Windows Threading

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Windows Threading

• Colin Roby
• Jaewook Kim

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OS, Process, and Thread
Applications
Programming paradigms
Operating System
Hardware
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Legacy Window Threading Model (Co-operative
Threading)
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Co-operative Threading

• Used by Old 16-bit Window Platform
• Thread continue execution until
• Thread terminates
• Executes instruction causing wait (e.g., IO)
• Thread volunteering to stop (invoking yield or
  sleep)

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Architecture for Cooperative Threading Model
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Advantages Disadvantages
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Threading Models from Windows NT to 2003
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Windows NT2003 OS

• Preemptive multi-processing operating system
• The OS schedules the CPU time
• The application can be preempted by OS scheduler

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Windows Thread

• The unit of execution (in UNIX, Process is the
  unit)
• Implements the one-to-one mapping
• Each thread contains
• A thread id
• Register set
• Separate user and kernel stacks
• Private data storage area
• The register set, stacks, and private storage
  area are known as the context of the threads
• The primary data structures of a thread include
• ETHREAD (executive thread block)
• KTHREAD (kernel thread block)
• TEB (thread environment block)

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Windows Thread Types

• Single Threading
• Each process is started with a single thread
• Multiple Threading
• A thread can be created by Win32 Pthread or
  Windows Thread API
• Hyper Threading
• Simultaneous multithreading technology on the
  Pentium 4 microarchitecture by Intel
• Supported by Windows 2000 or more

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Windows Threading Models

• Win32 Threading Model
• Win32 Pthread or Windows Thread API
• COM (Component Object Model) Threading Model
• Single Threaded Apartments (STA)
• Multi Threaded Apartments (MTA)
• Both Threading Model (STA or MTA)

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STA MTA
COM Object
COM Object
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Thread Synchronization
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Win32 Threading Example
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Creating a Thread

• start_servers( )
• HANDLE thread DWORD id int i
• for (i0 iltnr_of_server_threads i)
• thread CreateThread(0, // security attributes
• 0, // default of stack pages allocated
• (LPTHREAD_START_ROUTINE) server, // start
  routine
• (LPVOID)0, // argument
• 0, // creation flags
• id) // thread ID
• ...
• DWORD WINAPI server(void arg)
• while(TRUE)
• // get and handle request
• return(0)

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When is it done?

• rlogind(int r_in, int r_out, int l_in, int l_out)
  
• HANDLE in_thread, out_thread
• two_ints_t inr_in, l_out, outl_in, r_out
• in_thread CreateThread(0, 0, incoming, in, 0,
  id)
• out_thread CreateThread(0, 0, outgoing, out,
  0, id)
• WaitForSingleObject(in_thread, INFINITE)
• CloseHandle(in_thread)
• WaitForSingleObject(out_thread, INFINITE)
• CloseHandle(out_thread)

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Termination

• ExitThread((DWORD) value)
• return((DWORD) value)
• WaitForSingleObject(thread, timeOutValue)
• GetExitCodeThread(thread, value)
• CloseHandle(thread)

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Threading Model for Multicore System
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Additional Slides
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Processes and Threads (1)

• Basic concepts used for CPU and resource
  management

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Processes and Threads (2)

• Relationship between jobs, processes, threads,
  and fibers

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Job, Process, Thread Fiber Mgmt. API Calls

• Some of Win32 calls for managing processes,
  threads and fibers

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Windows Threading
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One-to-one model

• One-to-one model
• A process in Windows XP is inert it executes
  nothing
• A process simply owns a 4GB address space that
  contains code and data for an application.
• In addition, a process owns other resources, such
  as files, memory allocations, and threads.
• Every process in Windows XP has a primary thread.
• Threads in Windows XP are kernel-level threads.
• Per-thread data structures
• Total user/kernel time, kernel stack,
  thread-scheduling info.,
• Thread-local storage array, thread environment
  block (TEB),
• List of objects thread is waiting on,
  synchronization info. Etc.

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Fibers vs. Threads

• Fibers vs. Threads
• Fibers are often called lightweight threads.
• They allow an application to schedule its own
  threads of execution.
• Fibers are invisible to the kernel.
• They are implemented in user-mode in Kernel32.dll
• Fibers interface
• ConvertThreadToFiber() converts a thread to a
  running fiber.
• A new fiber can be created using CreateFiber().
• The new fiber runs until it exits or until it
  calls SwitchToFiber().
• Fibers provide a functionality of the
  many-to-many model.

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Stack Pages

• HANDLE thread
• thread CreateThread(0, 161024, startroutine,
  arg, 0, id)

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Client Script Callbacks