[core] restart dead piped loggers every 64 sec

(when piped logger exited too quickly after being restarted
 and when server.max-worker = 0)

src/fdevent.c

@@ -875,7 +875,7 @@ int fdevent_reaped_logger_pipe(pid_t pid) {
             if (fcp->start + 5 < ts) { /* limit restart to once every 5 sec */
                 fcp->start = ts;
                 fcp->pid = fdevent_open_logger_pipe_spawn(fcp->cmd,fcp->fds[0]);
-                return 1;
+                return (fcp->pid > 0) ? 1 : -1;
             }
             else {
                 fcp->pid = -1;

src/server.c

@@ -1423,8 +1423,13 @@ static void server_handle_sigalrm (server * const srv, time_t min_ts, time_t las
 				}
 			      #endif
 
-				/* free excess chunkqueue buffers every 64 seconds */
-				if (0 == (min_ts & 0x3f)) chunkqueue_chunk_pool_clear();
+				if (0 == (min_ts & 0x3f)) { /*(once every 64 secs)*/
+					/* free excess chunkqueue buffers every 64 secs */
+					chunkqueue_chunk_pool_clear();
+					/* attempt to restart dead piped loggers every 64 secs */
+					if (0 == srv->srvconf.max_worker)
+						fdevent_restart_logger_pipes(min_ts);
+				}
 				/* cleanup stat-cache */
 				stat_cache_trigger_cleanup();
 				/* reset global/aggregate rate limit counters */