subrequest in limit_rate

Wu Bingzheng wubingzheng at
Mon Nov 1 12:40:59 MSK 2010

Hi all,
Does limit_rate, which is in write filter module, work right when many subrequests exist?
I meet a problem with limit_rate for many subrequests. Here is the problem.
1. limit_rate works like this:
a) after sending data, it will set wev->delayed which disable data sending, and sleep for a while(add_timer);
b) when timedout, the wev handler will clear wev->delayed, to enable data sending.
For example, the handler may like this;


  2361    if (wev->timedout) {

  2363        if (wev->delayed) {

  2367            wev->delayed = 0;

  2389        }

  2395    }

2. but 1 wev (write event) corresponds to 1 connection; while 1 (downstream) connection may has many subrequests.
so when wev timedout, wev gets the active request of the connection, like this:


  1724    c = ev->data;

  1725    r = c->data;


  1733    if (ev->write) {

  1734        r->write_event_handler(r);

  1737    } else {

  1738        r->read_event_handler(r);

  1739    }



3. The problem is that: the active request of this connection maybe not the one who added the timer. which means that the active request of the connection changes before timedout. So its write_event_handler maybe not the one expected. For example, if the active request's write_event_handler is happened to be ngx_http_request_empty_handler(), which is set in ngx_http_core_content_phase(), then the handler doesn't clear the wev->delayed.So the data sending in write filter module will never be enabled again.


Is my analysis right? Does limit_rate work right for many subrequests?


I hope I made myself understood.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the nginx mailing list