diff src/core/ngx_connection.c @ 7697:b9071b875194

Core: added a warning about reusing connections. Previously, reusing connections happened silently and was only visible in monitoring systems. This was shown to be not very user-friendly, and administrators often didn't realize there were too few connections available to withstand the load, and configured timeouts (keepalive_timeout and http2_idle_timeout) were effectively reduced to keep things running. To provide at least some information about this, a warning is now logged (at most once per second, to avoid flooding the logs).
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 10 Aug 2020 18:52:59 +0300
parents 9c038f5e0464
children 5440ff4ac6fc
line wrap: on
line diff
--- a/src/core/ngx_connection.c
+++ b/src/core/ngx_connection.c
@@ -1298,6 +1298,19 @@ ngx_drain_connections(ngx_cycle_t *cycle
     ngx_queue_t       *q;
     ngx_connection_t  *c;
 
+    if (cycle->reusable_connections_n == 0) {
+        return;
+    }
+
+    if (cycle->connections_reuse_time != ngx_time()) {
+        cycle->connections_reuse_time = ngx_time();
+
+        ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
+                      "%ui worker_connections are not enough, "
+                      "reusing connections",
+                      cycle->connection_n);
+    }
+
     n = ngx_max(ngx_min(32, cycle->reusable_connections_n / 8), 1);
 
     for (i = 0; i < n; i++) {