Operating
Systems
CSI3131
Assignment 2
Goal: Practise semaphore usage.
Marks: 50
Description: (Please read the complete assignment document before starting.)
A professor, TA and student are responsible for planting seeds. The student digs the
holes, the professor places a seed in the empty hole, and the TA fills the hole with the
seed. Several synchronization constraints apply to this activity:
1. The professor can plant a seed only if at least one empty hole exists.
2. The TA cannot fill a hole unless at least one unfilled hole exists into which a seed
has been placed.
3. The professor has asked the TA to keep an eye on the student, so the student
cannot get more then MAX holes ahead of the TA. If there are MAX unfilled
holes, the student has to wait.
4. There is only one shovel with which both the student and TA need to dig and fill
the holes, respectively.
Your goal is to simulate the work being completed by the professor, TA, and student.
Using the Java Semaphore Class, complete the Planting.java code provided to
synchronize the student, TA, and Professor threads according to the above
synchronization rules.
In addition to the Semaphore class constructor, you may use the following
Semaphore methods for synchronization: acquire(),
acquireUninterruptible(), tryAcquire(), and release().
Your solution should only use semaphores (using the Semaphore
class), not Java synchronization primitives (i.e. you should not use
synchronized, wait(), and notify()).
The simulation is started by launching “java Planting”.
An example of the output is provided (see log.txt).
To submit your solution:
Submit single file Planting.java, containing your solution. You will get partial marks
for partial solutions. Be sure to include your name and student number at the start of
the file.
