"It is heavyweight. It requires constantly registering and unregistering processes from the file descriptors, potentially thousands of descriptors, thousands times per second."
Can someone clarify what this tries to say. Thanks.
Imagine a kernel has a data structure for each socket. When a process blocks on that socket, a kernel must "register" it on it.
So that - when an event on a socket happens, the kernel instantly knows which processes to wake up. A reverse lookup: given socket, return list of blocking processes.
I'm arguing that maintaining this reverse lookup is a hard work, especially when you need to set it up it and tear it down on every call to select().
Can someone clarify what this tries to say. Thanks.