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NUPOINT TECHNOLOGY INC.MANAGER OF R&D DEPT.

LIN, WEICHENG

Optimize Your Java Code By Tools

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Agenda

Why to Optimize Your Code?

Introduction

Optimize by OptimizeIt

Conclusions

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Why to Optimize Your Code?

Why coding?

Why do your program need more execution time or developing time than that of others’?

Do you agree that Programming is an ART?

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Introduction

How to write a good program? Suitable language

C++, Java, Perl, Scheme, … Good algorithm

You need to learn Algorithm, OS, … Good implementation

You need not only a good brain but a good tool

Bad implementation Allocate too much memory Instantiate too many objects Bad programmatic logic …

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Introduction (Cont.)

There are several tools for optimization use: OptimizeIt, …

Functions of Optimization Tools Profiling Code Coverage Checking Thread Debugging Progress Tracking Request Analyzing

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Optimize by OptimizeIt

The goal of the optimization

A quick introduction to the application

Application architecture

Integrating JBuilder and OptimizeIt

Optimizing your first project

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The Goal of the Optimization

Using JBuilder and OptimizeIt to solve performance problems with an email agent A user with 4000 Messages per day

Before the performance tuning Several minutes

After the performance tuning < 10 seconds

Improvement Less execution time Less required memory

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A Quick Introduction to the Application

1. Spam filteringIt deletes spam from a user's mailbox using a variety of spam-filtering rules

2. Forwarding of desirable email messages to a pagerA user can control which email messages should be forwarded from their inbox to their pager

3. Mail server-independenceThe Email Agent works with any email server that supports the POP-3 or IMAP standards

4. Platform-independenceThe Email Agent can run on any computer platform that supports Java, making it very flexible to install

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Application Scenario

Scenario Currently, only a user, with 4,000 messages About 1,000 spam messages Running every five minutes In the need of handling more users

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Application Architecture

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Basic Algorithm of the Email Agent

1. Application startup. 2. Initialize logger. 3. Read mail server connection properties. 4. Read properties for sending a summary report to the user. 5. Initialize internal lists from configuration files. 6. Create and populate the EmailAgent. 7. Connect to the mailbox. 8. Remove spam from the current folder.

1. Get the message list from the inbox. 2. Determine the UIDs of these messages. 3. Get a list of messages that have already been examined already. 4. While only looking at new messages:

1. One at a time, review each message to determine whether or not it is spam. 1. If the message matches an ``allow'' file rule, let it pass through. 2. Otherwise, test the From, Reply-To, and Subject fields, as well as message attachments.

2. If a message matches a notification criteria, send a message to my pager.

9. Close the mailbox and store. 2. Send me summary information about what actions were taken.

Be care of your for-loop!Be care of your for-loop!

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Basic Configuration

Configuring the application allow.from allow.subject allow.contents reject.from reject.subject reject.contents

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Integrating JBuilder and OptimizeIt

Installation

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Integrating JBuilder and OptimizeIt (Cont.)

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Optimizing Your First Project

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Finding the Performance Problems

Java Performance Tuning'' by Jack Shirazi

1. Measure the performance of the application, using tools, and/or by instrumenting the code.

2. Identify the location of any bottlenecks. 3. Think of a hypothesis for the cause of the bottleneck. 4. Consider any factors that might refute your hypothesis. 5. Create a test to isolate the factor identified by the

hypothesis. 6. Test the hypothesis. 7. Alter the application to reduce the bottleneck. 8. Test that the alteration improves the performance. 9. Repeat from step 1.

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Finding the Performance Problems (Cont.)

Simplified version of the process 1. Instrument your code and find the major bottlenecks,

using the best tools available 2. Fix the bottlenecks that are causing the biggest

problems, don't worry about the others. If you can't fix it, avoid it

3. If performance is now acceptable, celebrate. If not, repeat from step 1

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Finding the Performance Problems (Cont.)

Fix the bottlenecks that are causing the biggest problems and don't worry about the others Simplified analysis example

examineContents() - 70% extractContents() - 20% parseAttachment() - 10%

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The First Run: An Example of How to Use Avoidance Therapy

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Drill Down Your Programmatic Flow

Using Contents needs a lotof time

1. Put this line in the last2. It will be run when needed

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The Second Run

Built in JDK Built in JDK

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The Third Run: Problems with Regular Expressions

aMatcher.find() wastes too much time

aMatcher.find() wastes too much time

indexOf is faster

indexOf is faster

Change the order!

Change the order!

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9,956 ms9,956 ms

aMatcher.find() is still slow, we use aMatcher.matches()aMatcher.find() is still slow, we use aMatcher.matches()

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9,548 ms9,548 ms

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Getting Harder Now

9,548 ms9,548 ms

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Getting Harder Now (Cont.)

9,353 ms9,353 ms

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Conclusions

Reducing the application runtime from over 52 seconds down to about 9.4 seconds

You really need a optimization tool, don’t you?

Now, do you agree that Programming is an ART?

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Thanks!