Lab Assignment--Threads and Mutexes

Lab Code

  curl https://www.labs.cs.uregina.ca/330/Threads/Lab5.zip -O -s
  unzip Lab5.zip

(Please do this lab on os1 or os2)

This week, we will be working with a countHeads function, which counts the number of 1's (representing heads) in an array of 1's and zeros. Your job is to convert the function from a regular function, written in C, to a threaded function. As a thread function, you will give it a portion of the array to work with, depending on the size of the array and the number of threads. Some of the code is provided for you already in main.c. You will notice that certain things are missing.

Change main

• load the onePack instance with the array, the start and end of indices that you want to work within the array
• for the last thread, the end index will be the size of the array
• add the call to the pthread_create
• add the call to the pthread_join
• remove the original call to the countHeads function
• modify the variable that is printed to display the global NUM_HEADS

Change countHeads

• turn countHeads into a thread function (hint: two void *)
• create a pointer to a struct ArrayPackage
• you might want to store the pieces of the ArrayPackage into variables
• print the start and the end that is sent to the thread function using the ArrayPackage
• loop from start to end to find the number of heads in that portion of the array
• note: anytime you print or anytime you work with the global NUM_HEADS, you will want to have a mutex_lock and mutex_unlock around that code
• Although there are different approaches, the approach we are expecting is that this function returns NULL.
  • Possible check question: be prepared to return and print the integer specified by your lab instructor
• Please ensure that you are cleaning up memory for the arguments allocated in main

Sample runs:

os1:~/cs330/Lab5$ ./demo
How many threads? 10
How big is the array (100 elements or more)?135
0 0 1 1 0 0 1 1 0 0 0 1 0 0 1 
1 0 0 1 1 0 1 1 0 0 0 0 1 1 1 
0 1 1 1 1 0 0 0 1 0 0 1 0 0 1 
1 1 0 1 0 1 1 1 1 1 1 1 1 0 1 
1 1 0 0 0 1 0 0 1 0 1 1 1 1 1 
1 0 0 1 1 0 0 0 1 1 1 0 1 0 1 
0 1 0 0 0 0 0 0 1 1 0 0 1 0 1 
0 1 1 1 0 0 1 0 0 1 0 1 1 1 1 
0 1 1 0 1 1 1 1 1 0 1 0 0 0 0 

Checking result: 72
Start:0 End:13
Start:13 End:26
Start:26 End:39
Start:39 End:52
Start:52 End:65
Start:65 End:78
Start:78 End:91
Start:91 End:104
Start:104 End:117
Start:117 End:135
The number of heads coin tosses is: 72

os1:~/cs330/Lab5$ ./demo
How many threads? 5
How big is the array (100 elements or more)?100
0 0 1 0 0 0 1 1 1 1 0 1 0 0 0 
1 1 0 0 1 1 0 1 0 1 0 1 0 0 1 
0 0 1 1 1 0 1 0 1 0 1 1 0 1 1 
0 0 0 0 1 0 1 1 1 1 0 1 1 0 1 
0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 
0 1 1 1 1 0 1 1 1 0 0 1 0 1 1 
1 1 0 1 1 1 0 0 1 0

Checking result: 54
Start:0 End:20
Start:20 End:40
Start:40 End:60
Start:60 End:80
Start:80 End:100
The number of heads coin tosses is: 54

Deliverables:

Submit 3 files to URCourses:

1. The code (main.c and functions.c)
2. A few sample runs captured in a script file (saved as .txt)