The GetThreadPriority function returns the priority value for the specified thread. This value, together with the priority class of the thread's process, determines the thread's base-priority level.
int GetThreadPriority(
HANDLE hThread // handle to thread
);
Windows NT: The handle must have THREAD_QUERY_INFORMATION access.
If the function succeeds, the return value is the thread's priority level.
If the function fails, the return value is THREAD_PRIORITY_ERROR_RETURN. To get extended error information, call GetLastError.
The thread's priority level is one of the following values:
| Priority | Meaning |
|---|---|
| THREAD_PRIORITY_ABOVE_NORMAL | |
| Indicates 1 point above normal priority for the priority class. | |
| THREAD_PRIORITY_BELOW_NORMAL | |
| Indicates 1 point below normal priority for the priority class. | |
| THREAD_PRIORITY_HIGHEST | |
| Indicates 2 points above normal priority for the priority class. | |
| THREAD_PRIORITY_IDLE | |
| Indicates a base-priority level of 1 for IDLE_PRIORITY_CLASS, NORMAL_PRIORITY_CLASS, or HIGH_PRIORITY_CLASS processes, and a base-priority level of 16 for REALTIME_PRIORITY_CLASS processes. | |
| THREAD_PRIORITY_LOWEST | |
| Indicates 2 points below normal priority for the priority class. | |
| THREAD_PRIORITY_NORMAL | |
| Indicates normal priority for the priority class. | |
| THREAD_PRIORITY_TIME_CRITICAL | |
| Indicates a base-priority level of 15 for IDLE_PRIORITY_CLASS, NORMAL_PRIORITY_CLASS, or HIGH_PRIORITY_CLASS processes, and a base-priority level of 31 for REALTIME_PRIORITY_CLASS processes. | |
Every thread has a base-priority level determined by the thread's priority value and the priority class of its process. The operating system uses the base-priority level of all executable threads to determine which thread gets the next slice of CPU time. Threads are scheduled in a round-robin fashion at each priority level, and only when there are no executable threads at a higher level will scheduling of threads at a lower level take place.
For a table that shows the base-priority levels for each combination of priority class and thread priority value, refer to the SetPriorityClass function.
Windows CE: The thread's priority level is one of the following values:
Indicates 2 points above normal priority.
THREAD_PRIORITY_NORMAL
Indicates normal priority.
THREAD_PRIORITY_LOWEST
Indicates 2 points below normal priority.
THREAD_PRIORITY_ABOVE_IDLE
Indicates 3 points below normal priority.
Windows CE does not support priority classes. The order in which threads are scheduled is determined only by their thread priorities.
When manipulating priorities, ensure that a high-priority thread does not consume all of the available CPU time. A thread with a priority level of THREAD_PRIORITY_TIME_CRITICAL will execute until it explicitly yields processing to other threads. Processing of these threads is not yielded to other threads with the THREAD_PRIORITY_TIME_CRITICAL priority level. Such a thread can interfere with the normal operation of the operating system if the thread doesn't explicitly yield processing quickly.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winbase.h.
Import Library: Use kernel32.lib.
Processes and Threads Overview, Process and Thread Functions, GetPriorityClass, SetPriorityClass, SetThreadPriority