Increased the default number of output buffers.

Since an output buffer can only be used for either reading or sending, small
amounts of data left from the previous operation (due to some limits) must be
sent before nginx will be able to read further into the buffer.  Using only
one output buffer can result in suboptimal behavior that manifests itself in
forming and sending too small chunks of data.  This is particularly painful
with SPDY (or HTTP/2) where each such chunk needs to be prefixed with some
header.

The default flow-control window in HTTP/2 is 64k minus one bytes.  With one
32k output buffer this results is one byte left after exhausting the window.
With two 32k buffers the data will be read into the second free buffer before
sending, thus the minimum output is increased to 32k + 1 bytes which is much
better.

diff --git a/src/http/ngx_http_copy_filter_module.c b/src/http/ngx_http_copy_filter_module.c
index 0f908add7150e86f29c9c9e70c0739d8053fd62b..c6d03eec0bc4a7eb13acf63a5cb20ee9cd1c0899 100644 (file)
--- a/src/http/ngx_http_copy_filter_module.c
+++ b/src/http/ngx_http_copy_filter_module.c
@@ -327,7 +327,7 @@ ngx_http_copy_filter_merge_conf(ngx_conf_t *cf, void *parent, void *child)
     ngx_http_copy_filter_conf_t *prev = parent;
     ngx_http_copy_filter_conf_t *conf = child;
 
-    ngx_conf_merge_bufs_value(conf->bufs, prev->bufs, 1, 32768);
+    ngx_conf_merge_bufs_value(conf->bufs, prev->bufs, 2, 32768);
 
     return NULL;
 }