Terminating a Thread

A thread executes until one of the following events occurs:

• The thread calls the ExitThread function.
• Any thread of the process calls the ExitProcess function.
• The thread function returns.
• Any thread calls the TerminateThread function with a handle to the thread.
• Any thread calls the TerminateProcess function with a handle to the process.

The GetExitCodeThread function returns the termination status of a thread. While a thread is executing, its termination status is STILL_ACTIVE. When a thread terminates, its termination status changes from STILL_ACTIVE to the exit code of the thread. The exit code is either the value specified in the call to ExitThread, ExitProcess, TerminateThread, or TerminateProcess, or the value returned by the thread function.

When a thread terminates, the state of the thread object changes to signaled, releasing any other threads that had been waiting for the thread to terminate. For more about synchronization, see Synchronizing Execution of Multiple Threads.

If a thread is terminated by ExitThread, the system calls the entry-point function of each attached DLL with a value indicating that the thread is detaching from the DLL (unless you call the DisableThreadLibraryCalls function). If a thread is terminated by ExitProcess, the DLL entry-point functions are invoked once, to indicate that the process is detaching. DLLs are not notified when a thread is terminated by TerminateThread or TerminateProcess. For more information about DLLs, see Dynamic-Link Libraries.

Warning  The TerminateThread and TerminateProcess functions should be used only in extreme circumstances, since they do not allow threads to clean up, do not notify attached DLLs, and do not free the initial stack. The following steps provide a better solution:

• Create an event object using the CreateEvent function.
• Create the threads.
• Each thread monitors the event state by calling the WaitForSingleObject function. Use a wait time-out interval of zero.
• Each thread terminates its own execution when the event is set to the signaled state (WaitForSingleObject returns WAIT_OBJECT_0).