Due: Tuesday, March 10, End of day (whatever you consider the end of day...)
Reading: Chapter 7 and 8 of Programming Erlang
You are again welcome to work with others for this assignment, but each
person must turn in their own code and graphs.
Overview
For this assignment, you will create a small concurrent program that
benchmarks process creation and message passing while exploring
N-version programming.
The benchmark should create C client processes and 3 server processes.
As in N-Version programming, the 3 server processes compute the same
function, but in slightly different ways. The client does not
completely trust the results returned by any one server: therefore,
the client asks all 3 servers to compute the result and uses majority
voting to determine the correct result.
The sophisticated function that each server computes for this
assignment is the multiplication of two arguments. Think of 3
slightly different ways you can write a function that multiplies two
numbers together and have each of the 3 servers use a different
approach.
Make sure you define errors reasonably. For example, if the 3 servers
all give different results, then the client should throw an error.
The C client processes should all be asking the servers to compute the
functions concurrently; there is no coordination across the C clients.
Each of the clients should repeat the sending, adding, receiving of results, and
voting M times. C and M should be command-line arguments to your
program.
Evaluate the Impact of M and C
Time how long your benchmark program takes as a function of C and M.
(Don't do any I/O to slow things down, please.)
Pick some interesting values for C and M. Vary them (independently is
fine) and measure the time for the program. Graph the results
(remember to label your axes). Be sure you report the details of the
machine you are running on (e.g., Erlang version, OS version, CPU
details, and amount of memory).
Turning in your assignment
Please bring to class a print out of your graph (just the graphs, not
the code anymore).
Please copy your code to the directory
~cs739-1/Spring09/handin/[login]/P4 where [login] is
your CS login name.
Again, comment your code enough that someone can follow what you did.
We won't grade you on elegance, or simplicity, or creativity, or
anything other than functionality and comments. If different students
come up with wildly different solutions, we'll try to share some of the
different approaches.
You might find it interesting to look at the write-ups others have
done for the ring benchmark specified as Problem 2 in 8.11 of the
book. If you google "Erlang ring benchmark" you can look at other
people's code and timing results from now until the end of the semester...
