Decrease the amount of rend circ relaunches for hidden services.

changes/bug11447

@@ -0,0 +1,5 @@
+  o Minor features (DoS-resistance):
+    - Decrease the amount of reattempts that a hidden service is
+      willing to perform when its rendezvous circuits fail. This
+      reduces the computational cost for hidden service under heavy
+      load. Resolves ticket #11447.

src/or/rendservice.c

@@ -90,7 +90,7 @@ typedef struct rend_service_port_config_t {
 #define MAX_INTRO_CIRCS_PER_PERIOD 10
 /** How many times will a hidden service operator attempt to connect to
  * a requested rendezvous point before giving up? */
-#define MAX_REND_FAILURES 8
+#define MAX_REND_FAILURES 1
 /** How many seconds should we spend trying to connect to a requested
  * rendezvous point before giving up? */
 #define MAX_REND_TIMEOUT 30