Linux多線程編程簡例6個

//建立多線程#include <stdio.h>#include <string.h>#include <stdlib.h>#include <pthread.h>#include <unistd.h>pthread_t ntid;void printids(const char *s){pid_tpid;pthread_ttid;pid = getpid();tid = pthread_self();printf("%s pid %u tid %u (0x%x)\n", s, (unsigned int)pid, (unsigned int)tid, (unsigned int)tid);}void *thr_fn(void *arg){printids(arg);return NULL;}int main(void){int err;err = pthread_create(&ntid, NULL, thr_fn, "new thread:");if(err != 0){fprintf(stderr, "can't create thread: %s\n", strerror(err));;}printids("main thread:");sleep(1);return 0;}

//pthread_join#include <stdio.h>#include <stdlib.h>#include <pthread.h>#include <unistd.h>void *thr_fn1(void *arg){printf("thread 1 returning\n");return (void*)1;}void *thr_fn2(void *arg){printf("thread 2 exiting\n");pthread_exit((void*)2);}void *thr_fn3(void *arg){while(1){printf("thread 3 writing\n");sleep(1);}}int main(void){pthread_t  tid;void *tret;pthread_create(&tid, NULL, thr_fn1, NULL);pthread_join(tid, &tret);printf("thread 1 exit code %d\n", (int)tret);pthread_create(&tid, NULL, thr_fn2, NULL);pthread_join(tid, &tret);printf("thread 2 exit code %d\n", (int)tret);pthread_create(&tid, NULL, thr_fn3, NULL);sleep(3);pthread_cancel(tid);pthread_join(tid, &tret);printf("thread 3 exit code %d\n", (int)tret);return 0;}

//示範兩個線程操作全域變數時相互幹擾#include <stdio.h>#include <stdlib.h>#include <pthread.h>#define NLOOP 5000int counter;void *doit(void *);int main(void){pthread_t tidA, tidB;pthread_create(&tidA, NULL, &doit, NULL);pthread_create(&tidB, NULL, &doit, NULL);pthread_join(tidA, NULL);pthread_join(tidB, NULL);return 0;}void *doit(void *vptr){int i, val;for(i=0; i<NLOOP; i++){val = counter;printf("%x: %d\n", (unsigned int)pthread_self(), val+1);counter = val + 1;}return NULL;}

//示範兩個線程操作全域變數時相互幹擾， 試用mutex解決#include <stdio.h>#include <stdlib.h>#include <pthread.h>#define NLOOP 5000intcounter;pthread_mutex_tcounter_mutex = PTHREAD_MUTEX_INITIALIZER;//互斥鎖初始化void *doit(void *);int main(void){pthread_t tidA, tidB;pthread_create(&tidA, NULL, &doit, NULL);pthread_create(&tidB, NULL, &doit, NULL);pthread_join(tidA, NULL);pthread_join(tidB, NULL);return 0;}void *doit(void *vptr){int i, val;for(i=0; i<NLOOP; i++){pthread_mutex_lock(&counter_mutex);//獲得鎖val = counter;printf("%x: %d\n", (unsigned int)pthread_self(), val+1);counter = val + 1;pthread_mutex_unlock(&counter_mutex);//解鎖}return NULL;}

// pthread_cond,生產者、消費者模型#include <stdlib.h>#include <pthread.h>#include <stdio.h>struct msg{struct msg *next;int num;};struct msg *head;pthread_cond_t has_product = PTHREAD_COND_INITIALIZER;pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;void *consumer(void *p){struct msg *mp;for(;;){pthread_mutex_lock(&lock);while(head == NULL){pthread_cond_wait(&has_product, &lock);// 線程調用pthread_cond_wait在一個Condition Variable上// 阻塞等待，這個函數做以下三步操作：// 1. 釋放Mutex// 2. 阻塞等待// 3. 當被喚醒時，重新獲得Mutex並返回 }mp = head;head = mp->next;pthread_mutex_unlock(&lock);printf("Consume -%d\n", mp->num);free(mp);sleep(rand() % 5);}return NULL;}void *producer(void *p){struct msg *mp;for(;;){mp = malloc(sizeof(struct msg));mp->num = rand() % 1000 + 1;printf("Produce +%d\n", mp->num);pthread_mutex_lock(&lock);mp->next = head;head = mp;pthread_mutex_unlock(&lock);pthread_cond_signal(&has_product);// 線程可以調用pthread_cond_signal喚醒在// 某個Condition Variable上等待的另一個線程sleep(rand() % 5);}}int main(){pthread_t pid, cid;pthread_create(&pid, NULL, producer, NULL);pthread_create(&cid, NULL, consumer, NULL);pthread_join(pid, NULL);pthread_join(cid, NULL);return 0;}

//sem, 生產者、消費者模型#include <stdlib.h>#include <pthread.h>#include <stdio.h>#include <semaphore.h>#defineNUM5sem_t blank_number, product_number;int queue[NUM];pthread_cond_t has_product = PTHREAD_COND_INITIALIZER;pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;void *consumer(void *p){int n = 0;for(;;){sem_wait(&product_number);printf("Consume -%d\n", queue[n]);queue[n] = 0;sem_post(&blank_number);n = (n + 1) % NUM;sleep(rand() % 5);}return NULL;}void *producer(void *arg){int n = 0;for(;;){sem_wait(&blank_number);queue[n] = rand() % 1000 + 1;printf("Produce +%d\n", queue[n]);sem_post(&product_number);n = (n + 1) % NUM;sleep(rand() % 5);}}int main(){pthread_t pid, cid;sem_init(&blank_number, 0, NUM);sem_init(&product_number, 0, 0);pthread_create(&pid, NULL, producer, NULL);pthread_create(&cid, NULL, consumer, NULL);pthread_join(pid, NULL);pthread_join(cid, NULL);sem_destroy(&blank_number);sem_destroy(&product_number);return 0;}

參考資料：http://www.eefocus.com/html/09-11/26160910394Yba.shtml