Thread Pools in C (using the PTHREAD API)
main.c
#include <stdio.h>
#include <string.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#define THREAD_NUM 4
typedef struct Task {
int a, b;
} Task;
Task taskQueue[256];
int taskCount = 0;
pthread_mutex_t mutexQueue;
pthread_cond_t condQueue;
void executeTask(Task* task) {
usleep(50000);
int result = task->a + task->b;
printf("The sum of %d and %d is %d\n", task->a, task->b, result);
}
void submitTask(Task task) {
pthread_mutex_lock(&mutexQueue);
taskQueue[taskCount] = task;
taskCount++;
pthread_mutex_unlock(&mutexQueue);
pthread_cond_signal(&condQueue);
}
// 1 2 3 4 5
// 2 3 4 5
void* startThread(void* args) {
while (1) {
Task task;
pthread_mutex_lock(&mutexQueue);
while (taskCount == 0) {
pthread_cond_wait(&condQueue, &mutexQueue);
}
task = taskQueue[0];
int i;
for (i = 0; i < taskCount - 1; i++) {
taskQueue[i] = taskQueue[i + 1];
}
taskCount--;
pthread_mutex_unlock(&mutexQueue);
executeTask(&task);
}
}
int main(int argc, char* argv[]) {
pthread_t th[THREAD_NUM];
pthread_mutex_init(&mutexQueue, NULL);
pthread_cond_init(&condQueue, NULL);
int i;
for (i = 0; i < THREAD_NUM; i++) {
if (pthread_create(&th[i], NULL, &startThread, NULL) != 0) {
perror("Failed to create the thread");
}
}
srand(time(NULL));
for (i = 0; i < 100; i++) {
Task t = {
.a = rand() % 100,
.b = rand() % 100
};
submitTask(t);
}
for (i = 0; i < THREAD_NUM; i++) {
if (pthread_join(th[i], NULL) != 0) {
perror("Failed to join the thread");
}
}
pthread_mutex_destroy(&mutexQueue);
pthread_cond_destroy(&condQueue);
return 0;
}
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