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Subject: Re: 1012 noops in a row cause slow responses from Postfix.
From: Wietse Venema (wietseporcupine.org)
Date: Fri Jun 23 2000 - 16:40:29 CDT

Mark Hoffman:
> I set the service to noop every 2 seconds to reproduce the problem.
>
> I guess the real problem is that even after a successful delivery, the
> response is still slow. We are seeing this behavior even while sending email
> in the middle of the 1012 noops. i.e. If we send 500 noops, then an email,
> Then more noops, response gets slow at ~1030 noops total. So it seems the
> successful email doesn't reset the session record, when a constant
> connection is maintained.

Successful delivery resets the session recording.

Successful delivery does NOT reset the junk command counter.

> In our production environment, we see this behavior after ~ 3 days. Granted,
> NT usually has to be rebooted more often than that, but I've finally gotten
> my service to run for a couple of weeks at a stretch. And, because of the
> load on the gateways between the NT servers and the Postfix servers, I want
> to noop to make sure the connection is still there before sending mail.

Why bother keeping the connection open?

If you send 1000 NOOPs in 3 days, that means your NT client makes
less than one delivery every four minutes.

        Wietse