Manlio,

Yes, I see what you're saying. It is always going to be a problem if the listener cannot consume the data fast
enough. In any case, if you really dig deep, you can see that NGINX is asynch in that it
always reads from a socket only when it is ready to be read
(select/poll/epoll/kevent etc fires). But, as you know, NGINX uses non-blocking sockets. So when it wants to write to a socket (as far as my limited understanding goes),
it doesn't wait for it to be ready-to-write. It just goes and does a write to
the socket. If the kernel deems that the write would have blocked, it will
return EAGAIN (see send(2)) , rather than block the caller, if that's what
you're worried about.

----- Original Message ----- From: "Manlio Perillo" <manlio_perillo-VGgt2q2+T+FeoW...@public.gmane.org>

This is not as easy as it seems. First of all with the current architecture of Nginx, writing to the error log is assumed to be synchronous.

This means that if you want to send log messages to a TCP server the performance will be bad.

You can use an UDP connection, but what happens if Nginx sends data more quickly then the server is able to read? UDP has no flow control.