提升企业级Java应用性能：深入JVM与实战策略

需积分: 9 50 浏览量更新于2024-09-08 收藏 1.73MB PDF 举报

"Java性能优化是一个关键主题，尤其对于在企业环境中广泛应用的Java语言而言。自18年前Java成为主导编程语言以来，尽管其地位稳固，但仍存在关于Java性能的认知误区。本篇Refcard旨在帮助开发者通过深入理解JVM（Java虚拟机）内部机制、性能调优原则和最佳实践，来提升各类应用场景中的应用程序性能。首先，JVM Internals是优化的核心，包括类加载(ClassLoading)和垃圾回收(Garbage Collection)。类加载涉及如何高效地加载和管理类，而垃圾回收则关乎内存管理，确保程序运行时资源的有效利用，避免内存泄漏。这两个方面对程序性能有着直接影响。 Java Concurrency是另一个重要的优化领域，因为在高并发环境下，合理设计线程模型和同步机制可以显著提高系统吞吐量和响应速度。了解和应用并发编程模型，如Executor框架和并发工具类，是提升多线程性能的关键。 Application Budgeting强调在有限的资源约束下，如何规划和分配计算预算，比如内存和CPU资源，以确保在满足业务需求的同时保持良好的性能。这需要开发者对资源消耗有清晰的理解，并灵活调整以适应不断变化的需求。此外，工具的使用也是优化过程中的重要一环。Java提供了一系列性能分析和监控工具，如JProfiler、VisualVM和JConsole，这些工具可以帮助开发者识别性能瓶颈，进行诊断和优化。熟练掌握这些工具能极大提升问题解决效率。最后，"最优性能"的定义可能因业务场景而异，但核心目标始终是确保Java程序能够在业务响应时间内完成计算任务，并在高负载情况下稳定、快速地执行其业务功能。通过结合理论知识和实践经验，开发者能够不断改进应用程序的性能表现，从而在激烈的竞争中保持优势。 Java性能优化是一门综合技能，涵盖基础原理到实战技巧，以及对工具的精通运用。理解和实践这些知识，将有助于开发者构建出高效、可扩展的Java应用，满足各种商业环境下的性能需求。"

Java Performance Optimization

BY PIERRE-HUGUES CHARBONNEAU

» JVM Internals

» Class Loading

» Garbage Collection

» Java Concurrency

» Application Budgeting

» Tools

» And more...

JAVA ENTERPRISE EDITION 7

Java is among the most widely used programming languages in the

software development world today. Java applications are used within many

verticals (banking, telecommunications, healthcare, etc.), and in some

cases each vertical suggests a particular set of design optimizations. Many

performance-related best practices are common to applications of all kinds.

The purpose of this Refcard is to help developers improve application

performance in as many business contexts as possible by focusing on the

JVM internals, performance tuning principles and best practices, and how

to make use of available monitoring and troubleshooting tools.

It is possible to dene “optimal performance” in different ways, but the

basic elements are: the ability of a Java program to perform its computing

tasks within the business response time requirements, and the ability

of an application to fulll its business functions under high volume, in

a timely manner, with high reliability and low latency. Sometimes the

numbers themselves become patternized: for some major websites, a

page response time of 500ms maximum per user function is considered

optimal. This Refcard will include target numbers when appropriate,

but in most cases you will need to decide these on your own, based on

business requirements and existing performance benchmarks.

JVM INTERNALS

FOUNDATIONS

CODE COMPILATION AND JIT

Java byte code interpretation is clearly not as fast as native code executed

directly from the host. In order to improve performance, the HotSpot JVM

looks for the busiest areas of byte code and compiles these into native,

more efcient, machine code (adaptive optimization). Such native code is

then stored in the code cache in non-heap memory.

NOTE: most JVM implementations offer ways to disable the JIT compiler

(Djava.compiler=NONE). You should only consider disabling such crucial

optimization in the event of unexpected JIT problems such as JVM crashes.

The following diagram illustrates the Java source code, just-in-time

compilation processes and life cycle.

Get More Refcardz! Visit Refcardz.com

BROUGHT TO YOU IN PARTNERSHIP WITH:

200

JAVA PERFORMANCE OPTIMIZATION

MEMORY SPACES

The HotSpot Java Virtual Machine is composed of the following memory spaces.

MEMORY SPACE DESCRIPTION

Java Heap

Primary storage of the Java program class

instances and arrays.

Permanent Generation

(JDK 1.7 and older)

Metaspace

(JDK 1.8 and later)

Primary storage for the Java class metadata.

NOTE: Starting with Java 8, the PermGen space

is replaced by the Metaspace and using native

memory, similar to the IBM J9 JVM.

Native Heap

(C-Heap)

Native memory storage for the Threads, Stack,

code cache including objects such as MMAP les

and third party native libraries.

CLASS LOADING

Another important feature of Java is its ability to load your compiled Java

classes (bytecode) following the start-up of the JVM. Depending on the

size of your application, the class loading process can be intrusive and

signicantly degrade the performance of your application under high load

following a fresh restart. This short-term penalty can also be explained by

the fact that the internal JIT compiler has to start over its optimization work

following a restart.

It is important to note that several improvements were introduced since

JDK 1.7, such as the ability for the default JDK class loader to better load

classes concurrently.

HOT SPOTS

AREA OF CONCERN RECOMMENDATION

Performance degradation following

a JVM restart.

Avoid deploying an excessive amount

of Java classes to a single application

classloader (ex: very large WAR le).

Free Report

]

5 Important Critical

Capabilities for APM

Gartner Research:

CONTENTS

DZONE.COM

下载后可阅读完整内容，剩余6页未读，立即下载

sinat_28180797

粉丝: 0
资源: 6

提升企业级Java应用性能：深入JVM与实战策略

jdk-8u261-linux-i586.rpm

Java程序性能优化

JAVA代码优化工具

java性能优化介绍

java性能优化详解

大话JAVA性能优化

大话Java性能优化

大话java性能优化

java 性能优化的方向

java性能优化.doc

最新资源