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Subject: Re: Behaviour of mod_proxy_ajp if CPING/CPONG fails
Date: Fri, 5 Sep 2008 17:34:20 +0200
Message-ID: 
 <99EA83DCDE961346AFA9B5EC33FEC08B011B9D3F@VF-MBX11.internal.vodafone.com>
In-Reply-To: <48C14B22.4000003@apache.org>
Thread-Topic: Re: Behaviour of mod_proxy_ajp if CPING/CPONG fails
Thread-Index: AckPaTGChbL53/DnQfmeiI8ojbQmdgAAsuTA
References: 
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 <48C14B22.4000003@apache.org>
From: =?iso-8859-1?Q?=22Pl=FCm=2C_R=FCdiger=2C_VF-Group=22?=
 <ruediger.pluem@vodafone.com>
To: <dev@httpd.apache.org>

=20

> -----Urspr=FCngliche Nachricht-----
> Von: Mladen Turk=20
> Gesendet: Freitag, 5. September 2008 17:07
> An: dev@httpd.apache.org
> Betreff: Re: Behaviour of mod_proxy_ajp if CPING/CPONG fails
>=20
> Pl=FCm, R=FCdiger, VF-Group wrote:
>=20
> > So after the first failed CPING/CPONG we should try again=20
> with a new TCP connection
> > and should only return HTTP_SERVICE_UNAVAILABLE if this=20
> fails as well. The following
> > (and attached patch) does exactly that. Thoughs to the=20
> above and/or to the patch
> > before I commit?
> >
>=20
> +1 for the concept.
> However for threaded servers you should call
> ap_proxy_acquire_connection inside retry loop, cause there might
> be available connections inside the pool.

I don't think that this does what you want. If I simply continue to
acquire connections from the pool without returning the faulty ones
back before, other threads might starve because they cannot get =
connections
from the reslist any longer (not even faulty ones, that they would =
reopen).
If I return the faulty connection to the reslist, there is some =
likelyhood
that I get the same connection back within the next acquire as the =
reslist
is organized as a stack. IMHO this approach would only work if the =
reslist
was organized as a queue, which it is no longer in order to get the ttl
feature in conjunction with smax working correctly.

Regards

R=FCdiger