Question

I have a question about pthread, when I create a variable inside a thread with malloc and then pass its pointer to a shared structure, i.e fifo, is the pointer passed by thread-1 will be accessed by thread2 ?

Please note that I have to code for the question above, I’m just trying to understand threading better, the below is just what I’m thinking about. The environment is pthread, c and linux

As far as I know threads are sharing the memory of their parent process, If that’s the case the below should be correct.

void *thread-1(void *pointer)
{
  int *intp = malloc(4);
  send_to_fifo(intp);
}


void *thread-2(void *pointer)
{
  int *iptr;
  iptr = read_from_fifo();
  do_something(iptr);
  free(iptr);
}

Answer 1

is the pointer passed by thread-1 will be accessed by thread2 ?

Yes: since all threads operate in a common memory space, this is allowed.

malloc, free, and other memory management functions are thread-safe by default, unless compiled with NO_THREADS.