CSCI 3323 (Principles of Operating Systems), Fall 2013:
Homework 3
- Credit:
- 10 points.
Be sure you have read Chapter 2, sections 2.1 through 2.3 and 2.5
Answer the following questions. You may write out your answers by
hand or using a word processor or other program, but please submit
hard copy, either in class or in my mailbox in the department office.
- (5 points)
Solve the dining philosophers problem with monitors
rather than semaphores. (Do this yourself, though,
rather than looking for a solution online or in another book!)
- (5 points)
Restrooms are usually designated as men-only or women-only,
but this requires having two restrooms if everyone is
to be accommodated.
A less expensive approach consistent with cultural norms
in the U.S. would be to have one restroom with a sign on
the door that indicates its current state -- empty,
in use by at least one woman, or in use by at least one
man. If it is empty, either a man or a women may enter;
if it is occupied, a person of the same sex may enter,
but a person of the opposite sex must wait until it is
empty.
Write pseudocode for four functions to implement this
approach:
woman_enter, man_enter,
woman_leave, and man_leave,
to be used by the following pseudocode:
/* woman process */
while (TRUE) {
woman_enter();
use_restroom();
woman_leave();
do_other_stuff();
}
/* man process */
while (TRUE) {
man_enter();
use_restroom();
man_leave();
do_other_stuff();
}
You can use any of the synchronization mechanisms we
have talked about (shared variables, semaphores, monitors,
or even message passing).
Do the following programming problems. You will end up with at
least one code file per problem.
Submit your program source (and any other needed files)
by sending mail to
bmassing@cs.trinity.edu,
with each file as an attachment.
Please use a subject line that mentions the course number and
the assignment (e.g., ``csci 3323 homework 3'').
You can develop your programs on any system that provides the
needed functionality, but I will test them on one of the department's
Linux machines, so you should probably make sure they work
in that environment before turning them in.
- (Optional -- up to 5 extra-credit points)
Write a program to test your solution to
either problem 1 or
problem 2.
If you want to do this using C and POSIX threads, you could start
with the code for the programming problem in Homework 2.
Or you could write in Java and use
its monitor-based synchronization (synchronized methods/blocks
plus wait, notify, and notifyAll)
and/or features of the java.util.concurrent library
package (which has, among many other things, a Semaphore library class).
You can find some simple examples of multithreaded Java programs
on the ``Sample programs'' page for my parallel programming class:
http://www.cs.trinity.edu/~bmassing/CS3366/SamplePrograms/.
The bounded buffer example may be useful if you want to
use monitor-based synchronization.
Berna Massingill
2013-10-17