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

Explain wait for graph, Explain Wait for Graph a. Use a resource alloca...

Explain Wait for Graph a. Use a resource allocation graph to derive a wait-for graph.  b. Wait-for graph acquired by making an edge from p 1 to p 2 iff p 1 is waiting for

Explain about deadlock detection, Explain about deadlock detection? In ...

Explain about deadlock detection? In deadlock situation, the system must provide An algorithm that verifies the state of the system to verify whether a deadlock has occu

How can application use memory via the win32 api, Q. Explain some of the wa...

Q. Explain some of the ways an application can use memory via the Win32 API. Answer: (1) Virtual memory offers several functions that allow an application to reserve and rele

OS is a resource allocator and control program, why we say OS is a resource...

why we say OS is a resource allocator and control program

What is the use of fork and exec system calls, What is the use of fork and ...

What is the use of fork and exec system calls? Fork is a system call by which a latest process is created. Exec is also a system call, which is used after a fork by one of the

Comparison of disk scheduling algorithms, COMPARISON OF DISK SCHEDULING ALG...

COMPARISON OF DISK SCHEDULING ALGORITHMS Name      Description                  Remarks      (Selection according to requestor)   RSS        Random scheduling     fo

Do ratio analysis of financial statements, Do ratio analysis by comparing t...

Do ratio analysis by comparing the four companies financial statements, analysis and interpretation on the four-basic group : (Refer to attachment A) Liquidity ratio Asset

What is the main advantage of multiprogramming, What is the main advantage ...

What is the main advantage of multiprogramming? Multiprogramming makes efficient use of the CPU by overlapping the demands for the CPU and its I/O devices from various users. I

What are the reasons for process suspension, Q. What are the reasons for pr...

Q. What are the reasons for process suspension? Reasons for process suspension 1.  Swapping 2.  Timing 3.  Interactive user request 4.  Parent process request

Bankers algorithm, p0A B C D A B C D A B C D 2 0 12 2012 1000 1354 0632 ...

p0A B C D A B C D A B C D 2 0 12 2012 1000 1354 0632 0014

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