upgraded the nginx core to 1.19.9. (#717)

patches/nginx-1.19.9-reuseport_close_unused_fds.patch

@@ -0,0 +1,38 @@
+diff --git a/src/core/ngx_connection.c b/src/core/ngx_connection.c
+--- a/src/core/ngx_connection.c
++++ b/src/core/ngx_connection.c
+@@ -1118,6 +1118,12 @@ ngx_close_listening_sockets(ngx_cycle_t *cycle)
+     ls = cycle->listening.elts;
+     for (i = 0; i < cycle->listening.nelts; i++) {
+ 
++#if (NGX_HAVE_REUSEPORT)
++        if (ls[i].fd == (ngx_socket_t) -1) {
++            continue;
++        }
++#endif
++
+         c = ls[i].connection;
+ 
+         if (c) {
+diff --git a/src/event/ngx_event.c b/src/event/ngx_event.c
+--- a/src/event/ngx_event.c
++++ b/src/event/ngx_event.c
+@@ -775,6 +775,18 @@ ngx_event_process_init(ngx_cycle_t *cycle)
+ 
+ #if (NGX_HAVE_REUSEPORT)
+         if (ls[i].reuseport && ls[i].worker != ngx_worker) {
++            ngx_log_debug2(NGX_LOG_DEBUG_CORE, cycle->log, 0,
++                           "closing unused fd:%d listening on %V",
++                           ls[i].fd, &ls[i].addr_text);
++
++            if (ngx_close_socket(ls[i].fd) == -1) {
++                ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_socket_errno,
++                              ngx_close_socket_n " %V failed",
++                              &ls[i].addr_text);
++            }
++
++            ls[i].fd = (ngx_socket_t) -1;
++
+             continue;
+         }
+ #endif