© 2014 IBM Corporation

SHOW104: Practical Java

Mark Myers, London Developer Coop Julian Robichaux, panagenda

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Performance Analysis and Troubleshooting

Code Optimization

Make your code work first, then worry about speed – You always want working code to fall back on

Is it fast enough? Leave it alone.

An elegant solution that is slightly slower is often better than an ugly solution that is slightly faster

Making code shorter doesn’t make it faster

Keep the code readable and easy to troubleshoot

Don’t assume you know where the bottleneck is

“We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil”

- Donald Knuth

Static Code Analyzers

FindBugs is a great tool for finding potential problems

Bugs grouped by categories – Scariest – Scary – Troubling

Also subcategories like “Correctness”, “Security”, “Performance”, and “Dodgy Code”

New cloud option for development teams – Rank bugs, assign fixes

http://findbugs.sourceforge.net

http://www.cs.umd.edu/~pugh/MistakesThatMatter.pdf

FindBugs

FindBugs

Debugging, Logging, and Unit Testing

Mark and Julian did a 2-hour presentation on debugging, logging, and unit testing at Lotusphere 2012

– Please see the slides at: – http://londondevelopercoop.com/ldc.nsf/pages/goodies

Highlights: – How to add unit testing to Java code in DDE – How to add unit testing to JavaScript code – Debugging Java agents on Notes clients and Domino servers – Debugging Java classes used by XPages – Tips for using Java logging

Common Bottlenecks

Some other guy’s server

Slow database queries

Memory issues – Leaks (less common than you’d think) – Too much cached information

• Especially large objects, strings, XML – Strong references

Loading and unloading resources

Non-lazy initialization of objects

Slow or broken network connection

Simulating Poor Network Connections

http://www.charlesproxy.com

http://jagt.github.io/clumsy

Network Link Conditioner (OSX) – XCode > Open Developer Tool > More Developer Tools

Analyzing Java Memory Usage

Used for: – Tracking down memory leaks – Finding high-memory-use objects (and arrays) – Finding objects that are unexpectedly still in memory

IBM Heap Analyzer – https://www.ibm.com/developerworks/community/alphaworks/tech/heapanalyzer – http://www-01.ibm.com/support/docview.wss?uid=swg27006624&aid=1

YourKit Java profiling app – http://yourkit.com – http://notesin9.com/index.php/2012/11/29/notesin9-091-xpages-memory-profiling-part-1

Eclipse Memory Analysis Tool – http://www.eclipse.org/mat/downloads.php – http://lazynotesguy.net/blog/2013/08/30/wheres-my-memory-gone-peeking-inside-jvms-

heap-part-1-installation – http://lazynotesguy.net/blog/2013/10/04/peeking-inside-jvms-heap-part-2-usage

Generating Heap Dumps with Notes/Domino

Domino XPages – tell http xsp heapdump – XPages Toolbox ( http://www.openntf.org/p/XPages%20Toolbox )

Notes Client (Expeditor) – notes\framework\rcp\rcplauncher.exe -com.ibm.rcp.core.logger#dump heap -dumps heapdump – writes to notes\data\workspace\logs\heapdump.###.phd by default – You can also do a core (thread) dump with:

• notes\framework\rcp\rcplauncher.exe -com.ibm.rcp.core.logger#dump threads -dumps javacore

Directly from Java – com.ibm.jvm.Dump.HeapDump(); – writes to notes\framework\heapdump.###.phd when run from an agent

Access Connect Online to complete your session surveys using any: – Web or mobile browser – Connect Online kiosk onsite

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Mark Myers London Developer Coop mark@energywins.co.uk Twitter: @stickfight

Julian Robichaux panagenda jrobichaux@panagenda.com Twitter: @jrobichaux

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Acknowledgements and Disclaimers

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