Mutexes

Can be accessed by reading shared variable

create new list element element
set e.value = X
read list and list.p_next
set e.pointer = list.p_next
set list.p_next = e

Mutex, Lock(mutex), blocked_threads

List<int> my_list;
Mutex m;
void safe_insert(int i){
	Lock(m){
		my_list.insert(i);
	}
}

for i=0..10
	producers[i] = fork(safe_insert, NULL)
consumer = fork(print_and_clear, my_list)

Lock(m){
	list->insert(my_thread_id)
} // unlock

Lock(m){
	if my_list.full -> print; clear up to limit of elements of list
	else -> release lock and try again (later)
}

Condition Variable

Lock(m){
	while (my_list.not_full())
Wait(m. list_full);
	m_list.print_and_remove_all();
}

Lock(m){
	my_list.insert(my_thread_id);
	if my_list.full()
		Signal(list_full);
}