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Date: Sat, 19 Apr 2014 16:26:53 -0400
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 <CALK=YjOTMAm+DA-HV0y0ntuxq5VnTQ6vA6W_Ao03BLNBOkOcbA@mail.gmail.com>
Subject: Re: mod_cache thundering herd bug
From: Eric Covener <covener@gmail.com>
To: Apache HTTP Server Development List <dev@httpd.apache.org>
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On Tue, Apr 8, 2014 at 4:11 PM, Jim Riggs <apache-lists@riggs.me> wrote:
> https://issues.apache.org/bugzilla/show_bug.cgi?id=3D50317
>
> While we are at ApacheCon, I would love to address this nasty bug with so=
meone familiar with 2.2's mod_cache. Our sites were brought down a few time=
s last year before we finally tracked it down to being this particular bug.=
 I am using a crude backport of the 2.3 patch (r1023398) in 2.2. It works, =
but I don't know if it is correct.
>
> Can someone look at this one with me? We really need to get this fixed in=
 2.2, because there is NO thundering herd protection at all as things stand=
 right now.
>


Graham -- related subject brought up either in Denver or in the bug.
It seems that when we serve a stale file while the cache is locked,
the age headers are small instead of large. I got totally lost trying
to track down the issue, maybe it makes sense to you?  It's almost as
if they time of the revalidation is somehow updated early and the
delta in the stale cache hits is based off of that.

--=20
Eric Covener
covener@gmail.com