Clarify maxclients and cluster in conf. Remove myself too.

redis.conf

@@ -805,6 +805,11 @@ acllog-max-len 128
 # Once the limit is reached Redis will close all the new connections sending
 # an error 'max number of clients reached'.
 #
+# IMPORTANT: When Redis Cluster is used, the max number of connections is also
+# shared with the cluster bus: every node in the cluster will use two
+# connections, one incoming and another outgoing. It is important to size the
+# limit accordingly in case of very large clusters.
+#
 # maxclients 10000
 
 ############################## MEMORY MANAGEMENT ################################

src/cluster.c

@@ -694,8 +694,11 @@ void clusterAcceptHandler(aeEventLoop *el, int fd, void *privdata, int mask) {
 /* Return the approximated number of sockets we are using in order to
  * take the cluster bus connections. */
 unsigned long getClusterConnectionsCount(void) {
+    /* We decrement the number of nodes by one, since there is the
+     * "myself" node too in the list. Each node uses two file descriptors,
+     * one incoming and one outgoing, thus the multiplication by 2. */
     return server.cluster_enabled ?
-           (dictSize(server.cluster->nodes)*2) : 0;
+           ((dictSize(server.cluster->nodes)-1)*2) : 0;
 }
 
 /* -----------------------------------------------------------------------------