On Fri, 4 Feb 2000, Omer Efraim wrote:
> Don't forget that on large corporate mail systems quite a lot
> of the cpu load comes from people _checking_ for mail.
> Imagine 10k users, each checking for mail every 5 minutes.
> Each one of those requires a fork even if the user has no (new?) mail.
yes, but the way the pop server works, it still performs these files
copies, no matter if the user eventually downloads their email or not (at
least qpopper used to make a file copy operation immediatly when the
user's mail client sent the user's password, and before returning a reply.
this caused clients to wrongly report of a 'wrong password' on timing out,
rather then reporting on a 'timeout' - that's what happened with pegasus
mail back in 95 or so...
you need to check out how to avoid any kind of file copying operations if
you want an fork() savings to make any sense... the POP protocol is
useless in making such kinds of checks, unless it gets extended in some
manner (e.g. by having a 'LAST_UPDATE command to notify the mail client
when was the user's incoming mailbox last modified. however, this won't
help much, unless _no_ file copy operations are performed if there is no
new mail waiting for the user, relative to the specific client checking
for mail - the user may be reading their email from different
computers...).
now - how do you fix this up? without fixing this up - your "less forking"
system won't be any better then the current system...
> Well, I agree - but this is a whole other symphony and requires much more
> work, and it works on a much larger scale.I myself download mail tunneled
> through ssh so it's compressed anyhow, but I guess it would be nice to
> have clients supporting it out of the box.
you're looking for large scale solutions - your ssh tunneling solution is
not large scale at all.
> Single file. The reasoning
> behind Maildirs was not really performance but rather robustness.
this does not say it cannot be used for gaining in performance as well...
guy
"For world domination - press 1,
or dial 0, and please hold, for the creator." -- nob o. dy
