--- a/src/event/ngx_event_pipe.c
+++ b/src/event/ngx_event_pipe.c
@@ -254,7 +254,6 @@ int ngx_event_pipe_read_upstream(ngx_eve
                 p->upstream_eof = 1;
                 break;
             }
-
         }
 
         p->read_length += n;
@@ -269,7 +268,7 @@ int ngx_event_pipe_read_upstream(ngx_eve
             if (n >= size) {
                 cl->hunk->last = cl->hunk->end;
 
-/* STUB */ cl->hunk->num = p->num++;
+                /* STUB */ cl->hunk->num = p->num++;
 
                 if (p->input_filter(p, cl->hunk) == NGX_ERROR) {
                     return NGX_ABORT;
@@ -288,7 +287,9 @@ int ngx_event_pipe_read_upstream(ngx_eve
     }
 
     if ((p->upstream_eof || p->upstream_error) && p->free_raw_hunks) {
-/* STUB */ p->free_raw_hunks->hunk->num = p->num++;
+
+        /* STUB */ p->free_raw_hunks->hunk->num = p->num++;
+
         if (p->input_filter(p, p->free_raw_hunks->hunk) == NGX_ERROR) {
             return NGX_ABORT;
         }
@@ -326,9 +327,39 @@ int ngx_event_pipe_write_to_downstream(n
             return ngx_event_pipe_drain_chains(p);
         }
 
-        if ((p->upstream_eof || p->upstream_error || p->upstream_done)
-            && p->out == NULL && p->in == NULL)
-        {
+        if (p->upstream_eof || p->upstream_error || p->upstream_done) {
+
+            /* pass the p->out and p->in chains to the output filter */
+
+            if (p->out) {
+                ngx_log_debug0(NGX_LOG_DEBUG_EVENT, p->log, 0,
+                               "pipe write downstream flush out");
+
+                if (p->output_filter(p->output_ctx, p->out) == NGX_ERROR) {
+                    p->downstream_error = 1;
+                    return ngx_event_pipe_drain_chains(p);
+                }
+
+                p->out = NULL;
+            }
+
+            if (p->in) {
+                ngx_log_debug0(NGX_LOG_DEBUG_EVENT, p->log, 0,
+                               "pipe write downstream flush in");
+
+                if (p->output_filter(p->output_ctx, p->in) == NGX_ERROR) {
+                    p->downstream_error = 1;
+                    return ngx_event_pipe_drain_chains(p);
+                }
+
+                p->in = NULL;
+            }
+
+            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, p->log, 0,
+                           "pipe write downstream done");
+
+            /* TODO: free unused hunks */
+
             p->downstream_done = 1;
             break;
         }
@@ -338,8 +369,9 @@ int ngx_event_pipe_write_to_downstream(n
         }
 
         /*
-         * bsize is the busy hunks size
-         * to_write is the size of data that to be written
+         * bsize is the size of the busy hunks,
+         * to_write is the size of data in these hunks that
+         * would be written to a socket
          */
 
         bsize = 0;
@@ -390,25 +422,24 @@ int ngx_event_pipe_write_to_downstream(n
         }
 
         if (out == NULL) {
+
             ngx_log_debug1(NGX_LOG_DEBUG_EVENT, p->log, 0,
-                           "pipe busy hunk data: %d", to_write);
+                           "pipe busy hunk data to write: %d", to_write);
 
             if (!(p->upstream_blocked && to_write)) {
                 break;
             }
 
-            /*
-             * if the upstream is blocked and there are the busy hunks
-             * to write then write these hunks
-             */
         }
 
+        /*
+         * if the upstream is blocked and there are the busy hunks
+         * to write then write these hunks
+         */
+
         if (p->output_filter(p->output_ctx, out) == NGX_ERROR) {
             p->downstream_error = 1;
-
-            /* handle the downstream error at the begin of a cycle */
-
-            continue;
+            return ngx_event_pipe_drain_chains(p);
         }
 
         ngx_chain_update_chains(&p->free, &p->busy, &out, p->tag);