CSE3221 (Winter 2008) Assignment One

Deadline: Feb 4^th (12:00 noon)

You have to work individually. You are not allowed to view or exchange documents with your peers. We treat all sorts of cheating very seriously. Do not copy code from anywhere, even as a `template''. No late submission will be accepted. You are required to program in your PRISM account. Your work will be graded based on: i) correctness of programming logic; ii) clarity of your code and your coding style; iii) whether your code follows the specification. It is your responsibility to explain clearly every detail you do in the code with appropriate comments to avoid any possible confusion in marking.

You are required to write two C programs to process some data sets. The programs will be able to calculate the median[1] value for each data set and print out results for all data sets according to the following required format. Each data set is stored in a file which consists of some integer numbers between 0 and 100. The file format is that all data samples in this data set are separated by whitespace in the file. As example, we have posted three data sets on the course Web: dataset1, dataset2, dataset3, for your reference. However, your program should be able to process any number of data sets which are passed through from the command line.

• Write your first C program, called process.c, to do the calculation concurrently with multiple processes. The program first reads file names of all data sets from the command line. For each data set, it creates a child process. Each child process first reads all data from the file, and calculates the median and the sample count of the data set, and sends the median and the count to the main process via a Unix pipe. The main program will print out all these results (including both median and count) along with the file name of the data set to the standard output. If you have more than one data set, the outputs should be printed out according to descending order of median values. The output of one data set occupies one line as follows:

Filename1 median1 count1

Filename2 median2 count2

…

• Write another Pthread C program, called thread.c, to repeat the above calculation concurrently with multiple threads. The program creates a thread to process each data set. Each thread calculates the median and the count for each data set and passes them to the main program. The main program waits for all threads to finish and print out all results following the exactly same output format as above.

Your programs should compile as follows:

cc –o prs process.c

cc –o thr thread.c –lpthread

And the programs should run as follows (all datasets are provided as command line arguments):

prs dataset1 dataset2 dataset3 …

thr dataset1 dataset2 dataset3 …

What to submit?

Submit two C programs using the following commands from your PRISM account:

submit 3221 a1 process.c

submit 3221 a1 thread.c

No hardcopy is needed to submit for this assignment.

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[1] Median value is defined as the number in a data set which separates the higher half of the data set from the lower half.