Lab Assignment--Threads and Mutexes

Lab Code

To get the sample and exercise code, please use the following commands in your cs330 directory:

  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 modify a "findMin" function written in C to a thread 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 findMin function
modify the variable that is printed to display the global minimum

Change findMin

turn findMin into a thread function (hint: two void *)
create a pointer to a struct ArrayPackage
you might want to store the pieces of 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 minimum of the array
note: anytime you print or anytime you work with the global MIN, 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.
Please ensure that you are cleaning up memory for the arguments allocated in main

Sample runs:

~/Lab6b$ ./demo
How many threads? 10
How big is the array (100 elements or more)?135
475 459 103 45 98 184 28 175 82 356 282 376 430 357 208 
387 37 49 99 361 61 40 105 21 233 121 5 328 270 389 
369 96 347 323 492 296 7 372 323 88 227 104 463 8 312 
22 394 201 70 492 61 482 384 166 354 116 286 359 443 407 
247 164 3 445 486 494 92 344 365 414 284 443 17 98 450 
181 120 343 381 41 187 441 23 70 458 376 37 244 86 332 
2 332 347 4 128 184 350 220 28 66 485 311 9 2 260 
458 34 379 153 414 272 339 206 294 260 164 21 148 259 107 
331 260 290 177 116 418 361 317 489 240 382 473 402 390 326 

Start:0, End:13
Start:13, End:26
Start:26, End:39
Start:39, End:52
Start:65, End:78
Start:78, End:91
Start:52, End:65
Start:104, End:117
Start:91, End:104
Start:117, End:135
min value in array is: 2
~/Lab6b$ ./demo
How many threads? 5
How big is the array (100 elements or more)?100
373 97 392 20 227 216 94 235 375 375 310 407 169 441 366 
221 317 319 62 491 120 444 411 406 257 227 50 167 354 232 
176 226 328 67 97 54 282 191 141 8 417 450 266 86 391 
132 158 59 302 219 401 422 14 311 179 122 37 228 288 243 
311 463 468 138 381 65 44 14 255 184 373 23 133 139 108 
375 270 117 285 71 187 185 344 200 348 374 321 236 453 460 
478 263 422 298 253 154 362 296 167 468 
Start:0, End:20
Start:60, End:80
Start:20, End:40
Start:40, End:60
Start:80, End:100
min value in array is: 8

Deliverables:

Submit 3 files to URCourses:

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