- Fix to log accept error ENFILE and EMFILE errno, but slowly, once

per 10 seconds. Also log accept failures when no slow down is used.

doc/Changelog

@@ -1,3 +1,7 @@
+12 August 2022: Wouter
+	- Fix to log accept error ENFILE and EMFILE errno, but slowly, once
+	  per 10 seconds. Also log accept failures when no slow down is used.
+
 5 August 2022: Wouter
 	- Fix #734 [FR] enable unbound-checkconf to detect more (basic)
 	  errors.

util/netevent.c

@@ -132,6 +132,8 @@ struct internal_base {
 	struct ub_event* slow_accept;
 	/** true if slow_accept is enabled */
 	int slow_accept_enabled;
+	/** last log time for slow logging of file descriptor errors */
+	time_t last_slow_log;
 };
 
 /**
@@ -889,6 +891,15 @@ int comm_point_perform_accept(struct comm_point* c,
 				struct timeval tv;
 				verbose(VERB_ALGO, "out of file descriptors: "
 					"slow accept");
+				ub_comm_base_now(b);
+				if(b->eb->last_slow_log+SLOW_LOG_TIME <=
+					b->eb->secs) {
+					b->eb->last_slow_log = b->eb->secs;
+					log_err("accept failed, slow down "
+						"accept for %d msec: %s",
+						NETEVENT_SLOW_ACCEPT_TIME,
+						sock_strerror(errno));
+				}
 				b->eb->slow_accept_enabled = 1;
 				fptr_ok(fptr_whitelist_stop_accept(
 					b->stop_accept));
@@ -909,6 +920,9 @@ int comm_point_perform_accept(struct comm_point* c,
 					/* we do not want to log here,
 					 * error: "event_add failed." */
 				}
+			} else {
+				log_err("accept, with no slow down, "
+					"failed: %s", sock_strerror(errno));
 			}
 			return -1;
 		}

util/netevent.h

@@ -102,6 +102,8 @@ typedef int comm_point_callback_type(struct comm_point*, void*, int,
 
 /** timeout to slow accept calls when not possible, in msec. */
 #define NETEVENT_SLOW_ACCEPT_TIME 2000
+/** timeout to slow down log print, so it does not spam the logs, in sec */
+#define SLOW_LOG_TIME 10
 
 /**
  * A communication point dispatcher. Thread specific.