ResumeThread

BOOL ResumeThread( HANDLE hThread );

Parameters

Parameter	Description
hThread	A handle to the thread to be resumed. This handle must have the THREAD_SUSPEND_RESUME access right.

Return value

If the function succeeds, the return value is the thread's previous suspension count. If the function fails, the return value is 0xFFFFFFFF. To get extended error information, call GetLastError.

Remarks

The ResumeThread function increments the suspension count for the specified thread. If the suspension count becomes zero, the thread is transitioned from a suspended state to a runnable state. Otherwise, the thread remains suspended.

A thread's suspension count is a value between 0 and 1024, inclusive. The system limits the suspension count to prevent a thread from being suspended indefinitely.

If ResumeThread succeeds, the return value is the thread's suspension count before the call to ResumeThread. This is useful for applications that suspend a thread multiple times. The application must call ResumeThread the same number of times to resume the thread.

Note: Calling ResumeThread more times than the thread has been suspended can cause unpredictable behavior. Always ensure you track suspension counts to avoid this.

Example

// Create a new thread that starts in a suspended state
HANDLE hThread = CreateThread( NULL, // Default security attributes
0, // Default stack size
MyThreadFunction, // Thread function
NULL, // Parameter to thread function
CREATE_SUSPENDED, // Creation flag
NULL // Thread identifier
);

if (hThread != NULL) {
// Resume the thread
DWORD suspendCount = ResumeThread(hThread);
if (suspendCount == 0xFFFFFFFF) {
// Handle error
printf("Error resuming thread: %lu\n", GetLastError());
} else {
printf("Thread resumed. Previous suspension count: %lu\n", suspendCount);
// The thread will now start execution or continue if it was already running and suspended
}
// Close the thread handle when done
CloseHandle(hThread);
}

Requirements

Attribute	Value
Minimum supported client	Windows 2000 Professional
Minimum supported server	Windows 2000 Server
Header	processthreadsapi.h (include Windows.h)
Library	Kernel32.lib
DLL	Kernel32.dll