Consider the procedure below for the Producer-Consumer problem which uses semaphores:

semaphore n = 0;
semaphore s = 1;
void producer()
{
    while(true)
    {
     produce();
     semWait(s);
     addToBuffer();
     semSignal(s);
     semSignal(n);
    }
}

void consumer()
{
   while(true)
   {
    semWait(s);
    semWait(n);
    removeFromBuffer();
    semSignal(s);
    consume();
   }
}

Which one of the following is TRUE?

A system has n resources R₀,.....,R_n-1, and k processes P₀,.....,P_k-1. The implementation of the resource request logic of each process P_i, is as follows:

if (i%2==0) {
  if (i < n) request Ri;
  if (i+2 < n) request Ri+2 ;
}
else {
  if (i < n) request Rn-i;
  if (i+2 < n) request Rn-i-2;
}

In which one of the following situations is a deadlock possible?

Consider a system with 4 types of resources R1 (3 units), R2 (2 units), R3 (3 units), R4 (2 units). A non-preemptive resource allocation policy is used. At any given instance, a request is not entertained if it cannot be completely satisfied. Three processes P1, P2, P3 request the sources as follows if executed independently. Which one of the following statements is TRUE if all three processes run concurrently starting at time t = 0?

Which of the following is NOT true of deadlock prevention and deadlock avoidance schemes?