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               LittleBITS: Why You Got Multiple Copies Last Week

   Adam Engst

   My apologies to those who received multiple copies of last week's
   TidBITS issue! As-yet-unexplained problems overwhelmed our server early
   in the initial send, causing it to reject all connections for 5 or 10
   minutes. When it recovered, only 3,600 copies of the 23,427 total had
   been sent, and Sendy, our email distribution software, wasn't
   automatically retrying as it's supposed to. You can imagine my
   distress.

   When our developer was able to take a look several hours later, he
   couldn't see any reason for the problem, so we created a duplicate
   campaign in Sendy, added a short parenthetical in the issue blurb
   apologizing for the resend to those who had already received it, and
   resent.

   Then I watched Sendy work through the sending process while keeping an
   eye on our server's load average (a measure of how busy it is; it had
   been sky-high when connections were being rejected earlier). Although
   the load average went uncomfortably high while sending (up to 11, when
   it should ideally stay below 2 on a 2-core server), Sendy chugged
   through until it had sent 23,427 issues. I assumed it was done and went
   to bed.

   Unfortunately, something else had gone wrong, and the server kept
   pushing out copies of the issue'shades of '[1]The Sorcerer's
   Apprentice''so some people received as many as 10. By the time I got up
   in the morning, it had stopped, and everything seemed back to normal,
   apart from all the reader messages alerting me to the problem. As much
   as I appreciate the effort, rest assured that someone else will
   undoubtedly have notified us. If you notice something weird like this
   in the future, check [2]TidBITS Talk to see if I've commented on it
   yet.

   Throughout the rest of the week, our smaller email
   distributions'articles sent to TidBITS members and the Japanese and
   Dutch translations'went out correctly, except for one Watchlist item
   that's still trying to send to the last 61 users after three days. I
   just restarted the server to see if that helps.

   I hope this issue sends properly, with everyone receiving just a single
   copy, but if not, you'll know the gremlin plaguing the server is still
   up to its mischief. Just delete any extras.

References

   1. https://en.wikipedia.org/wiki/The_Sorcerer%27s_Apprentice
   2. https://talk.tidbits.com/

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