CS 3733 Operating Systems, Fall 2010 Assignment 4 Comments

This assignment was graded out of 40 points.
Parts 1 and 2 were 5 pints each. Parts 3 and 4 were 15 points each.

• The grades were not good on this assignment.
  Only 6 of 15 students got 30 points or more.
• Do not output color files to a monochrome printer. In some cases, part of your code was invisible.
• Use a single staple in the upper left corner.
  Do not print in the upper left corner under the staple.
• If the parent waits for the child, before computing, the program will not run in parallel.
• What is wrong with the following implementation:
  

       for (i=atoi(argv[1];i<=atoi(argv[2];i++) {
       ...
       }
  

• If you have all processes (including the original parent) write to a pipe, and have the original parent read from the pipe only when it is done, you can get a deadlock as follows:
  • Process A writes to the pipe, and fills it up.
  • Process A blocks, waiting for the pipe to empty.
  • Process B, the original parent, tries to write to the pipe and blocks because the pipe if full.
  • Process B never gets to the code in which it reads from the pipe.
  • No process can write to the pipe.
  Even if the original parent doesn't write to the pipe, you can lose concurrency if a process fills the pipe before the parent gets to the code in which it reads from the pipe.

  One solution is to create another process whose only purpose it to read from the pipe.