ciabatta/test/test_threads.c

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#include <stdio.h>
#include <threads.h>
#include <stdatomic.h>
atomic_int acnt;
int cnt;
int f(void* thr_data)
{
for(int n = 0; n < 100000; ++n) {
atomic_fetch_add_explicit(&acnt, 1, memory_order_relaxed); // atomic
++cnt; // undefined behavior, in practice some updates missed
}
return 0;
}
int main(void)
{
thrd_t thr[10];
for(int n = 0; n < 10; ++n)
thrd_create(&thr[n], f, NULL);
for(int n = 0; n < 10; ++n)
thrd_join(thr[n], NULL);
printf("The atomic counter is %d\n", acnt);
printf("The non-atomic counter is %d\n", cnt);
}