Mailscanner generated duplicate message.

[Mark Sapiro]

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Mark Sapiro wrote:

| Alex Broens wrote:
|>
|>
|>
|>
|> On 12/24/2007 3:23 PM, Mark Sapiro wrote:
|>> Alex Broens wrote:
|>>> probably totally irrelevant yet got a hunch...
|>>>
|>>>
|>>> what are your settings in MailScanner.conf for
|>>>
|>>> Queue Scan Interval
|>>>
|>>> Max Unscanned Messages Per Scan
|>>>
|>>> Max Unsafe Messages Per Scan
|>>
|>>
|>> Queue Scan Interval = 6
|>>
|>> Max Unscanned Messages Per Scan = 30
|>>
|>> Max Unsafe Messages Per Scan = 30
|>>
|>>
|>>> Could it be you're seeing a race condition between scanning threads?
|>>
|>>
|>> This is exactly what the problem seems to be, but I don't know what to
|>> do to prevent it or what I could have done or omitted to cause it.
|>>
|>> I suppose I could set
|>>
|>> Max Children = 1
|>>
|>> but that seems extreme, and it seems if it were necessary, more than
|>> just me would be seeing this problem.
|>
|> Single CPU:
|>
|> Max Children = 5
|
|
| This is what I currently have.
|
|
|> Dual:
|>
|> Max Children = 8
|>
|> (keep the box relaxed till you get the stuff to process)
|>
|> Pls try:
|>
|> Queue Scan Interval = 15
|>
|> Max Unscanned Messages Per Scan = 5
|> Max Unsafe Messages Per Scan = 5
|
|
| I will try these. Note that I will be offline for the next week, so I
| won't be able to report much until after the new year.


I tried the above settings from Dec 24 through Jan 3. During that
period, I see three more duplication incidents in my maillog. This is a
lower rate than previous, but there are still dups.

As of Jan 3, I have reverted the above settings to their default values,
and set

Max Children = 2

So far, there have been no more dups, but I think it's too early to
tell. Given the load on my system, Max Children = 2 seems fine. If I do
see more dups, I may even try setting it to 1 which I'm certain will
eliminate the problem.


|> You may need to tweek "Queue Scan Interval" to your box's perfomance
|>
|> my rule of thumb:
|>
|> Queue Scan Interval = thread_count + 3
|>
|> keep us posted
|
|
| OK.
|
| Note that logs indicate that this problem has only occurred on mail
| which is not actually scanned because of a 'no' in scan.messages.rules.
| I don't know why this would matter, but it may be significant.
|
| All but one of the occurrences were on outgoing mail from localhost. The
| other one was an incoming message to postmaster. Logs indicate 4 copies
| of this one were delivered and I undoubtedly saw all four but just
| deleted them thinking they were multiple spams
|
| The nature of the server is that outgoing mail is virtually all Mailman
| list posts or forwards of mail, all of which was scanned on the way in.
| I would just as soon not have Postfix hold mail from localhost at all,
| but I haven't figured out how to do that.


- --
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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