Don't delete timer of write event when it's delayed.

[Maxim Dounin]

Hello!

On Wed, Dec 27, 2023 at 10:56:44AM +0800, Jiuzhou Cui wrote:

> Hello!
> 
> 
> # HG changeset patch
> # User Jiuzhou Cui <cuijiuzhou at alibaba-inc.com>
> # Date 1703645578 -28800
> #      Wed Dec 27 10:52:58 2023 +0800
> # Node ID 474ae07e47272e435d81c0ca9e4867aae35c30ab
> # Parent  ee40e2b1d0833b46128a357fbc84c6e23be9be07
> Don't delete timer of write event when it's delayed.
> 
> 
> This will make download speed alway zero when limit_rate in body filter.
> 
> 
> diff -r ee40e2b1d083 -r 474ae07e4727 src/http/ngx_http_upstream.c
> --- a/src/http/ngx_http_upstream.c      Mon Dec 25 21:15:48 2023 +0400
> +++ b/src/http/ngx_http_upstream.c      Wed Dec 27 10:52:58 2023 +0800
> @@ -3787,11 +3787,13 @@
>          }
>      }
> 
> 
> -    if (downstream->write->active && !downstream->write->ready) {
> -        ngx_add_timer(downstream->write, clcf->send_timeout);
> -
> -    } else if (downstream->write->timer_set) {
> -        ngx_del_timer(downstream->write);
> +    if (!downstream->write->delayed) {
> +        if (downstream->write->active && !downstream->write->ready) {
> +            ngx_add_timer(downstream->write, clcf->send_timeout);
> +
> +        } else if (downstream->write->timer_set) {
> +            ngx_del_timer(downstream->write);
> +        }
>      }
> 
> 
>      if (upstream->read->eof || upstream->read->error) {

Thank you for the patch.

You are patching the 
ngx_http_upstream_process_non_buffered_request() function, which 
is, as can be correctly concluded from the function name, is used 
for non-buffered proxying.  Non-buffered proxying is specifically 
designed to return responses as long as they are available, and is 
not compatible with limit_rate.  Moreover, limit_rate is 
explicitly disabled in the ngx_http_upstream_send_response() 
function when the relevant handers are set:

        u->read_event_handler = ngx_http_upstream_process_non_buffered_upstream;
        r->write_event_handler =
                             ngx_http_upstream_process_non_buffered_downstream;

        r->limit_rate = 0;
        r->limit_rate_set = 1;

(https://hg.nginx.org/nginx/file/release-1.25.3/src/http/ngx_http_upstream.c#l3092)

As such, the issue you are trying to fix is not expected to 
appear.

Could you please clarify the configuration you are seeing the 
issue with, and steps to reproduce the issue?

-- 
Maxim Dounin
http://mdounin.ru/