How does facebook prevent exceeding max_execution_time in long polling empty responses?

Question

So, how does facebook return 200 status code when there are no new message/update?

I tried long polling and it works. the only problem I am facing right now is that I am encountering 500 Internal Server Error (exceeded max_execution_time) when the polling is not returning anything.

I do not want to alter the "max_execution_time" of the poll, but what I want is to return a 200 OK status code even when there are no new messages/updates.

Edit:
I've read from various sources including stackoverflow (sorry I've read too many and could not quote all of it here) where it says that I should return an empty response to get a 200 status code.

Now, the new problem is:

How can I return an empty body response while there is no new message/update (while "while" loop is running and about to reach max_execution_time) to prevent 500 Internal server error (exceeded max_execution_time).

In a more simple term:
how to return empty response before while loop reaches timeout

Answer 1

Okay I've found a workaround, or a neat or rather nasty solution haha!

A comment by a user named Adeel in this thread gave me the idea.

What I did was to set a time for the future 30 seconds from now:

$future = date("Y-m-d H:i:s", strtotime("+30 seconds"));

while ($last_number < $new_number){
    $now = date("Y-m-d H:i:s");
    if($now == $future){
        break 1;
    }

    //some codes for iteration and updating $last_number in this while loop
}

echo json_encode();

I do not know if this is the best way to achieve what I had in mind, but it is the only way that worked out so far.

If you guys have better solutions, I would be glad to know.

So in the end, I just had to break out of the loop haha how stupid cou