do not schedule a new DNS check if the worker is exiting which resolves #1

Author: wandenberg

ngx_http_upstream_dynamic_servers.c

@@ -543,6 +543,11 @@ static void ngx_http_upstream_dynamic_server_resolve_handler(ngx_resolver_ctx_t
   ngx_log_debug(NGX_LOG_DEBUG_CORE, ctx->resolver->log, 0, "upstream-dynamic-servers: Refreshing DNS of '%V' in %ims", &ctx->name, refresh_in);
   ngx_resolve_name_done(ctx);
 
+  if (ngx_exiting) {
+    ngx_log_debug(NGX_LOG_DEBUG_CORE, ctx->resolver->log, 0, "upstream-dynamic-servers: worker is about to exit, do not set the timer again");
+    return;
+  }
+
   ngx_event_t *timer;
   timer = ngx_pcalloc(ngx_cycle->pool, sizeof(ngx_event_t));