Performance Analysis and Monitoring with Perf4jCode timing, logging, analyzing and

monitoring tool

Sudhan Kanade

Why do we need Perf4J

• Code works on dev / stage env

• Scalability

• Distributed application

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Analogy: Perf4J to Log4J

• Log4j : System.out.println()

• Perf4J : System.currentTimeMillis()

• Can log similarly to any appenders defined in log4j.

• Can use AspectJ / Spring AOP

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What difference Perf4J makes:

• Without Perf4Jlong start = System.currentTimeMillis();// execute the block of code to be timedlog.info("ms for block n was: " + (System.currentTimeMillis() -

start));

• With Per4JStopWatch stopWatch = new LoggingStopWatch();//... execute code here to be timedstopWatch.stop("example1", "custom message text");

• Allows parsing, analyzing and monitoring the logs.

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Features / Highlights of Perf4J

• A simple stop watch mechanism for concise timing statements.• A command line tool for generating aggregated statistics and

performance graphs from raw log files.• Custom log4j appenders to generate statistics and graphs in a

running application, with java.util.logging and logback support scheduled for subsequent releases.

• The ability to expose performance statistics as JMX attributes, and to send notifications when statistics exceed specified thresholds.

• A @Profiled annotation and a set of custom aspects that allow unobtrusive timing statements when coupled with an AOP framework such as AspectJ or Spring AOP.

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Timing using StopWatch

• Base class : LoggingStopWatch

• SubClass : Log4JStopWatch, CommonsLogStopWatch and Slf4JStopWatch

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Log Parsers: Statistics and Graphs

• Groups stop watch output by tag and by time slice

• Generating detailed statistics information• Time series graphs using the Google Chart API• LogParser reads from standard input thus

allowing it to get output generated in real time.– tail -f performance.log | java -jar perf4j-0.9.8.1.jar

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Sample for LogParser

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Integrating Directly With Log4J

• Set of custom log4j appenders

• Allows Perf4J to expose performance data as attributes on JMX MBeans, and to send JMX notifications.

• Provides graphing appenders that generate performance graphs which can be exposed through a web front-end using a Perf4J graphing servlet.

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sample log4j.xml – perf4j

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sample log4j.xml – log4j and perf4j

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Perf4J appender for JMX:

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@Profiled Annotation

• Reduces the "signal-to-noise" ratio of the code.• Allowing the method body to remain free of

StopWatch code.• Perf4J custom timing aspect can be enabled

with an aspect-oriented programming framework such as AspectJ or Spring AOP

• Minimal overhead.

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@Profiled Annotation - sample

@Profiled(tag = "dynamicTag_{$0}")

public void profiledExample(String tagSuffix) {

... business logic only here

//method body to remain free of StopWatch code

}

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Pitfalls and Best Practices

• Application monitoring - Fail to optimally deliver their intended benefits

• Either too much or not enough where it is required.

• Overhead

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Pitfalls and Best … cont

• When deciding which methods and code blocks to profile, focus on the big fish first.

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Pitfalls and Best … cont

• Perf4J is designed to offload performance analysis to a separate thread or process.

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Pitfalls and Best … cont

• Don’t forget the benefits of performance regression testing

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Pitfalls and Best … cont

• Take advantage of the @Profiled annotation and AspectJ’s load-time weaving to decide which methods should be timed at deployment time.

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Pitfalls and Best … cont

• Don’t forget about parts of your application that execute outside of the JVM

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Future Directions for Perf4J

• Methods to be profiled using a separate configuration file

• To time method executions without access to source code

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