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60 | // Copyright 2021 Jeisson Hidalgo-Cespedes <jeisson.hidalgo@ucr.ac.cr> CC-BY-4
// Creates an arbitrary amount of threads that greet in stdout
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int create_threads(size_t thread_count);
void* run(void* data);
int main(int argc, char* argv[]) {
size_t thread_count = sysconf(_SC_NPROCESSORS_ONLN);
if (argc == 2) {
if (sscanf(argv[1], "%zu", &thread_count) != 1 || errno) {
fprintf(stderr, "error: invalid thread count\n");
return EXIT_FAILURE;
}
}
int error = create_threads(thread_count);
return error;
}
int create_threads(size_t thread_count) {
int error = EXIT_SUCCESS;
pthread_t* threads = (pthread_t*) calloc(thread_count, sizeof(pthread_t));
if (threads) {
for (size_t index = 0; index < thread_count; ++index) {
if (pthread_create(&threads[index], /*attr*/ NULL, run, (void*)index)
== EXIT_SUCCESS) {
} else {
fprintf(stderr, "Could not create secondary thread %zu\n", index);
error = 21;
break;
}
}
printf("Hello from main thread\n");
for (size_t index = 0; index < thread_count; ++index) {
pthread_join(threads[index], /*value_ptr*/ NULL);
}
free(threads);
} else {
fprintf(stderr, "Could not allocate memory for %zu threads\n"
, thread_count);
error = 22;
}
return error;
}
void* run(void* data) {
const size_t thread_number = (size_t)data;
printf("Hello from secondary thread %zu\n", thread_number);
return NULL;
}
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