busy_lock        2682 http/ngx_http_upstream.c             ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
busy_lock        2795 http/ngx_http_upstream.c     ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
busy_lock        2894 http/ngx_http_upstream.c     if (u->conf->busy_lock && !u->busy_locked) {