Thread Management

This section provides information on creating, managing, and synchronizing threads in Windows applications using the Win32 API.

Note: Threads are the basic unit of CPU utilization; they consist of a thread ID, a program counter, a register set, and a stack. Processes can have multiple threads, all sharing the same code, data, and operating system resources.

Thread Creation

Creating a new thread is a fundamental operation for achieving concurrency. The primary function for this purpose is CreateThread.

CreateThread

Creates a new thread within the calling process.

Parameters for CreateThread

Parameter Type Description
lpThreadAttributes LPSECURITY_ATTRIBUTES A pointer to a SECURITY_ATTRIBUTES structure that specifies the security descriptor for the new thread. If this parameter is NULL, the thread gets a default security descriptor.
dwStackSize SIZE_T The initial size, in bytes, of the stack for the new thread. If this parameter is 0, the system uses the default stack size for the new thread.
lpStartAddress LPTHREAD_START_ROUTINE A pointer to the application-defined function of the type TThreadStartRoutine. The thread executes this function until it returns.
lpParameter LPVOID A pointer to a variable to be passed to the new thread.
dwCreationFlags DWORD Flags that control the creation of the thread.
lpThreadId LPDWORD A pointer to a variable that receives the thread identifier of the new thread. 

HANDLE CreateThread(
  [in, optional] LPSECURITY_ATTRIBUTES lpThreadAttributes,
  [in]           SIZE_T                  dwStackSize,
  [in]           LPTHREAD_START_ROUTINE  lpStartAddress,
  [in, optional] LPVOID                  lpParameter,
  [in]           DWORD                   dwCreationFlags,
  [out, optional] LPDWORD                 lpThreadId
);
Tip: For more modern approaches, consider using the C++ Standard Library's std::thread.

Thread Synchronization

When multiple threads access shared resources, synchronization mechanisms are crucial to prevent race conditions and ensure data integrity.

Common Synchronization Objects:

CreateMutex

Creates or opens a mutex object.

WaitForSingleObject

Waits until the specified object is in the signaled state or the time-out interval elapses.

CreateEvent

Creates or opens an event object.

Thread Information

You can retrieve various pieces of information about a thread, such as its ID, state, and priority.

GetCurrentThreadId

Retrieves the thread identifier of the calling thread.

GetThreadPriority

Retrieves the priority of the specified thread.

Thread Priority

Threads can be assigned different priority levels to influence their scheduling. A higher priority thread will preempt a lower priority thread.

SetThreadPriority

Sets the priority of the specified thread. The priority must be within the range from THREAD_PRIORITY_LOWEST to THREAD_PRIORITY_HIGHEST.

Warning: Setting thread priorities too high can lead to system instability or starvation of lower-priority threads. Use with caution.

Thread Priority Levels: