volatile

main.c

// gcc main.c -O2 -lpthread
#include <pthread.h>

void *threadMain( void *ptr ) {
	*(int*)ptr = 0;
}

int main() {
	int exitThread = 1;	// volatile
	pthread_t h;
	pthread_create( &h, NULL, threadMain, (void*)&exitThread );
	while( exitThread )
		;
}