Fwd: mod_proxy question -- keep-alive teardowns

[Chuck Murcko <ch...@topsail.org>]

I'm looking to commit this in the 1.3.21-dev and module-1.0 code. Any 
other +1?

The problem: httpd 1.3.x does not close origin server proxy connections 
when client connection closes (perhaps pathologically).

Chuck

Begin forwarded message:

> From: Steve Barber <sb...@randomwalk.com>
> Date: Mon Jul 23, 2001  05:33:32 PM US/Eastern
> To: Chuck Murcko <ch...@topsail.org>
> Subject: Re: mod_proxy question -- keep-alive teardowns
>
> Chuck --
>
> I found the bug. Nothing to do with keep-alives. The interesting thing 
> is that
> this problem shouldn't manifest itself if proxy caching is turned on; 
> it will
> only show up if cacheing is off, as it was in our environment.
>
> The 2.0 proxy source looks like it won't have the problem, but that was 
> just a
> cursory glance on my part.
>
> See Apache PR mod_proxy/8067 for details.
>
> I think the fix is:
>
> --- src/modules/proxy/proxy_util-old.c  Mon Jul 23 14:18:31 2001
> +++ src/modules/proxy/proxy_util.c      Mon Jul 23 14:21:40 2001
> @@ -605,6 +605,8 @@
>                          unlink(c->tempfile);
>                         c = NULL;
>                      }
> +                } else {
> +                    ok = 0;
>                  }
>                  con->aborted = 1;
>                  break;
>
> -Steve Barber
>
> Chuck Murcko wrote:
>
>> Wow. 8^)
>>
>> I'd tend to think the proxy should drop its associated (possibly
>> persistent) server connections when the client connection goes away.
>> We're not pooling connections yet in the proxy.
>>
>> I'll look at the 1.3.20 source and the rewrite of mod_proxy for 1.3.21
>> (not yet released, but in anonCVS under httpd-proxy module, it does
>> HTTP/1.1 server-side at last, still HTTP/1.0 client, and will likely
>> remain that way) to see if they are checking the client connection, or
>> just stuck in blocking reads or something. Come to think of it, the 2.0
>> proxy needs a look too. 8^)
>>
>> Yes, we know some of the same ex-Rabbits. You run the mailing list,
>> right?
>>
>> This doesn't sound like a job for mod_backhand, or I'd suggest trying
>> that, as well.
>>
>> Don't worry too much about 1.3 once the bugs are fixed; 2.0 is
>> completely different.
>>
>> Regards,
>> Chuck
>>
>> On Tuesday, July 17, 2001, at 02:28 PM, Steve Barber wrote:
>>
>>> Chuck --
>>>
>>> Can I ask you a question about mod_proxy?
>>>
>>> I've got client and server programs that serialize Java objects over
>>> HTTP. Not only that, but we push async messages from the server to the
>>> client by having the client keep a keep-alive POST request outstanding
>>> (with logic to re-POST whenever the connection gets killed for 
>>> whatever
>>> reason).
>>>
>>> All this is a bit unholy to be sure, but it's a remarkably effective 
>>> way
>>> to be able to deploy complex Java apps that need the server to push
>>> dynamic updates across the public Internet without having users worry
>>> much about those pesky firewalls and other arbitrary corporate 
>>> security
>>> measures.
>>>
>>> I'm having a problem when using Apache 1.3.x (I've tried 1.3.12 on
>>> Win2k, Solaris 7, and Linux and 1.3.20 on Win2k) as an HTTP proxy 
>>> server
>>> using mod_proxy. If my client application gets terminated with extreme
>>> prejudice, the Apache proxy keeps the server-->proxy connection 
>>> intact,
>>> even though the proxy-->client connection is long gone. Our server 
>>> sends
>>> periodic hearbeat messages on this connection; it seems like the 
>>> Apache
>>> proxy is just gleefully bit-bucketing them. I can send stuff all day
>>> long and the "dead" connection never goes away, fooling our server 
>>> into
>>> thinking the client is still alive.
>>>
>>> Here's the question: is this an Apache/mod_proxy bug or a feature? 
>>> That
>>> is, should the Apache proxy at some point notice that the client went
>>> away and tear down the proxy-->server connection so that subsequent
>>> writes by my server to the response stream fail?
>>>
>>> I don't have this problem when I test with the iPlanet Web Proxy 3.6; 
>>> it
>>> seems to tear down the connections nicely.
>>>
>>> Thanks if you can answer this; thanks in advance for your time in any
>>> case. Apologies in advance for not being an HTTP/keep-alive/Apache
>>> expert; I'm working on that.
>>>
>>> -Steve Barber
>>>
>>> P.S. I don't think we know each other, but we know a bunch of the same
>>> folks; I worked at Rabbit Software from '84-'90.
>>>
>>>
>>>
>>>
>>
Chuck Murcko
Topsail Group
http://www.topsail.org/
>
>