Re: [tlug] Overloaded mail spool causing memory instability?

[Curt Sampson <cjs@example.com>]

On Sat, 18 Aug 2007, Stephen J. Turnbull wrote:

> The question I answered was the one you asked explicitly: "does having
> a large mailbox use up memory?"  The answer is no, for the reasons I
> gave.  [Curt points out that the append may be more complicated, but
> AFAICS it still takes extra memory in proportion to the size of the
> message, not in proportion to the size of the mbox on disk.]

One hopes so, and very likely so. Still, I can think of somewhat
pathological ways of writing delivery agents, mostly related to bad use
of libraries, that might do do badly with large mailbox files. Put it in
the "low probability, but not ruled out" category until you are sure you
know just how mail is delivered to your mboxes.

> I'm not sure about CPU, but it seems to me that performance generally
> degrades gracefully if it's only CPU that's in contention (not RAM or
> net bandwidth).

Darn, Wikipedia doesn't really get into the joys of livelock. But it's
more common than you'd think that lack of CPU leads to a big mess;
usually it just can't serve the offered load, but in an attempt to be
fair it keeps spending a bit of time accepting connections, which causes
it to have less time to serve seach existing connection, the number of
which is growing, and, well, you can see where that goes.

Not that this is necessarially the case here, and IANAL, and etc etc.

cjs
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Curt Sampson       <cjs@example.com>        +81 90 7737 2974
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