android SDK at the end of 2007 as an important feature of the Android system, and the Dalvik virtual machine was the first to come into view. Its efficient use of memory and its high performance on low-speed CPUs are truly impressive. Relies on the underlying POSIX-compliant operating system, which can simply complete process isolation and thread management. Each Android app will have a
Dalvik virtual machines exist in the Android system, the JVM is a Java virtual machine, both are virtual machines, what is the difference between them? This article compares the two to tell the difference between them.1. Definition:Dalvik
Time of class loading
When you encounter the 4 bytecode directives of new, getstatic, putstatic, or invokestatic, if the class has not been initialized, you need to trigger its initialization first. The most common Java scenario for generating these 4 instructions is when instantiating an object using the New keyword, reading or setting a static field of a class (except for a static variable that is final decorated, has placed the result into
I. PrefaceThe execution engine of the physical machine is run directly on the physical hardware such as CPU, operating system, instruction set, but for the virtual machine, his execution engine is implemented by himself. The execution engine has a uniform appearance (Java Virtual
Introduction??This chapter is about the memory area of the Java virtual machine can be divided into several parts, the book can be divided into five parts: heap, Stack, program counter, method area, local method stack??Where the heap contains an instance of the object??And often said the basic data type, and the object reference is stored in the stack, in fact, i
Understanding of the Java Virtual machine stackThe virtual machine stack is the stack memory we know, and the stack memory is unique to the thread. The reference type stored in the local variable table in the stack memory is simply the memory address of the storage object. T
Android Dalvik Virtual Machine (difference from Java Virtual Machine and brief execution principle), androiddalvik
The location of the Dalvik virtual machine in the Android framework
the difference between a Java virtual machine and a Dalvik virtual machine:Java Virtual machineDalvik virtual MachinesJava virtual machines are stack -based. Stack-based machines must u
??This phrase feels like the nature of the GC .??????1. Procedure Counter (program Counter Register)??A program counter is a small amount of memory space that acts as a line number indicator of the bytecode that is being executed by the current thread . The bytecode interpreter works by changing the value of this counter to select the next byte-code instruction to execute, and the basic functions such as branching, looping, jumping, exception handling, thread recovery, and so on, need to rely on
Jps-java process StatusJPS is similar to the Linux PS command for viewing processes.JPS Name: Jps-java Virtual Machine Process Status Toolcommand usage: JPS [Options] [HostID]Options: Command option to control the output formatHostID: Specify a specific host, which can be an IP address and a domain name, or specify a s
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