C言語と並列処理 – 初心者でも理解できる10ステップ

#include <stdio.h>
#include <pthread.h>

void *thread_function(void *arg) {
    printf("Hello, Thread!\n");
    return NULL;
}

int main() {
    pthread_t thread_id;

    if(pthread_create(&thread_id, NULL, thread_function, NULL) != 0) {
        printf("Failed to create thread.\n");
        return 1;
    }

    pthread_join(thread_id, NULL);

    return 0;
}

#include <stdio.h>
#include <pthread.h>

void *thread_function1(void *arg) {
    printf("Hello, I am Thread 1.\n");
    return NULL;
}

void *thread_function2(void *arg) {
    printf("Hello, I am Thread 2.\n");
    return NULL;
}

int main() {
    pthread_t thread_id1, thread_id2;

    if(pthread_create(&thread_id1, NULL, thread_function1, NULL) != 0) {
        printf("Failed to create thread 1.\n");
        return 1;
    }

    if(pthread_create(&thread_id2, NULL, thread_function2, NULL) != 0) {
        printf("Failed to create thread 2.\n");
        return 1;
    }

    pthread_join(thread_id1, NULL);
    pthread_join(thread_id2, NULL);

    return 0;
}

Hello, I am Thread 1.
Hello, I am Thread 2.

#include <pthread.h>
#include <stdio.h>
#define N 1000000
#define NUM_THREADS 10

int array[N];
int sum[NUM_THREADS] = {0};

void* SumArray(void* arg) {
  int id = (int)arg;
  int start = id * (N/NUM_THREADS);
  int end = start + (N/NUM_THREADS);

  for (int i = start; i < end; i++) {
    sum[id] += array[i];
  }

  return NULL;
}

int main() {
  pthread_t threads[NUM_THREADS];

  for (int i = 0; i < N; i++) {
    array[i] = i;
  }

  for (int i = 0; i < NUM_THREADS; i++) {
    pthread_create(&threads[i], NULL, SumArray, (void*)i);
  }

  for (int i = 0; i < NUM_THREADS; i++) {
    pthread_join(threads[i], NULL);
  }

  int total_sum = 0;
  for (int i = 0; i < NUM_THREADS; i++) {
    total_sum += sum[i];
  }

  printf("Total: %d\n", total_sum);

  return 0;
}

#include <pthread.h>
#include <stdio.h>

int shared_data = 0;

void* UpdateData(void* arg) {
  for (int i = 0; i < 10000; i++) {
    shared_data++;
  }
  return NULL;
}

int main() {
  pthread_t thread1, thread2;

  pthread_create(&thread1, NULL, UpdateData, NULL);
  pthread_create(&thread2, NULL, UpdateData, NULL);

  pthread_join(thread1, NULL);
  pthread_join(thread2, NULL);

  printf("Updated shared data: %d\n", shared_data);

  return 0;
}

#include <pthread.h>
#include <stdio.h>

// データ競合を起こす可能性のある変数
int count = 0;

// スレッドが実行する関数
void* increment(void* arg) {
    for (int i = 0; i < 1000000; i++) {
        count++;
    }
    return NULL;
}

int main() {
    pthread_t thread1, thread2;

    // ２つのスレッドを作成して関数を実行
    pthread_create(&thread1, NULL, increment, NULL);
    pthread_create(&thread2, NULL, increment, NULL);

    // ２つのスレッドが終了するのを待つ
    pthread_join(thread1, NULL);
    pthread_join(thread2, NULL);

    printf("Count: %d\n", count);
    return 0;
}

#include <pthread.h>
#include <stdio.h>

int count = 0;
pthread_mutex_t mutex;

void* increment(void* arg) {
    for (int i = 0; i < 1000000; i++) {
        pthread_mutex_lock(&mutex);
        count++;
        pthread_mutex_unlock(&mutex);
    }
    return NULL;
}

int main() {
    pthread_t thread1, thread2;

    pthread_mutex_init(&mutex, NULL);

    pthread_create(&thread1, NULL, increment, NULL);
    pthread_create(&thread2, NULL, increment, NULL);

    pthread_join(thread1, NULL);
    pthread_join(thread2, NULL);

    pthread_mutex_destroy(&mutex);

    printf("Count: %d\n", count);
    return 0;
}

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

void main() {
    pid_t pid = fork();

    if (pid == 0) {
        printf("これは子プロセスです\n");
    } else if (pid > 0) {
        printf("これは親プロセスです\n");
    } else {
        printf("プロセスの生成に失敗しました\n");
    }
}

#include <stdio.h>
#include <pthread.h>

void* task(void* arg) {
    int i;
    for (i = 0; i < 5; i++) {
        printf("スレッドID：%lu, 優先度：%d\n", pthread_self(), *((int*)arg));
    }
    return NULL;
}

void main() {
    pthread_t thread1, thread2;
    int priority1 = 1, priority2 = 2;

    pthread_create(&thread1, NULL, task, &priority1);
    pthread_create(&thread2, NULL, task, &priority2);

    pthread_join(thread1, NULL);
    pthread_join(thread2, NULL);
}

#include <pthread.h>
#include <stdio.h>

#define NUM_THREADS 4
#define TASK_SIZE 25000

void *perform_work(void *argument)
{
  int passed_in_value;

  passed_in_value = *((int *)argument);
  printf("Hello World! It's me, thread with argument %d!\n", passed_in_value);

  int i, sum = 0;
  for(i = 0; i <= TASK_SIZE; i++) {
    sum += i;
  }
  printf("Sum for thread %d is %d\n", passed_in_value, sum);

  pthread_exit(0);
}

int main(int argc, char **argv)
{
  pthread_t threads[NUM_THREADS];
  int thread_args[NUM_THREADS];
  int result_code, index;

  for (index = 0; index < NUM_THREADS; ++index) {
    thread_args[index] = index;
    printf("In main: creating thread %d\n", index);
    result_code = pthread_create(&threads[index], NULL, perform_work, (void *)&thread_args[index]);
  }

  for (index = 0; index < NUM_THREADS; ++index) {
    result_code = pthread_join(threads[index], NULL);
  }

  return 0;
}