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Windows Threading. Colin Roby Jaewook Kim. Threads Interface. Microkernel. Multi-Processor Computing System. . . P. P. P. P. P. P. P. Processor. Process. Thread. OS, Process, and Thread. Applications. Programming paradigms. Operating System. Hardware.
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Windows Threading Colin Roby Jaewook Kim
Threads Interface Microkernel Multi-Processor Computing System P P P P P P P Processor Process Thread OS, Process, and Thread Applications Programming paradigms Operating System Hardware
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)
Windows NT~2003 OS • Preemptive multi-processing operating system • The OS schedules the CPU time • The application can be preempted by OS scheduler
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)
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
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)
STA & MTA COM Object COM Object
Creating a Thread start_servers( ) { HANDLE thread; DWORD id; int i; for (i=0; i<nr_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); }
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); }
Termination ExitThread((DWORD) value); return((DWORD) value); WaitForSingleObject(thread, timeOutValue); GetExitCodeThread(thread, &value); CloseHandle(thread);
Processes and Threads (1) Basic concepts used for CPU and resource management
Processes and Threads (2) Relationship between jobs, processes, threads, and fibers
Job, Process, Thread & Fiber Mgmt. API Calls Some of Win32 calls for managing processes, threads and fibers
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.
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.
Stack Pages HANDLE thread; thread = CreateThread(0, 16*1024, startroutine, arg, 0, &id);