Multithread Programming

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Multithread Programming

• Why Multiple Threads?
• Processes vs. Threads
• Threads vs. Functions (Processes vs. Programs)
• Thread States (Unstarted, Running, WaitSleepJoin,
  SuspendRequested, Suspended, AbortRequested,
  Aborted, StopRequested, Stopped)
• Thread Priority (Highest, AboveNormal, Normal,
  BelowNormal, Lowest)
• Thread Scheduling
• Thread Synchronization

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execution trace
concurrent I/O operation
interrupt handler (routine)
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• Take the previous GUI lectures and Proj 3 as an
  example,
• Form1 and myDialog.
• Multitasking the program? (Can we work on two
  additions simultaneously?)
• (of course, if we invoke MyDialog in a
  non-blocked way)
• Multithreaded programming
• Split a program into multiple segments (with
  beginning and ending points)
• Run some of them concurrently
• On a single processor (CPU) machine, time-sharing
  by multiple threads
• True for multi-core, Hyper-Threading

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Multithreading on a Uniprocessorinterleaving of
multiple threads within multiple processes
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Execution states of a thread
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Using Threads in C/CLI

• Method One
• Create a task
• Create a thread to associate with the task
• Start the thread
• Wait for a thread to end
• Runs in foreground or background
• Create an instance of thread. Use a delegate
  ParameterizedThreadStart to place the method to
  be the thread
• Start() the thread
• A thread can Sleep()
• Thread Sleep(2000) // 2000
  milliseconds
• One thread waits for another thread to finish
  before continuing, Join()

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Using Threads in C/CLI

• Method Two thread pool
• Create a task
• Queue the task to the thread pool
• Thread pool is system-managed, easy to use.
• Run in background, so the main needs to remain
  alive
• Add to the pool ThreadPoolQueueUserWorkItem()
  //true if added
• Takes WaitCallback() delegate (so to run your
  thread task)
• Takes an Object handle (so to pass info to the
  thread task)

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Examples