Linux C 多线程互斥锁及线程同步问题 （二）

需求：主线程创建子线程后等待子线程真正运行。然后主线程向子线程发送同步请求，保证主线程的同步请求信号不丢失。
测试代码:(来自百度，修改。。。)

#include <sys/time.h>#include <pthread.h>#include <unistd.h>#include <stdio.h>#include <string.h>#include <stdlib.h>static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;static int count = 0;struct timeval tv1,tv2,tv3;int timestamp1,timestamp2,timestamp3;/*释放节点内存 */static void cleanup_handler(void *arg){    printf("Cleanup handler of second thread.\n");    free(arg);    (void)pthread_mutex_unlock(&mtx);}static void *thread_func(void *arg){int time_fun=0;printf("try lock10........\n");pthread_mutex_lock(&mtx);printf("locked10........\n");pthread_cond_signal(&cond);printf("sended msg to main........\n");pthread_mutex_unlock(&mtx); //解锁    while (1)    {        printf("wait msg from mian................\n");pthread_cond_wait(&cond, &mtx);printf("get msg from mian.....count：%d.....\n",count);    }    return 0;}int main(void){int time_create=0;    pthread_t tid;    int i;    pthread_mutexattr_t mutex_attr;pthread_condattr_t cond_attr;pthread_mutexattr_init(&mutex_attr);pthread_condattr_init(&cond_attr);pthread_mutex_init(&mtx, &mutex_attr);pthread_cond_init(&cond, &cond_attr);pthread_condattr_destroy(&cond_attr);pthread_mutexattr_destroy(&mutex_attr);    gettimeofday(&tv1, NULL);    timestamp1 = tv1.tv_sec * 1000 * 1000 + tv1.tv_usec;    pthread_create(&tid, NULL, thread_func, NULL);    printf("try lock00...........\n");    pthread_mutex_lock(&mtx);    printf("locked00...waiting msg from son.......\n");    pthread_cond_wait(&cond, &mtx);    printf("recved msg from son.......\n");    pthread_mutex_unlock(&mtx); //解锁    //usleep(1000);    for (i = 0; i < 10; i++)    {    printf("try lock 02.........\n");        pthread_mutex_lock(&mtx); //需要操作head这个临界资源，先加锁，        printf("locked 02.........\n");        count = i;        pthread_cond_signal(&cond);        printf("try unlock 02.........\n");        pthread_mutex_unlock(&mtx); //解锁        printf("unlocked 02.........\n");        sleep(1);    }    printf("thread 1 wanna end the cancel thread 2.\n");    pthread_cancel(tid);    pthread_join(tid, NULL);    printf("All done -- exiting\n");    return 0;}

猜想，主线程创建子线后阻塞等待子线程同步请求，应该可以达到我的需求，事实是第一个主线程的同步请求仍然丢失（偶尔不会丢失）。

暂时就只有休眠等待了修时间增加到1ms才稳定下来。（蓝色）

猜想，提高子线程的优先级可能会解决。等待下次实验吧。