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Using and Extending Memory Analyzer into Uncharted Waters

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Presentation given at EclipseCon 2011 in Santa Clara, CA, about using and extending the Eclipse Memory Analyzer (MAT). Session abstract at …

Presentation given at EclipseCon 2011 in Santa Clara, CA, about using and extending the Eclipse Memory Analyzer (MAT). Session abstract at http://www.eclipsecon.org/2011/sessions/?page=sessions&id=2184

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  • Hprof is the file that MAT plugins are able to load and display memory reports Retained heap is the memory kept alive by a class X
  • CompositeHeapEditorPane is the base class for the pages inside MAT report OQLPane is a page that shows memory usage and have an edit field to filter classes in the report using a syntax similar to SQL (called OQL – object query language) MotodevPane (see picture) generates the filter selecting the Android application package (e.g.: the statement with “com.a.*” for the user).
  • It would be interesting to mention that in the 2-week time, we also p rovided methods to pull MAT files from phone/emulator integrated into our Device Manager view
  • Transcript

    • 1. Vladimir Pavlov Dimitar Giormov SAP Labs Bulgaria Using and Extending Memory Analyzer into Uncharted Waters Memory Analyzer
    • 2.
      • Introduction
        • The Headaches
        • Eclipse Memory Analyzer
      • Extending Eclipse Memory Analyzer
        • API and Extension Points
        • JRuby Case
        • Android Apps Case
      • Q & A
      © SAP 2010 / Page
    • 3.
      • Memory leaks
        • Hard to debug and find the root cause
        • Eventually lead to OOM errors
        •  Brings your system down
        •  Often not reproducible
      • Thread issues
        • Deadlocks
        • Exhausted threads
        • Waiting for an external resource – e.g. DB connection
        •  Application does not respond
        •  Whole system hangs
      THE HEADACHES © SAP 2010 / Page
    • 4.
      • Eclipse Memory Analyzer (MAT) is…
        • Java heap analyzer
        • Helps find memory leaks and reduce memory consumption
        • UI and programmatic access to data in the heap dumps
        • Multi-Gigabyte Java Heap Dumps Are Nothing to Fear Now
        • Soooo much faster than other tools, e.g. jhat
        • Very little memory “overhead” for processing heap dumps (again – cf. jhat)
        • Supports Sun, SAP, HP, IBM JDKs 1.4.2 and above
        • Automatic problem recognition
        • Could also process thread dumps and correlate data to provide additional details
        • Initial contribution from SAP, joined by IBM
        • Highly extensible
      ECLIPSE MEMORY ANALYZER © SAP 2010 / Page Memory Analyzer
    • 5.  
    • 6.
      • Why extend MAT?
        • To save time doing the same thing repeatedly
        • To help others use the same technique as you
        • To do things not possible from the GUI
        • To build in application or domain specific logic
      • How to extend MAT?
        • MAT provides a set of Eclipse extension points
        • User writes an extension plug-in
        • MAT provides an API for reading data from a heap dump
      EXTENDING MAT © SAP 2010 / Page
    • 7.
      • Isnapshot
        • Represents a heap dump
        • Methods for reading classes and objects, getting sizes, GC roots, referenced objects, etc.
      • Object model
        • IClass
        • IObject
          • IInstance
            • IClassLoader
          • IArray
            • IPrimitiveArray
            • IObjectArray
      PROGRAMMATIC ACCESS TO A SNAPSHOT © SAP 2010 / Page
    • 8.
      • Name Resolver
        • Used to give meaningful descriptions of objects
        • Similar to a toString() method
        • Extension point: org.eclipse.mat.api.nameResolver
      • Query
        • Used for exploring dumps or detailed analysis
        • Result in the form of a table, tree, histogram, pie chart, free text...
        • Integrated into MAT’s menus
        • “ Collaboration” of queries
        • Extension point: org.eclipse.mat.report.query
      • Request Resolver
        • Used to provide details about what a thread was doing
        • Contributes to Leak Suspects report
        • Extension point: org.eclipse.mat.api.requestResolver
      EXTENSION POINTS © SAP 2010 / Page
    • 9.
      • Parser – for new heap dump types and VMs, such as for Jikes RVM
      • Trigger Heap Dump – org.eclipse.mat.api.heapDumpProvider
        • For new VM types
      • Reports – org.eclipse.mat.report.report
        • HTML results of queries – also used for batch mode
      • Thread Resolver – additional thread data such as native stacks
      • Ticket Resolver – can identify appropriate routing for problems
        • Based on classes and class loaders of problematic objects
      • Rendering – org.eclipse.mat.api.renderer
        • Additional to HTML and CSV
      • Annotations used as filters and for configuration
      EXTENSION POINTS (CONTD.) © SAP 2010 / Page
    • 10.
      • Ruby is…
        • Dynamic scripting language
        • Object-oriented
        • Focus on simplicity and productivity
        • Elegant syntax, natural to read and easy to write
      • JRuby is…
        • 100% Java implementation of the Ruby programming language
        • Interpreter running atop the JVM
        • Generating Java bytecode (JIT compilation mode)
        • Tight integration with Java
      RUBY AND JRUBY © SAP 2010 / Page
    • 11.
      • Adding JRuby into the picture…
      THE HEADACHES – AGGRAVATED © SAP 2010 / Page
    • 12.  
    • 13.
      • What were the goals
        • Identify memory leaks (critical when talking about embedded systems due to hardware restrictions)
        • Filter memory usage by classes belonging to the users’ application
        • Simpler workflow: developers start analyzing by classes they already know (not Android system classes)
      • Why MAT was chosen
        • The MAT perspective provides views to analyze application status, identify leaks, and so on, given an HPROF file
        • Reports are easy to navigate and provide information about retained heap
        • It is Eclipse based
        • Android supports the creation and extraction of HPROF files
      MAT INTEGRATION WITH MOTODEV STUDIO
    • 14.
      • Implemented an Extension
        • Extension point used: org.eclipse.mat.ui
        • Added a new page extending CompositeHeapEditorPane
      • Created MotodevPane based on OQLPane class
      WORK DONE ON MAT
    • 15.
      • The integration of MOTODEV Studio, Google DDMS and Eclipse MAT worked very well.
      • Used the org.eclipse.mat.ui extension point, which was well-documented.
      • It took about 2 weeks of one developer to study the project, implement and test the solution.
      OVERALL EXPERIENCE
    • 16.
      • Eclipse Memory Analyzer provides:
      • Powerful and efficient memory analysis features out-of-the-box
      • API for extracting data from a heap dump
      • Application or domain specific analysis can be added as extensions
      SUMMARY © SAP 2010 / Page
    • 17. RESOURCES © SAP 2010 / Page
    • 18. THANK YOU! in: vpavlov t: @giormov Memory Analyzer