Re: SRS implemenation in sendmail

Tom Lahti wrote:

> [snip]
>
>> Perhaps in abundance, but spf-milter, as of 1.40, at:
>>
>> http://spf.pobox.com/sendmail-milter-spf-1.41.pl
>>
>> also has full support for "fake DSN detection" (-S), using SRS. A
>> Milter, imho, is really a good place to implement such a policy.
>
> After a week of using sendmail-milter-spf-1.41.pl, I have come to the
> conclusion that it is far from rock solid stable.  It may work for
> long periods on low volume mail servers, but its limitations become
> apparent when you throw some real load at it.
>
> The sendmail-milter-spf does not handle this kind of volume.  The
> first thing I noticed is the memory leaks.  The RSS of the process
> slowly climbs.  I wrote a script that runs from cron and checks on it
> and when it gets to 80MB it restarts.  That is currently happening
> about once every 21 hours.

I think this is actually a Perl problem itself. I have a similar problem on
a news server in Perl. It seems memory occupied by strings, especially
hashes, gets poorly freed, even if you specifically delete or undef the
content.

spf-milter will always grow a bit since startup, btw. It could grow with max
64K segments (for body chunks), times the amount of pending connections.
Those spurts would be temporary, though. Memory, as in my news server,
really seems to get lost over time as deleted hash-space is not freed up. I
have yet to find a solution for that.

When perl 5.8.0 was released, it leaked memory like crazy, especially using
ithreads. It is better in 5.8.4, but remains an issue. There are, as far as
I can tell, no identifiable, obvious places in spf-milter where memory is
not freed where it should have been. All private per-connection data gets
destroyed at close_callback: $ctx -> setpriv (undef); it may very well be
that Sendmail::Milter itself leaks the memory.


> The second thing is it dies periodically.

This has not yet happened to me; you are the first to report this. So I
cannot comment on why this would occur.

- Mark

        System Administrator Asarian-host.org

---
"If you were supposed to understand it,
we wouldn't call it code." - FedEx