`pthread_create`的`pthread_t *`参数需要多长时间才能存活？(How long does the `pthread_t*` argument to `pthread_create` need to survive?)

 pthread_create(3)的签名是： 
 
   int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
                      void *(*start_routine) (void *), void *arg);
 
 pthread_t *thread参数的存储持续时间有哪些要求？ pthread_create的手册页说： 
 
 
 
 在返回之前，成功调用pthread_create()会将新线程的ID存储在线程指向的缓冲区中; 
 
 
 但是不清楚它是否意味着它将值存储在那里以便调用者可以检查它，或者它是否使用该缓冲区来存储值（暗示缓冲区需要在子线程的整个生命周期内保持可用）。 
 
 同样， pthread_self说它返回 
 
 
 
 创建此线程的pthread_create(3)调用中*thread中返回的相同值。 
 
 
 但是不清楚它是否意味着它返回存储在*thread 的值或者等于 *thread返回的值 。 
 
 具体来说，我想知道这样的事情是否合法： 
 
void make_thread(void) {
  pthread_t tid;
  return pthread_create(&tid, NULL, some_fn, NULL);
}
 
 或者如果tid需要是malloc 。 当我把tid放在堆栈上时，我在与_Unwind_ForcedUnwind相关的valgrind中得到了一堆错误，这让我怀疑*thread需要在子线程的生命周期内保持有效。 

The signature of pthread_create(3) is:
 
   int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
                      void *(*start_routine) (void *), void *arg);
 
What are the requirements on the storage duration of the pthread_t *thread argument? The man page for pthread_create says:
 
 
 
Before returning, a successful call to pthread_create() stores the ID of the new thread in the buffer pointed to by thread;
 
 
But it's not clear if it means that it stores the value there so that the caller can examine it, or if it uses that buffer to store the value (implying that the buffer needs to stay usable for the whole lifetime of the child thread). 
 
Similarly, pthread_self says it returns
 
 
 
the same value that is returned in *thread in the pthread_create(3) call that created this thread.
 
 
but it's not clear if it means that it returns the value stored in *thread or a value equal to what was returned in *thread.
 
Concretely, I'm wondering if it's legal to have something like:
 
void make_thread(void) {
  pthread_t tid;
  return pthread_create(&tid, NULL, some_fn, NULL);
}
 
or if tid needs to be malloc'd. When I put tid on the stack, I get a bunch of errors in valgrind related to _Unwind_ForcedUnwind, which makes me suspect that *thread needs to remain valid for the lifetime of the child thread.

原文：https://stackoverflow.com/questions/35928654