I. Project Organization
This project will study the coordination of multiple threads using semaphores.
You should do the following pieces to complete your project. Each piece is explained below:
• Design 40 points
• Code 25 points
• Output 25 points
• Summary 10 points
The design should consist of two things: (1) a list of every semaphore, its purpose, and its initial value,
and (2) pseudocode for each function. The pseudocode should be similar to the pseudocode shown in the
textbook for the barbershop problem. Every wait and signal call must be included in the pseudocode.
Your code should be nicely formatted with plenty of comments. The code should be easy to read,
properly indented, employ good naming standards, good structure, and should correctly implement the
design. Your code should match your pseudocode.
Output will be graded by running your program.
The summary section should discuss your simulation, any difficulties encountered, what was learned,
and results. It should be at least one page in length.
II. Project Description
This project must target a Unix platform and execute properly on our cs1 or csgrads1 Linux server.
The project must be written in C, C++, or Java.
If using C or C++, you must use POSIX pthreads and semaphores.
If using Java, you must use Java Threads and Java Semaphores (java.util.concurrent.Semaphore).
You should not use the “synchronized” keyword in Java.
You should not use any Java classes that have built-in mutual exclusion.
Any mechanisms for thread coordination other than the semaphore are not allowed.
Doctor’s Office Simulation
This project will simulate a visit to the doctor’s office. It is similar to the “barbershop” example in the
The clinic to be simulated has doctors, each of which has their own nurse. Each doctor has an office of his
or her own in which to visit patients. Patients will enter the clinic to see a doctor, which should be
randomly assigned. Initially, a patient enters the waiting room and waits to register with the receptionist.
Once registered, the patient sits in the waiting room until the nurse calls. The receptionist lets the nurse
know a patient is waiting. The nurse directs the patient to the doctor’s office and tells the doctor that a
patient is waiting. The doctor visits the patient and listens to the patient’s symptoms. The doctor advises
the patient on the action to take. The patient then leaves.
Receptionist – one thread
Doctor – one thread each, maximum of 3 doctors
Nurse – one per doctor thread, identifier of doctor and corresponding nurse should match
Patient – one thread each, up to 30 patients
The program should receive the number of doctors and patients as command-line inputs.
1) A thread should sleep 1 second at each step the thread prints an activity.
2) All mutual exclusion and coordination must be achieved with semaphores.
3) A thread may not use sleeping as a means of coordination.
4) Busy waiting (polling) is not allowed.
5) Mutual exclusion should be kept to a minimum to allow the most concurrency.
6) Each thread should only print its own activities. The patient threads prints patient actions and the
doctor threads prints doctor actions, etc.
7) Your output must include the same information and the same set of steps as the sample output.
1) Each step of each task of each thread should be printed to the screen with identifying numbers so it
is clear which threads are involved.
2) Begin by printing the number of patients, nurses, and doctors in this run.
3) Thread activity output sample. Your output should contain the same set of steps per thread:
Run with 3 patients, 3 nurses, 3 doctors
Patient 0 enters waiting room, waits for receptionist
Receptionist registers patient 0
Patient 0 leaves receptionist and sits in waiting room
Patient 2 enters waiting room, waits for receptionist
Nurse 0 takes patient 0 to doctor’s office
Receptionist registers patient 2
Patient 0 enters doctor 0’s office
Patient 2 leaves receptionist and sits in waiting room
Patient 1 enters waiting room, waits for receptionist
Nurse 2 takes patient 2 to doctor’s office
Receptionist registers patient 1
Patient 2 enters doctor 2’s office
Doctor 0 listens to symptoms from patient 0
Patient 1 leaves receptionist and sits in waiting room
Patient 0 receives advice from doctor 0
Doctor 2 listens to symptoms from patient 2
Patient 2 receives advice from doctor 2
Nurse 1 takes patient 1 to doctor’s office
Patient 1 enters doctor 1’s office
Doctor 1 listens to symptoms from patient 1
Patient 1 receives advice from doctor 1
Patient 0 leaves
Patient 2 leaves
Patient 1 leaves
III. Project Guidelines
Your final project should work correctly on cs1 or csgrads1.
Submit your project on eLearning. Include in your submission the following files:
1) ‘design.xxx’ where xxx is doc, docx, or pdf.
2) ‘summary.xxx’ where xxx is doc, docx, or pdf.
3) ‘project2.c’, ‘project2.cpp’, or ‘Project2.java’ along with any other source files.
4) ‘readme.txt’ containing:
a) the complete command line used to compile your program
b) the complete command line used to run your program
c) any other details the TA should know
Partial or Missing Submissions
It is your responsibility to upload all of the right files on time. It is recommended that you double-check
the files you upload to make sure they are the right ones. Once the deadline passes, changes to the
submission are not accepted without a late penalty.
This is an individual project. All work must be your own. Comparison software may be used to compare
the work of all students. Similar work will be reported to the Office of Judicial Affairs for investigation.
The written portions will be graded subjectively based on completeness and quality. The code will be
graded based on points allocated for each key part of the processing as determined by the instructor. The
output will be graded based on expected results.
The web has many articles on threads and there are books available on threads. The course website also
contains example source code.