Java Performance Tuning and Optimization Student Guide

Transcription

1 Java Performance Tuning and Optimization Student Guide D69518GC10 Edition 1.0 June 2011 D73450

2 Disclaimer This document contains proprietary information and is protected by copyright and other intellectual property laws. You may copy and print this document solely for your own use in an Oracle training course. The document may not be modified or altered in any way. Except where your use constitutes "fair use" under copyright law, you may not use, share, download, upload, copy, print, display, perform, reproduce, publish, license, post, transmit, or distribute this document in whole or in part without the express authorization of Oracle. The information contained in this document is subject to change without notice. If you find any problems in the document, please report them in writing to: Oracle University, 500 Oracle Parkway, Redwood Shores, California USA. This document is not warranted to be error-free. Restricted Rights Notice If this documentation is delivered to the United States Government or anyone using the documentation on behalf of the United States Government, the following notice is applicable: U.S. GOVERNMENT RIGHTS The U.S. Government s rights to use, modify, reproduce, release, perform, display, or disclose these training materials are restricted by the terms of the applicable Oracle license agreement and/or the applicable U.S. Government contract. Trademark Notice Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners. Authors Clarence Tauro, Michael Williams Technical Contributors and Reviewers Charlie Hunt, Staffan Friberg This book was published using: Oracle Tutor

3 Table of Contents Introduction Introduction Course Goal Course Objectives Class Introductions Audience Prerequisites Course Map Course Topics Course Schedule Course Environment Additional Resources JVM and Performance Overview JVM and Performance Overview Objectives JVM Overview Java Programming Language HotSpot JVM: Architecture Key HotSpot JVM Components What Is Performance? Memory Footprint Startup Time Scalability Application Scalability Responsiveness Throughput Performance Focus for This Course Performance Issues Covered in This Course Performance Issues Not Covered in This Course Performance Methodology Performance Monitoring Performance Profiling Performance Tuning Typical Development Process Application Performance Process Summary Java Performance Resources Additional Resources Monitoring Operating System Performance Monitoring Operating System Performance Objectives Why Are We Monitoring? Monitoring CPU Usage Overview CPU Monitoring Performance Indicators Voluntary Context Switching (VCX) Involuntary Context Switching (ICX) Tools For Monitoring CPU Usage i

4 CPU Usage: vmstat CPU Usage: mpstat CPU Usage: prstat CPU Usage: prstat -m CPU Usage: prstat -Lm CPU Monitoring: Solaris - cpubar Map Lightweight Processes to Java Threads Monitoring Network I/O Overview Network I/O: Using tcptop Network I/O: Using nicstat Monitoring Disk I/O Overview Disk I/O: iotop Monitoring Virtual Memory: Overview Virtual Memory Tools Virtual Memory: vmstat Virtual Memory: Swapping Example Monitoring Virtual Memory: cpubar Virtual Memory: Fixing the Swapping Problem Monitoring Processes Overview Process Monitoring Tools Processes: prstat-lm Processes: mpstat Monitoring the Kernel Kernel: vmstat Kernel: mpstat Kernel: prstat-lm Summary Monitoring the JVM Monitoring the JVM Objectives What to Monitor HotSpot GC Basics The Young GC Process: Part The Young GC Process: Part The Young GC Process: Part The Young GC Process: Part The Young GC Process: Part The Young GC Process: Summary Young Generation Recap Tenured (old) Generation Permanent Generation Tools for Monitoring GC Using -verbose:gc Additional -verbose:gc Print Options Using -XX:+PrintGCDetails Printing Pause Time Using jps Using jstat Using jconsole ii

5 Using VisualVM Using VisualGC Using GCHisto Monitoring JIT Compilation Using XX:+PrintCompilation What Is the.hotspot_compiler File? Using.hotspot_compiler File Focusing on Throughput Focusing on Responsiveness Summary Performance Profiling Performance Profiling Objectives Tools for Profiling Java Applications NetBeans and NetBeans Profiler NetBeans Oracle Solaris Studio jmap and jhat Profiling Tips CPU Profiling: Why and When CPU Profiling: Strategies CPU Profiling Entire Application CPU Profiling a Portion of the Application Heap Profiling: Why and When Heap Profiling: Strategies Heap Profiling: jmap/jhat Heap Profiling: jmap/jhat Strategies Memory Leak Profiling: Why and When Memory Leaks Profiling Tips: Tools Memory Leaks: NetBeans/VisualVM Strategies Memory Leaks: jmap/jhat Strategies Lock-Contention Profiling: Overview How to Reduce Lock Contention Biased Locking Inlining Effect Identifying Anti-Patterns Anti-Patterns in Heap Profile Anti-Patterns in Heap Profiles Anti-Patterns in Method Profiles Summary Garbage Collection Schemes Garbage Collection Schemes Objectives Garbage Collection Basics Normal Deletion Deletion with Compacting Generational Garbage Collection Why Generational GC? Generational Garbage Collection: Major Spaces iii

6 Features of Young Generational Space Features of Old Generation Space Generational Garbage Collection Garbage Collection Notations Generational Garbage Collection: Young Collection GC Performance Metric Choices of Garbage Collecting Algorithms Serial versus Parallel Stop the World Versus Concurrent Compacting Versus Non-Compacting Versus Copying Types of GC Collectors Serial Collector Serial Collector on Young Generation: Before Serial Collector on Young Generation: After Serial Collector on Old Generation Parallel Collector: Throughput Matters! Parallel Collector on Young Generation Parallel Compacting Collector Concurrent Mark-Sweep (CMS) Collector CMS Collector Phases CMS Collector on Old Generation Garbage Collectors: Comparisons Ergonomics: What It Does Ergonomics Summary Garbage Collection Tuning Garbage Collection Tuning Objectives Garbage Collectors: Recap Garbage Collection: Myth Garbage Collectors: Sizing Java Heap Spaces Garbage Collectors: Sizing Spaces Garbage Collectors: The Choices Garbage Collectors: Serial Collector Garbage Collectors: Throughput Collector Garbage Collectors: Concurrent Collector Serial Collector Versus Parallel Collector Parallel Collector Versus CMS Collector Garbage Collectors: Permanent Generation GC Output: Using Serial Collector GC Output: Using Throughput Collector GC Output: Using Concurrent Collector Concurrent Collector: Losing the Race Garbage Collectors: PrintGCStats Garbage Collectors: GCHisto Summary Language-Level Concerns and Garbage Collection Language-Level Concerns and Garbage Collection Objectives iv

7 Object Allocation: Best Practices Object Allocation: Working with Large Objects Garbage Collectors: Explicit GC Data Structure Sizing Garbage Collectors: Reference Objects Reference Objects, Illustration (1/2) Reference Objects: Illustration (2/2) Reference Objects: Soft Reference Reference Objects: Weak Reference Reference Objects: Phantom Reference Garbage Collectors: Soft References Memory Leaks Garbage Collectors: Finalizers Finalizers Versus Destructors Summary Performance Tuning at the Language Level Performance Tuning at the Language Level Objectives Strings: An Introduction Compile Time Versus Runtime Strings How JVM Works with Strings Optimization by Interning Strings String Versus StringBuffer Versus StringBuilder StringBuffer Versus StringBuilder (in Nanoseconds) Execution of "+" Operator in String (in Milliseconds) Exception Handling and Performance Exception Handling and Performance (in Nanoseconds) Primitives Versus Objects Primitives Versus Objects [Benchmark Results] Prefer Reusing Objects Thread Synchronization Collections Performance of Java Collections Benchmark Results Copying Entire Array: Use System.arrayCopy Tuning Java I/O Performance Speeding Up I/O Speeding Up I/O: Approach Speeding Up I/O: Approach Speeding Up I/O: Approach Speeding Up I/O: Performance Benchmarking Buffering Reading/Writing Text Files Formatting Costs Formatting Costs: Use MessageFormat Class Formatting Costs: Benchmarking Random Access Compression Tokenization v

8 Serialization Summary Appendix A: Monitoring Linux Performance Monitoring Linux Performance Objectives Tools For Monitoring Linux CPU Usage: Linux - vmstat CPU Usage: Linux mpstat CPU Usage: pidstat Linux Gnome System Monitor Monitoring Network I/O: Using nicstat Monitoring Disk I/O: pidstat Example Kernel Monitoring Using: pidstat Summary Appendix B Appendix B Objectives Java HotSpot VM Options Categories of Java HotSpot VM Options Useful -XX Options vi