Upstream: the "zone" directive.

Upstreams with the "zone" directive are kept in shared memory,
with a consistent view of all worker processes.

auto/modules

diff --git a/auto/modules b/auto/modules
index 5a56957..a029cdd 100644
--- a/auto/modules
+++ b/auto/modules
@@ -391,6 +391,12 @@
     HTTP_SRCS="$HTTP_SRCS $HTTP_UPSTREAM_KEEPALIVE_SRCS"
 fi
 
+if [ $HTTP_UPSTREAM_ZONE = YES ]; then
+    have=NGX_HTTP_UPSTREAM_ZONE . auto/have
+    HTTP_MODULES="$HTTP_MODULES $HTTP_UPSTREAM_ZONE_MODULE"
+    HTTP_SRCS="$HTTP_SRCS $HTTP_UPSTREAM_ZONE_SRCS"
+fi
+
 if [ $HTTP_STUB_STATUS = YES ]; then
     have=NGX_STAT_STUB . auto/have
     HTTP_MODULES="$HTTP_MODULES ngx_http_stub_status_module"

auto/options

diff --git a/auto/options b/auto/options
index 763871f..7a3909a 100644
--- a/auto/options
+++ b/auto/options
@@ -103,6 +103,7 @@
 HTTP_UPSTREAM_IP_HASH=YES
 HTTP_UPSTREAM_LEAST_CONN=YES
 HTTP_UPSTREAM_KEEPALIVE=YES
+HTTP_UPSTREAM_ZONE=YES
 
 # STUB
 HTTP_STUB_STATUS=NO
@@ -256,6 +257,7 @@
         --without-http_upstream_least_conn_module)
                                          HTTP_UPSTREAM_LEAST_CONN=NO ;;
         --without-http_upstream_keepalive_module) HTTP_UPSTREAM_KEEPALIVE=NO ;;
+        --without-http_upstream_zone_module) HTTP_UPSTREAM_ZONE=NO  ;;
 
         --with-http_perl_module)         HTTP_PERL=YES              ;;
         --with-perl_modules_path=*)      NGX_PERL_MODULES="$value"  ;;
@@ -406,6 +408,8 @@
                                      disable ngx_http_upstream_least_conn_module
   --without-http_upstream_keepalive_module
                                      disable ngx_http_upstream_keepalive_module
+  --without-http_upstream_zone_module
+                                     disable ngx_http_upstream_zone_module
 
   --with-http_perl_module            enable ngx_http_perl_module
   --with-perl_modules_path=PATH      set Perl modules path

auto/sources

diff --git a/auto/sources b/auto/sources
index bcadf6a..021a767 100644
--- a/auto/sources
+++ b/auto/sources
@@ -513,6 +513,11 @@
     src/http/modules/ngx_http_upstream_keepalive_module.c"
 
 
+HTTP_UPSTREAM_ZONE_MODULE=ngx_http_upstream_zone_module
+HTTP_UPSTREAM_ZONE_SRCS=" \
+    src/http/modules/ngx_http_upstream_zone_module.c"
+
+
 MAIL_INCS="src/mail"
 
 MAIL_DEPS="src/mail/ngx_mail.h"