[svlug] Fw: MICROSOFT ACQUIRES LINUX OPERATING SYSTEM

[Javilk]

> On Sun, 15 Nov 1998, Javilk wrote:
> 
> >     That would get rather bad!  Why doesn't sendmail run multiples at
> > once?
> 
> When sendmail collects a new email, it is normally configured to deliver
> immediately. If 10 emails come it, it can fork off 10 processes to deliver
> them. If a delivery fails, it is queued. Sendmail will also queue rather
> than deliver if the system load is too high. If you send a lot of mail to

    That all sounds quite sensible.  That is the way I would have written
it.   

     In my case, I have three classes of mailings.  The heavy stuff is a
string of heavy compute jobs, each spawning elm to kick the results into
the mail queue. I often stay up and watch this one grind away, as the
recipients are depending on the results. (This isn't spamming, they pay me
for the results.  Not enough...) 

     Next, there are the first class mailing lists, as I call them, where
computationally heavy tasks generates the text, and light tasks determine
who should be notified of the results.  Each one gets an individual
mailing via elm.  This one jams fairly quickly if not paced. It once built
up enough load that the individual elm steps started failing, which is why
I added the three second delay. (Losing these makes me Very nervous!)

     Even worse, is when spam filters on some sites mistakenly block
these, and the subscribers start complaining they are not getting what
they are paying for.  We had to go through three ISP's with one of the
subscribers before he could get his reports!  He's paying the ISP more
than he is paying me!  And that report is addressed directly to him, not
through a mailing list. 

     And the third, are the mailing lists, where a single heavy compute
job generates a large block of text, and elm kicks it to a subscriber list
via the /etc/aliases file. (Some lists are paid, some are free.)

     What does happen when I feed sendmail something addressed to an
/etc/aliases mailing list via elm?  Does it send each one individually, or
pass the entire list to an upline mail handler though my puny modem link?
 
     Is elm a reasonable way of kicking e-mail into the mail queue?  Is
there any way of pushing more of the sending load upline to my ISP?  Some
of these compute tasks just peg the CPU meter, and I am trying to rig
stuff to use multiple machines to speed up processing.  These reports
often keep me up all night when I run them. 

> a particular domain ... say company headquarters or AOL and that site is
> down, the child process that was forked off to deliver it will time out
> and the message will be queued. Lets say that over the course of an hour
> you have 100 of these. On the next queue run, sendmail will sequentially
> process them. If the site is still down, each message will time out ( 5
> minutes per message). 100 messages * 5 minutes/message = 500 minutes to
> run through the queue one time.

    I see... so what one wants, is to start spawning again while
processing the queue when the load drops. Perhaps I should stick a few
sendmail -q &'s in at the end of the job that does all this to help mop up
the aftermath. 

> Going back to the first example ... when handling a large volume of mail,
> often the load level goes high enough to force it to queue mail, some
> remote sites will defer mail for various reasons etc. Once mail is in the
> queue, it can take forever to get out. In other words, if sendmail can not
> deliver it immediately, it might be a long time to deliver it.

   I see.  So the crontab'd senmail -q is a valid way of making sure
several sendmails are working on the task.  How many active sendmail's
would be reasonable on a P200 with 64 meg RAM?  (I've already got swap,
temp and var on separate drives, and rig things to read from one drive and
write to another. Swap shares the same drive with Home.  That speeded
things by about three fold.  Lots of sorting!  I figured the number of
head seeks would be significantly less by sorting, instead of using a
database.  And the disk space, too, since the records are quite variable
in length.  I wouldn't DARE do this on an NT!)

- javilk at mall-net.com -----------------------------
-------- MS asks "Where do you want to go?" -------
------- Linux asks "What do you want to do?" ------
-- It is doers, not goers, who built this world! --
--------- Member: http://www.svlug.org/ -----------

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