{"id":3187,"date":"2023-02-20T04:54:31","date_gmt":"2023-02-20T04:54:31","guid":{"rendered":"https:\/\/www.goodacademic.com\/blog\/questions\/mplement-a-solution-to-the-critical-section-problem-for-2-threads-using-mutex-locks\/"},"modified":"2023-02-20T04:54:31","modified_gmt":"2023-02-20T04:54:31","slug":"mplement-a-solution-to-the-critical-section-problem-for-2-threads-using-mutex-locks","status":"publish","type":"questions","link":"https:\/\/www.goodacademic.com\/blog\/questions\/mplement-a-solution-to-the-critical-section-problem-for-2-threads-using-mutex-locks\/","title":{"rendered":"mplement a solution to the critical section problem for 2 threads using mutex locks"},"content":{"rendered":"
\n

in C programming<\/p>\n

Implement a solution to the critical section problem for 2 threads using mutex locks. Specifically, in pthreads<\/strong> using pthread_<\/strong>mutex_<\/strong>trylock <\/strong>and pthread_mutex_unlock<\/strong>.<\/p>\n

both two threads need to concurrently<\/strong> increment a shared variable<\/strong> called counter<\/strong> <\/em>by one 2,000,000<\/strong> times starting from zero<\/strong>. all global memory is shared among threads of a process. Both threads need to count to 2,000,000 which means the only<\/strong> correct<\/strong> overall count is 4,000,000<\/strong>.<\/p>\n

the shared variable count should be defined as follows:<\/p>\n

struct shared_data<\/strong><\/em>
{<\/strong><\/em>
int value; \/* shared variable to store result*\/<\/strong><\/em>
};<\/strong><\/em><\/p>\n

struct shared_data *counter;<\/strong><\/em><\/p>\n

remember to allocate memory to your shared data as follows:<\/p>\n

counter = (struct shared_data *) malloc(sizeof(struct shared_data));<\/strong><\/em><\/p>\n

Thread1<\/strong> needs to be designed in a way that every time it sees (counter\u00e2\u02c6\u2019> value<\/strong>%100) == 0<\/strong> it increments counter\u00e2\u02c6\u2019> value by 100<\/strong> (bonus<\/strong>). That counts for 100 individual updates<\/strong>. You also need to keep track of how many times the thread got the bonus and report<\/strong> it in its remainder<\/strong> section.<\/p>\n

Thread2<\/strong> does not get any bonus, it only increments counter->value<\/em> by 1<\/strong>.<\/p>\n

you should prevent<\/strong> each thread from counting to more than 2,000,000.<\/p>\n

remember the parent process needs to wait<\/strong> for its 2 threads to join.<\/strong><\/p>\n

in the main body of your code add the following lines :<\/p>\n

\/* Required to schedule thread independently. Otherwise, use NULL in place of attr. *\/
pthread_attr_init(&attr[0]);<\/strong>
pthread_attr_setscope(&attr[0], PTHREAD_SCOPE_SYSTEM); <\/strong>\/* system-wide contention *\/
\/* end to schedule thread independently *\/<\/p>\n

remember to initialize the mutex using pthread_mutex_init .<\/strong><\/p>\n

Make comments indicating the following sections in your code:<\/p>\n