I found that :
[code]
#define NGX_LISTEN_BACKLOG 511
[/code]
and use it as the backlog of listen()
[code]
ls[i].backlog = NGX_LISTEN_BACKLOG;
if (listen(s, ls[i].backlog) == -1) {
[/code]
Does it mean that only 511 connection could be accept at the same time ?
May I modify it to 1024 or higher( I am sure use it less than SOMAXCONN )