Example of producer consumer - semaphore, Operating System

Assignment Help:

Now let's implement bounded producer-consumer with semaphores, a Coke machine which is initially empty:

semaphore sem_mutex = 1 // binary semaphore for mutual exclusion, 1==unlocked

semaphore slots_left = N
semaphore cokes_left = 0
producer()
down(slots_left)
down(sem_mutex)
insert Coke into machine
up(cokes_left)
up(sem_mutex)
consumer()
down(cokes_left)
down(sem_mutex)
buy Coke
up(slots_left)
up(sem_mutex)

Note that the down(slots left) needs to go before the down(sem mutex), and similarly for down(cokes left) and down(sem mutex), because otherwise the system can end up waiting forever. For example, imagine an empty machine with the consumer arriving ?rst, and calling down(sem mutex) before down(cokes left).

In some sense, the consumer calling down(cokes left) is a reservation to get a Coke in the future. Even if there are no Cokes currently in the machine, the consumer is reserving a claim for a future Cokewith this action. Similarly, the producer calling down(slots left) is a reservation to insert a new Coke in the future.


Related Discussions:- Example of producer consumer - semaphore

What are privileged instructions, What are privileged instructions? Som...

What are privileged instructions? Some of the machine instructions that may cause harm to a system are designated as privileged instructions. The hardware permits the privilege

What is process migration, Question: (a) Describe blocking and non-bloc...

Question: (a) Describe blocking and non-blocking types of inter-process communication. What is easier to implement and why? Discuss their relative advantages and disadvantage

Draw and r chart and an x-bar chart, Thermostats are subjected to rigorous ...

Thermostats are subjected to rigorous testing before they are shipped to air conditioning technicians around the world. Results from the last five samples are shown in the table. D

Explain resource allocation graph, RESOURCE ALLOCATION GRAPH When a pro...

RESOURCE ALLOCATION GRAPH When a process Pi wishes an instance of resource type Rj, a request edge is inserted in the resource allocation graph. When this request is able to be

Parent process: why not finishing and how to make finish, #include #inclu...

#include #include #include #include #include int main(void) { int pchan[2], pid, rval, cvar; char buf[20]; if (pipe(pchan) == -1){

Bag of tasks, The producer-consumermodel above has a standard human analogy...

The producer-consumermodel above has a standard human analogy of an assembly line. Humans have specialized skills, however, whereas threads running the same program do not need to

Making the transition to client - server programming, Making the Transition...

Making the Transition to Client - Server Programming Making the transition to client - server programming is a significant effort. Client - server applications must be designed

Why is rotational optimization no longer consequently useful, UNIX systems ...

UNIX systems utilized to use disk-layout optimizations based on the rotation position of disk data however modern implementations including Linux simply optimize for sequential dat

Producer - consumer synchronization, This assignment is based on Programmin...

This assignment is based on Programming Project 6.40 in Silbershatz. Implement the ProducerXConsumer program according to the instructions for Project 6.40 for both Linux and Win32

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd