The "reuseport" option of the "listen" directive.

When configured, an individual listen socket on a given address is
created for each worker process.  This allows to reduce in-kernel lock
contention on configurations with high accept rates, resulting in better
performance.  As of now it works on Linux and DragonFly BSD.

Note that on Linux incoming connection requests are currently tied up
to a specific listen socket, and if some sockets are closed, connection
requests will be reset, see https://lwn.net/Articles/542629/.  With
nginx, this may happen if the number of worker processes is reduced.
There is no such problem on DragonFly BSD.

Based on previous work by Sepherosa Ziehau and Yingqi Lu.

3 files changed, 24 insertions, 0 deletions

diff --git a/src/http/ngx_http.c b/src/http/ngx_http.c
index adb4b6f36..4642559ea 100644
--- a/src/http/ngx_http.c
+++ b/src/http/ngx_http.c
@@ -1737,6 +1737,10 @@ ngx_http_init_listening(ngx_conf_t *cf, ngx_http_conf_port_t *port)
             break;
         }
 
+        if (ngx_clone_listening(cf, ls) != NGX_OK) {
+            return NGX_ERROR;
+        }
+
         addr++;
         last--;
     }
@@ -1815,6 +1819,10 @@ ngx_http_add_listening(ngx_conf_t *cf, ngx_http_conf_addr_t *addr)
     ls->fastopen = addr->opt.fastopen;
 #endif
 
+#if (NGX_HAVE_REUSEPORT)
+    ls->reuseport = addr->opt.reuseport;
+#endif
+
     return ls;
 }
 
diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index 1f034253d..f5255265e 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -4166,6 +4166,19 @@ ngx_http_core_listen(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 #endif
         }
 
+        if (ngx_strcmp(value[n].data, "reuseport") == 0) {
+#if (NGX_HAVE_REUSEPORT)
+            lsopt.reuseport = 1;
+            lsopt.set = 1;
+            lsopt.bind = 1;
+#else
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "reuseport is not supported "
+                               "on this platform, ignored");
+#endif
+            continue;
+        }
+
         if (ngx_strcmp(value[n].data, "ssl") == 0) {
 #if (NGX_HTTP_SSL)
             lsopt.ssl = 1;
diff --git a/src/http/ngx_http_core_module.h b/src/http/ngx_http_core_module.h
index e0ca2ce47..e6be5ac99 100644
--- a/src/http/ngx_http_core_module.h
+++ b/src/http/ngx_http_core_module.h
@@ -85,6 +85,9 @@ typedef struct {
 #if (NGX_HAVE_INET6 && defined IPV6_V6ONLY)
     unsigned                   ipv6only:1;
 #endif
+#if (NGX_HAVE_REUSEPORT)
+    unsigned                   reuseport:1;
+#endif
     unsigned                   so_keepalive:2;
     unsigned                   proxy_protocol:1;