Re: Arghh, my Gnus is going crazy !!

[Kevin Greiner <kevin.greiner@vignette.com>]

Xavier Maillard <zedek@gnu-rox.org> writes:

> Hello,
>
> Dunno what is going on on Gnus but I have *HUGE* troubles since
> yesterday and my latest upgrade (No Gnus).
>
> Whenever I try to enter a USENET group, Gnus complains about
> 'duplucate line in overview file' and delete all entry from the
> file.
>
> This makes disappearing all the group articles (cached or not,
> downloaded or not) and the group remains empty.
>
> Deleting the .agentview, .overview and doing C-k in the summary
> buffer fix the problem when I resubscribe to the group. Problem
> is that this reappear when I next enter the group.
>
> I checked the famous .overview file and here is a diff on it.
> Quite weird:
>
> ,----
> |  diff -u .overview\~1\~ .overview | more                                                                                                                [1.29 1.30 - 58% 3%]
> | --- .overview~1~        2004-09-25 14:21:52 +0200
> | +++ .overview   2004-09-25 14:21:52 +0200
> | @@ -1,1081 +1,811 @@
> |  794    Re: Facturation : Avoir raph <fraph@free.fr>    Thu, 08 Jul 2004 09:05:07 +0200 <opsas4mtkyosm168@news.nerim.net>       <ccgrk3$ish$1@biggoron.nerim.net>       2473 47       Xref: news.gnu-rox.org nerim.support:794
> | -794    Re: Facturation : Avoir raph <fraph@free.fr>    Thu, 08 Jul 2004 09:05:07 +0200 <opsas4mtkyosm168@news.nerim.net>       <ccgrk3$ish$1@biggoron.nerim.net>       2473 47       Xref: news.gnu-rox.org nerim.support:794
> | -795    Re: Facturation : Avoir Dominique ROUSSEAU <domi@nerim.net>     Thu, 8 Jul 2004 09:52:09 +0200  <9fuicc.ej3.ln@127.0.0.1>       <ccgrk3$ish$1@biggoron.nerim.net> <ops
> | as4mtkyosm168@news.nerim.net>   1571    25      Xref: news.gnu-rox.org nerim.support:795
> | +794795 Re: Facturation : Avoir Dominique ROUSSEAU <domi@nerim.net>     Thu, 8 Jul 2004 09:52:09 +0200  <9fuicc.ej3.ln@127.0.0.1>       <ccgrk3$ish$1@biggoron.nerim.net> <ops
> | as4mtkyosm168@news.nerim.net>   1571    25      Xref: news.gnu-rox.org nerim.support:795
> |  795
> `----
>
> Something is doing concatenation somewhere (look 794, 795 and the
> 794795). What is that ????
>
> Thank you for any hint on fixing this.

This is actually a very old problem. We've made very little progress
with it, hence the gnus-agent-check-overview-buffer function, as it is
rarely reproducable.  I suspect that the actual bug is in your server
and that it is sending you bad headers.

Let's try this first:

Delete the group's .overview and .agentview so that you fetch all new
headers from nntp.

Customize nntp-nov-is-evil to set it to t.  Try to open the group, if
the problem has gone away then we know that your server's nov database
is corrupt.

If that doesn't fix it, would you be willing to do a little debugging
for me?

If so, please do the following.

Then do
M-x load-library<ret>gnus-agent.el<ret>
M-x gnus
M-x debug-on-entry<ret>gnus-agent-check-overview-buffer<ret>

Now try to open the group's summary buffer.  This should launch the
debugger.

If I've gotten this right, the stack trace should show that
gnus-agent-check-overview-buffer was called by
gnus-agent-fetch-headers.  The current buffer should contain the raw
headers returned by nntp.  How do they look?  If they look fine, the
likely culpret is the gnus-agent-braid-nov function it is about to
be called so you can just step forward from here to watch it
execute.  If that is too much to ask, you can also save the nntp
headers (the entire buffer) to a file then email it to me.  I'll
fool my gnus into parsing those headers which should let me
reproduce the bug.

Kevin