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From "Akins, Brian" <Brian.Ak...@turner.com>
Subject Re: keepalive connections and exiting MPM processes
Date Tue, 13 Nov 2007 17:09:33 GMT
On 11/13/07 8:30 AM, "Jeff Trawick" <trawick@gmail.com> wrote:


>       * Note that the condition evaluation order is extremely important.
> @@ -212,7 +214,8 @@
>          && (!apr_table_get(r->subprocess_env, "nokeepalive")
>              || apr_table_get(r->headers_in, "Via"))
>          && ((ka_sent = ap_find_token(r->pool, conn, "keep-alive"))
> -            || (r->proto_num >= HTTP_VERSION(1,1)))) {
> +            || (r->proto_num >= HTTP_VERSION(1,1)))
> +        && !ap_graceful_stop_signalled()) {
>          int left = r->server->keep_alive_max - r->connection->keepalives;
> 
>          r->connection->keepalive = AP_CONN_KEEPALIVE;

Looks reasonable.

We do so many checks in this function, and it's a pain to modify.  I wish
this were a hook.  I have selfish reasons for this, as I want an easy way to
limit the number of keepalives per child (especially in event mpm).  It
would be so much easier if this were a hook:

In event somewhere:

 static can_http_keepalive(request_rec *r) {
    if (current_num_of_keepalives + 1 > configured_max) {
        return NO; /*whatever, not OK or declined...*/
    }
    return OK;
 }

When resources get tight, I'd like to disable keepalives so I don't have all
the "freeloading" connections hanging around.  (Sometimes every little bit
helps...)

Also, shouldn't Keepalive become HTTPKeepalive and live in the http_module's
config (which doesn't exist, I don't think) rather than is "global"
server_rec.  Keepalive doesn't make sense for mod_ftp, mod_dns, etc.

While I'm thinking about this, shouldn't virtual server selection be a hook
rather than the current "core" way... Would make eventually "dynamic"
server_rec creation easier.


  
-- 
Brian Akins
Chief Operations Engineer
Turner Digital Media Technologies


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