假设 F2（）使用在同一个互斥体的共享结构来读取线程个使用修改数据的数据前锁定，我看不出有什么问题。

Assuming that f2() uses the same mutex in the shared structure to lock before reading the data that the thread th uses to modify the data, I don't see any issues.

如果你有多个线程调用 F2（），您可能需要使用读写锁的线程状态读取和写入个。互斥仍然可以用于序列化线程创建检查。你也可以使用 pthread_rwlock_wrlock（）连载个创作，但code可以说是不太清楚。

If you have more than one thread calling f2(), you may want to use a read-write lock for reading and writing of the thread status of th. The mutex could still be used to serialize the thread creation check. You could also use a pthread_rwlock_wrlock() to serialize th creation, but the code is arguably less clear.

使用互斥锁序列化）个创建F2（：

Using a mutex to serialize th creation in f2():

pthread_rwlock_rdlock(&shared.rwlock);
result = shared.th_status;
if (! shared.th_created) {
    pthread_mutex_lock(&shared.mutex);
    if (! shared.th_created) {
        pthread_create(...);
        shrared.th_created = 1;
    }
    pthread_mutex_unlock(&shared_mutex);
}
pthread_rwlock_unlock(&shared.rwlock);
return result;

使用读写锁将序列号）个创建F2（：

Using the read-write lock to serialize th creation in f2():

pthread_rwlock_rdlock(&shared.rwlock);
result = shared.th_status;
if (! shared.th_created) {
    pthread_rwlock_unlock(&shared.rwlock);
    pthread_rwlock_wrlock(&shared.rwlock);
    if (! shared.th_created) {
        pthread_create(...);
        shrared.th_created = 1;
    }
}
pthread_rwlock_unlock(&shared.rwlock);
return result;