[Spice-devel] [PATCH spice] reds: increase listening socket backlog

[Christophe Fergeau]

Hey,

On Wed, Jan 21, 2015 at 04:46:07PM +0100, Marc-André Lureau wrote:
> With TCP socket, the backlog doesn't seem to be such an important value,
> perhaps because of latency or underlying protocol behaviour. However,
> on UNIX socket, it is fairly easy to reach the backlog limit and the
> client will get an EAGAIN error (not ECONNREFUSED as stated in
> listen(7)) that is not easy to deal with: attempting to reconnect in a
> loop might busy-loop forever as there are no guarantee the server will
> accept new connections, so it will be inherently racy.
> 
> Typically, Spice server can easily have up to 15 concurrent incoming
> connections that are established during initialization of the session,
> so let's raise the backlog limit to the default system value, which is
> 128 on Linux to avoid any guesses.

128 is the default _maximum_ system value, ACK with that fixed.

Christophe

> ---
>  server/reds.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/server/reds.c b/server/reds.c
> index b9030c0..b4053f5 100644
> --- a/server/reds.c
> +++ b/server/reds.c
> @@ -2424,7 +2424,7 @@ static int reds_init_socket(const char *addr, int portnr, int family)
>      return -1;
>  
>  listen:
> -    if (listen(slisten,1) != 0) {
> +    if (listen(slisten, SOMAXCONN) != 0) {
>          spice_warning("listen: %s", strerror(errno));
>          close(slisten);
>          return -1;
> -- 
> 2.1.0
> 
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