ExitThread

ExitThread is a Windows API function in kernel32.dll that terminates the calling thread. It ends the current thread’s execution and assigns the thread’s exit code to the value provided as the dwExitCode parameter. The exit code can later be retrieved by GetExitCodeThread using the thread’s handle. ExitThread affects only the calling thread; the process and other threads continue to run.

Prototype and behavior: ExitThread(DWORD dwExitCode) terminates the calling thread immediately and unwinds the thread’s execution context. It does not terminate the entire process, and other threads remain unaffected. The thread’s exit code is stored and available to querying code that waits on or monitors the thread.

Usage considerations: If the thread was created with the C run-time library (CRT) support, via _beginthread or _beginthreadex, it is recommended to terminate the thread with _endthread or _endthreadex to allow the CRT to perform proper cleanup, such as TLS destructor calls. Using ExitThread in CRT-managed threads can lead to resource leaks or improper cleanup. For threads created with CreateThread that do not rely on the CRT, ExitThread is appropriate.

Retrieving exit status: After a thread terminates, its exit code can be obtained by calling GetExitCodeThread with the thread’s handle. If a thread terminates abnormally or via an unhandled exception, the exit code may reflect that condition.

Alternatives and cautions: TerminateThread can forcibly stop a thread from another thread and may bypass cleanup, so it is generally unsafe and not recommended unless there is no other option. ExitThread should be used when a thread can terminate gracefully with proper resource cleanup.