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2. <Insert Picture Here>
Memory Leak Profiling with NetBeans and HotSpot
Clarence J M Tauro
Senior Curriculum Developer, Oracle ST Java Curriculum

3. Session Agenda
• About the Speaker <Insert Picture Here>
• Different aspects of Performance
• Memory leaks and profiling
• Demo
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4. About the Speaker
• Clarence J M Tauro – clarence.tauro@oracle.com
• Senior Curriculum Developer, Java Curriculum (Oracle ST Curriculum)
• ~7 Years Professional Teaching and Instructional Design Experience
• Masters of Science in Information Technology
• Masters of Technology in Computer Science
• Masters of Philosophy in Computer Science
• Doctor of Philosophy in Computer Science [expected to graduate by August 2012]
• Guest faculty to various Colleges and Universities
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5. Different Aspects of Performance
In this talk we will look
at memory profiling
Memory footprint
Throughput Performance Aspects Scalability
Responsiveness
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6. Memory Leak Profiling: Why and When
• Memory leaks are situations where a reference to allocated objects
remains unintentionally reachable and as a result cannot be garbage
collected.
– Leads to poor application performance
– Can lead to application failure
– Can be hard to diagnose
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7. Garbage Collection – An Overview
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8. Garbage Collection – An Overview
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9. Profiling
• An act of collecting or observing performance data from an operating or
running application.
• Usually more intrusive than monitoring.
• Usually a narrower focus than monitoring.
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10. DEMO – A Servlet with a JavaScript Error
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11. DEMO – Main Class
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12. DEMO – NetBeans Profiler Configuration
I am interested in
Garbage collection
statistics too
Choosing this option
has a lot of additional
overhead
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13. DEMO – Telemetry Overview
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14. DEMO – Live Profiling Results
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15. DEMO – Snapshot of String Class
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16. DEMO – Stack Trace
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17. DEMO – Source of handleScriptException
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18. DEMO – Find Usaged on _errorMessages
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19. DEMO – Source of
____________JavaScript.clearErrorMessages()
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20. DEMO – Find Usages on -----------------------------------------
--------------------JavaScript.clearErrorMessages()
So, who calls the JavaScriptEngineFactory.clearErrorMessages()??
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21. DEMO – Find Usages on
JavaScriptEngineFactory.clearErrorMessages(
)
So, who calls the HttpUnitOptions.clearScriptErrorMessages()??
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22. DEMO – Find Usages on
HttpUnitOptions.clearScriptErrorMessages()
Ahh.. Haa.. You just found the root cause of the memory leak.
The _errorMessages ArrayList is NEVER cleared.. It has only elements added to it.
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23. Farewell to the memory leak!
So, to fix this memory leak, the ArrayList needs to be explicitly cleared.
This is a task for the authors of HttpUnit
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24. Where to go?
• Java Performance Tuning and Optimization Course from
Oracle University
• Java Performance - Charlie Hunt (Author), Binu John (Author) (Expected
August 2011)
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