Re: ezmlm-list vs ezmlm-issubn on AMD64

On Wed, Aug 30, 2006 at 09:06:07PM -0400, Glen Stewart wrote:
> I had an interesting problem crop up when migrating groups from ezmlm-idx .4x 
> on i686 to 5.x on AMD64...
> 
> After the upgrade, I got lots of reports that people were unable to post to 
> the groups that they owned and were subscribed to.  Upon investigating, I 
> discovered that the ezmlm-list command was able to list the subscriber, but 
> the ezmlm-issubn command didn't acknowledge the subscription.

I can confirm this, and I know why.  All subscribers are hashed down to
a set of 53 directory tables, and ezmlm-idx only looks at one of those
tables to determine if a subscriber exists.  However, it looks at all
tables when listing subscribers.  The problem is that the variable used
to compute the has is declared as an "unsigned long", which is a 64-bit
integer on AMD64 (and any other 64-bit system) but only a 32-bit integer
on ia32.  This results in a differing hash code on different systems.

Here's the problem, however: I can fix that to always use a 32-bit
variable internally, but then any list that was created with the old
version will break with the new version.  I can leave it as-is, and the
problem you describe will continue to happen.  Either way, it's broken.

> What I ended up doing was to use ezmlm-list to dump the members of each group 
> to a text file, delete the original subscriber data files, and rebuild them 
> from scratch using the ezmlm-sub command.  After doing this, ezmlm-issubn AND 
> ezmlm-list seemed to be in sync.

That's the only way to fix it, yes.

> BUT, it appears the problem is creeping back again.  I created a new group 
> yesterday, and see the same address subscribed TWICE, in the same lower-case.

This however should not be possible, unless the list is being accessed
by differing systems.
-- 
Bruce Guenter <[email protected]>                http://untroubled.org/
OpenPGP key: 699980E8 / D0B7 C8DD 365D A395 29DA  2E2A E96F B2DC 6999 80E8
	I do custom software development.  Email me for details.

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