Status: introduced the "ngx_stat_waiting" counter. And corresponding variable $connections_waiting was added. Previously, waiting connections were counted as the difference between active connections and the sum of reading and writing connections. That made it impossible to count more than one request in one connection as reading or writing (as is the case for SPDY). Also, we no longer count connections in handshake state as waiting.

--- a/src/event/ngx_event.h
+++ b/src/event/ngx_event.h
@@ -511,6 +511,7 @@ extern ngx_atomic_t  *ngx_stat_requests;
 extern ngx_atomic_t  *ngx_stat_active;
 extern ngx_atomic_t  *ngx_stat_reading;
 extern ngx_atomic_t  *ngx_stat_writing;
+extern ngx_atomic_t  *ngx_stat_waiting;
 
 #endif