thrd_yield
From cppreference.com
C
Concurrency support (C11)
Concurrency support library
Threads
Atomic operations
(until C23)
Atomic flags
Memory ordering
Mutual exclusion
Condition variables
Thread-local storage
Defined in header
<threads.h>
void thrd_yield(void);
(since C11)
Provides a hint to the implementation to reschedule the execution of threads, allowing other threads to run.
[edit] Parameters
(none)
[edit] Return value
(none)
[edit] Notes
The exact behavior of this function depends on the implementation, in particular on the mechanics of the OS scheduler in use and the state of the system. For example, a first-in-first-out realtime scheduler (SCHED_FIFO in Linux) would suspend the current thread and put it on the back of the queue of the same-priority threads that are ready to run, and if there are no other threads at the same priority, yield has no effect.
The POSIX equivalent of this function is sched_yield.
[edit] Example
Run this code
#include <stdio.h> #include <time.h> #include <threads.h> // utility function: difference between timespecs in microseconds double usdiff(struct timespec s, struct timespec e) { double sdiff = difftime (e.tv_sec, s.tv_sec); long nsdiff = e.tv_nsec - s.tv_nsec; if(nsdiff < 0) return 1000000*(sdiff-1) + (1000000000L+nsdiff)/1000.0; else return 1000000*(sdiff) + nsdiff/1000.0; } // busy wait while yielding void sleep_100us() { struct timespec start, end; timespec_get(&start, TIME_UTC); do { thrd_yield(); timespec_get(&end, TIME_UTC); } while(usdiff(start, end) < 100.0); } int main() { struct timespec start, end; timespec_get(&start, TIME_UTC); sleep_100us(); timespec_get(&end, TIME_UTC); printf ("Waited for %.3f us\n", usdiff(start, end)); }
Possible output:
Waited for 100.344 us
[edit] References
- C17 standard (ISO/IEC 9899:2018):
- 7.26.5.8 The thrd_yield function (p: 281)
- C11 standard (ISO/IEC 9899:2011):
- 7.26.5.8 The thrd_yield function (p: 385)
[edit] See also
C++ documentation for yield