Questions & Answers of Deadlock

Question No. 133

A system shares 9 tape drives. The current allocation and maximum requirment of tape drives for three processes are shown below:

Process Current Allocation Maximum Requirment P1 3 7 P2 1 6 P3 3 5

Which of the following best describes current state of the system?

Question No. 130

A system has 6 identical resources and N processes competing for them. Each process can request atmost 2 resources. Which one of the following values of N could lead to a deadlock?

Question No. 245

Consider the following policies for preventing deadlock in a system with mutually exclusive resources.
I. Processes should acquire all their resources at the beginning of execution. If any resource is not available, all resources acquired so far are released.
II. The resources are numbered uniquely, and processes are allowed to request for resources only in increasing resource numbers
III. The resources are numbered uniquely, and processes are allowed to request for resources only in decreasing resource numbers
IV. The resources are numbered uniquely. A process is allowed to request only for a resource with resource number larger than its currently held resources
Which of the above policies can be used for preventing deadlock?

Question No. 41

An operating system uses the Banker’s algorithm for deadlock avoidance when managing the allocation of three resource types X, Y, and Z to three processes P0, P1, and P2. The table given below presents the current system state. Here, the Allocation matrix shows the current number of resources of each type allocated to each process and the Max matrix shows the maximum number of resources of each type required by each process during its execution.

There are 3 units of type X, 2 units of type Y and 2 units of type Z still available. The system is currently in a safe state. Consider the following independent requests for additional resources in the current state:
REQ1: P0 requests 0 units of X, 0 units of Y and 2 units of Z
REQ2: P1 requests 2 units of X, 0 units of Y and 0 units of Z

Which one of the following is TRUE?

Question No. 141

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?

Question No. 46

A system has n resources R0Rn-1, and k processes P0Pk-1. The implementation of the resourcerequest logic of each process Pi. 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?

Question No. 30

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.

Process P1:
t=0: requests 2 units of R2
t=1: requests 1 unit of R3
t=3: requests 2 units of R1
t=5: releases 1 unit of R2
       and 1 unit of R1.
t=7: releases 1 unit of R3
t=8: requests 2 units of R4
t=10: Finishes

Process P2:
t=0: requests 2 units of R3
t=2: requests 1 unit of R4
t=4: requests 1 unit of R1
t=6: releases 1 unit of R3
t=8: Finishes

Process P3:
t=0: requests 1 unit of R4
t=2: requests 2 units of R1
t=5: releases 2 units of R1
t=7: requests 1 unit of R2
t=8: requests 1 unit of R3
t=9: Finishes

Which one of the following statements is TRUE if all three processes run concurrently starting at time t=0?

Question No. 65

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

Question No. 57

A single processor system has three resource types X, Y and Z, which are shared by three processes. There are 5 units of each resource type. Consider the following scenario, where the column alloc denotes the number of units of each resource type allocated to each process, and the column request denotes the number of units of each resource type requested by a process in order to complete execution. Which of these processes will finish LAST?

  alloc request
  X Y Z X Y Z
P0 1 2 1 1 0 3
P1 2 0 1 0 1 2
P2 2 2 1 1 2 0