Description
Learning Objectives:
The primary learning objectives of this assignment include learning to use concurrent programming
abstractions including POSIX threading. Additional learning objectives include being able to reason about the
concurrent execution of threads and use of synchronization abstractions.
Homework:
Write a multi-threaded console application to perform [M×N] × [N×P] matrix multiplication to produce an
[M×P] matrix using POSIX threads (pthreads). The program’s name should be “matrix-multiply”.
Specifications
1. You must create threads using the POSIX pthreads APIs.
2. You must perform matrix multiplication on two input matrices [A] x [B]. For example:
Let A be a [3×2] matrix:
Let B be [2×3] matrix:
Then, [A] × [B] = [C], which is the [3×3] matrix:
3. Each element (C11, C12 ,…., C33) of the resultant matrix C must be calculated by a separate thread. For
example the value of C11 needs to be calculated by thread_1, the value of C12 needs to be calculated by
thread_2 and so on. You must use M×P threads to complete this multiplication.
4. The input matrices A and B will be described in two input files. Your program must accept the two input
files and the output file as command-line arguments in this format:
./matrix-multiply input-file1 input-file2 outfile
5. Each line of the input file will describe each row of a matrix. Each element on a line is separated by 1 or
more whitespace characters. A whitespace character is a space or tab for this application. Extra whitespace
characters may be present. For example, to specify the matrices A and B:
3
ECE-3574: Applied Software Engineering, Fall 2014
Homework 5
the 2 input files may have the format:
Input-file1 Input-file2
1 4
2 5
3 6
8 7 6
5 4 3
6. The input files will contain the matrices A and B, respectively, for any values of M, N and P. M, N and P
are not given explicitly. They should be inferred from the input files.
7. The outer dimensions of the matrices are not necessarily the same. The output matrix must be sized
according to these dimensions.
8. You should also check for the correctness of the input files. The input files may contain either integer
values or decimal values (but not both). The file specifying matrix A may not mix integer and decimal values
(nor may the file specifying B). The file for matrix A and the file for matrix B must have the same value type.
9. An integer value is an optional minus sign followed by 1 or more digits. A decimal value is an optional
minus sign followed by 1 or more digits followed by a decimal point followed by exactly 4 digits.
10. Reading the two input files must be done in parallel, using two threads spawned by the main thread.
11. The output file will contain the resultant matrix C (computed by your program) in the same format as the
input files. It will contain the same kind of values (integer or decimal) as the input files. Once the
multiplication is done, the parent thread (e.g., main thread) may write the resultant C matrix in the output file.
12. You are NOT allowed to use QThreads for this homework. You need to use the POSIX “pthread” APIs.
You would have to #include
to the pthread libraries. For example, if you write a multi-threaded application using pthreads in a file
named main.cpp, the compilation step may be the following command:
g++ -pthread main.cpp -o matrix-multiply
13. You should use qmake for building this project and you are free to reuse classes from previous
homeworks and the book’s library (e.g., ArgumentList).
14. Make sure to properly implement error handling in your program. An error message must be printed for
the following errors:
I. Incorrectly formatted command line arguments
II. Unopenable, unreadable or unwritable files where doing so is necessary
III. Multiple-length rows for a single matrix
IV. Data format disagreement within and between matrices
V. Matrix inner dimension mismatch
15. Your program will not be expected to handle the case in which a matrix would have a 0 sized dimension.
16. Make sure you implement appropriate synchronization mechanisms (mutexes, semaphores, etc) if/where
needed. Your main cpp file should have a comment at the top of the file, where you explain where you used
such mechanisms and why, or why you didn’t have to use any. This should be around 50-200 words.
Submission
1. Please ensure that you submit before the deadline.
2. Include the “.pro” files for your projects.
