ngx_http_keepalive_handler() is now trying to not keep c->buffer's memory for
idle connections.

This behaviour is consistent with the ngx_http_set_keepalive() function and it
should decrease memory usage in some cases (especially if epoll/rtsig is used).

src/http/ngx_http_request.c

diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index ec9d4a1..ef010ff 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -2753,6 +2753,20 @@
             ngx_http_close_connection(c);
         }
 
+        /*
+         * Like ngx_http_set_keepalive() we are trying to not hold
+         * c->buffer's memory for a keepalive connection.
+         */
+
+        if (ngx_pfree(c->pool, b->start) == NGX_OK) {
+
+            /*
+             * the special note that c->buffer's memory was freed
+             */
+
+            b->pos = NULL;
+        }
+
         return;
     }