Note re memory pressure and the queue shoveller

server/queue.c

@@ -144,6 +144,9 @@ static void shoveller(void *qv) {
   end_burst(q, &burst_count, total_count);
   //info("Waiting for throck\n");
   q->shovel_awake = 0;
+  /* TODO: if the number of active processes is large, assume we have
+     memory pressure, and quit the shovel early rather than waiting
+     for a few milliseconds to see if we're idle. */
   if (nap(100)) {
     cmsg_bytes_t n = sexp_data(q->name);
     info("Queue <<%.*s>> idle. Shoveller exiting\n", n.len, n.bytes);