* pre_select hooks which may set the timeout and add any file descriptors to
* the fd sets of \a s. Next, it calls para_select() and makes the result available
* to the registered tasks by calling their post_select hook.
* pre_select hooks which may set the timeout and add any file descriptors to
* the fd sets of \a s. Next, it calls para_select() and makes the result available
* to the registered tasks by calling their post_select hook.