Program Profiling

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Program Profiling

• GroupMaciej, Reiman, Shaohua, Jason, Corey

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What is it?

• Layman a tool for sampling a program during
  execution so that you can determine where your
  program spends most of its time.
• Formal A profiler is a program that benchmarks
  the execution of one or more pieces of procedural
  code to help the user understand where the time
  is being spent in terms of code execution.

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What it does in one sentence.

• Profiling is used to improve a programs
  performance.

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Questions a Profiler helps Answer

• What lines of code are responsible for the bulk
  of execution time?
• How many times is this looping construct
  executed?
• How many times a method is called and what of
  total program run time it consumes?
• Which approach to coding a block of logic is more
  efficient?

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What a Profiler does

• A profiler can
• measure the elapsed time taken to run source code
• Provide coverage analysis
• Show programs execution history
• How many times a piece of code has been exec.
• Time spent by all exec. of that piece of code
• It is a great way to find where bottlenecks
  occur, so we can make our code more efficient

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What profiling is used for ?

• Profiling is used to help programmers to identify
• which areas of the program are causing sluggish
  bottlenecks.
• which parts of the code are being called the most
  often.
• A Java profiler is used to optimize the
  performance of Java programs, by helping to find
  and tune away expensive parts of them.

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How ?

• JVMPI (JVM Profiler Interface)
• Interface to the JVM where profilers can access
  the state of JVM via an in-process native agent.
• Notifies of events like object allocations,
  method invocations, getCurrentThreadCpuTime()ns.
  
• It scales very badly. (apps having 100s of
  threads and GB sized heaps.)
• Tools most based on JVMPI

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Tools

• JProbe Identify method and line-level
  performance bottlenecks, also detect deadlocks.
• Extensible Java Profiler - Extensible Java
  Profiler (EJP) is a profiling tool for Java with
  a scalable and extensible architecture. Based on
  JVMPI.
• JProfiler
• Open Source Tools
• http//java-source.net/open-source/profilers

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Demo

• JProbe
• EJP (if time permits)

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References

• JProbe (www.quest.com)
• www.webopedia.com
• Javaworld.com
• http//www.dbta.com/in-depth/jan05/schumacher.html
  
• http//cc.borland.com/ccweb.exe/listing?id17681