Windows Threading

Colin RobyJaewook Kim

P PP P P P

MicrokernelMulti-Processor Computing

System

Threads Interface

Hardware

Operating System

ProcessProcessor ThreadP

Applications

Programming paradigms

OS, Process, and Thread

Legacy Window Threading Model (Co-operative Threading)

Co-operative ThreadingUsed by Old 16-bit Window PlatformThread continue execution until

Thread terminatesExecutes instruction causing wait (e.g., IO)Thread volunteering to stop (invoking yield or sleep)

Architecture for Cooperative Threading Model

Advantages & Disadvantages

Threading Models from Windows NT to 2003

Windows NT~2003 OSPreemptive multi-processing operating system

The OS schedules the CPU timeThe application can be preempted by OS scheduler

Windows ThreadThe unit of execution (in UNIX, Process is the unit)Implements the one-to-one mappingEach thread contains

A thread idRegister setSeparate user and kernel stacksPrivate data storage area

The register set, stacks, and private storage area are known as the context of the threadsThe primary data structures of a thread include:

ETHREAD (executive thread block)KTHREAD (kernel thread block)TEB (thread environment block)

Windows Thread TypesSingle Threading

Each process is started with a single thread

Multiple ThreadingA thread can be created by Win32 Pthread or Windows Thread API

Hyper ThreadingSimultaneous multithreading technology on the Pentium 4 microarchitecture by IntelSupported by Windows 2000 or more

Windows Threading Models

Win32 Threading ModelWin32 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)

STA & MTA

COM Object

COM Object

Thread Synchronization

Win32 Threading Example

Creating a Threadstart_servers( ) {

HANDLE thread; DWORD id; int i;for (i=0; i<nr_of_server_threads; i++)

thread = CreateThread(0, // security attributes0, // default # of stack pages allocated(LPTHREAD_START_ROUTINE) server, // start

routine(LPVOID)0, // argument0, // creation flags&id); // thread ID

...}

DWORD WINAPI server(void *arg) {while(TRUE)

// get and handle requestreturn(0);

}

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 in={r_in, l_out}, out={l_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);

}

TerminationExitThread((DWORD) value);

return((DWORD) value);

WaitForSingleObject(thread, timeOutValue);

GetExitCodeThread(thread, &value);

CloseHandle(thread);

Threading Model for Multicore System

Additional Slides

21

Basic concepts used for CPU and resource management

Processes and Threads (1)

22

Relationship between jobs, processes, threads, and fibers

Processes and Threads (2)

23Some of Win32 calls for managing processes, threads and

fibers

Job, Process, Thread & Fiber Mgmt. API Calls

Windows Threading

One-to-one modelOne-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.

Fibers vs. ThreadsFibers 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 interfaceConvertThreadToFiber() 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.

Stack PagesHANDLE thread;

thread = CreateThread(0, 16*1024, startroutine, arg, 0, &id);

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