--- a/src/http/ngx_http_write_filter.c
+++ b/src/http/ngx_http_write_filter.c
@@ -7,6 +7,9 @@
 
 typedef struct {
     ngx_chain_t  *out;
+
+ /* unsigned      flush:1; */
+    ngx_uint_t    flush;
 } ngx_http_write_filter_ctx_t;
 
 
@@ -42,7 +45,6 @@ ngx_int_t ngx_http_write_filter(ngx_http
     int                           last;
     off_t                         size, flush, sent;
     ngx_chain_t                  *cl, *ln, **ll, *chain;
-    ngx_http_core_srv_conf_t     *cscf;
     ngx_http_core_loc_conf_t     *clcf;
     ngx_http_write_filter_ctx_t  *ctx;
 
@@ -114,7 +116,7 @@ ngx_int_t ngx_http_write_filter(ngx_http
         return NGX_AGAIN;
     }
 
-    if (size == 0) {
+    if (size == 0 && !ctx->flush) {
         if (!last) {
             ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                           "the http output chain is empty");
@@ -124,11 +126,8 @@ ngx_int_t ngx_http_write_filter(ngx_http
 
     sent = r->connection->sent;
 
-    cscf = ngx_http_get_module_srv_conf(r, ngx_http_core_module);
-
-    chain = cscf->send_chain(r->connection, ctx->out,
-                             clcf->limit_rate ? clcf->limit_rate:
-                                                OFF_T_MAX_VALUE);
+    chain = r->send_chain(r->connection, ctx->out,
+                          clcf->limit_rate ? clcf->limit_rate: OFF_T_MAX_VALUE);
 
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                    "http write filter %X", chain);
@@ -144,6 +143,12 @@ ngx_int_t ngx_http_write_filter(ngx_http
         return NGX_ERROR;
     }
 
+    if (chain == NGX_CHAIN_AGAIN) {
+        ctx->out = NULL;
+        ctx->flush = 1;
+        return NGX_AGAIN;
+    }
+
     ctx->out = chain;
 
     if (chain == NULL) {