SuspendThread function
Suspends a thread.
Syntax
DWORD SuspendThread(
HANDLE hThread
);
Parameters
Return value
Remarks
Example
| Parameter | Description |
|---|---|
hThread | Handle to the thread to be suspended. The handle must have THREAD_SUSPEND_RESUME access. |
If the function succeeds, the return value is the thread's previous suspend count.
If the function fails, the return value is (DWORD)-1. To get extended error information, call GetLastError.
- A thread can be suspended multiple times. Each call increments the suspend count. The thread resumes execution only when the suspend count reaches zero.
- Suspending a thread does not guarantee that it will not execute any code before the suspend takes effect. Use synchronization primitives for precise control.
- Do not suspend a thread that holds a critical section or a mutex, as it can cause deadlocks.
- Suspending a thread in a different process requires that the calling process have the
SE_DEBUG_NAMEprivilege.
Below is a simple example that creates a thread, suspends it for a few seconds, and then resumes it.
#include <windows.h>
#include <stdio.h>
DWORD WINAPI ThreadFunc(LPVOID lpParam) {
for (int i = 0; i < 5; ++i) {
printf("Thread running: %d\n", i);
Sleep(1000);
}
return 0;
}
int main(void) {
HANDLE hThread = CreateThread(NULL, 0, ThreadFunc, NULL, 0, NULL);
if (!hThread) { printf("CreateThread failed\n"); return 1; }
Sleep(1500); // Let the thread run a bit
printf("Suspending thread...\n");
SuspendThread(hThread);
Sleep(3000); // Thread is suspended
printf("Resuming thread...\n");
ResumeThread(hThread);
WaitForSingleObject(hThread, INFINITE);
CloseHandle(hThread);
return 0;
}