The Perfect Woman

Yesterday my wife asked me to envision the perfect woman and then make a list of her virtues. She pleaded with me to have an open mind and not let it become a list of virtues she has or a list of virtues I wished she had. Here is what I came up with; order has no significance.

• Loving, capable of being a mother to anybody, but not pron to spoiling
• Faithful, spiritual, prayerful
• Graceful
• Intelligent in conversation, but not determined to win arguments
• Humorous, but not raucous
• Musical
• Humble, but not shy or awkward
• Confident, but not prideful
• Capable of leading, but never desiring to ^[1]
• Understanding of human emotions
• Socially proper
• Organized but no OCD
• Capable of cooking every day without the family tiring of her food ^[2]
• Frugal
• Long hair ^[3]

"A virtuous woman is a crown to her husband" - Proverbs 12:4

^[1] The wife in Legacy is the best example I can think of. She's able to take charge when she needs to.
^[2] This doesn't mean she has to cook every day, just that she could if needed to.
^[3] I added this after my wife pointed out that I didn't have any physical attributes in the list. I didn't think I needed any, but then I realized I always envision good women as having long hair.

My Mysterious Double Cron

One of the websites I manage at work has a cron associated with it that ran every Monday morning at 1:00 AM to process outstanding invoices.

0 1 * * 1 php cron_script.php >> cron_script.log 2>@1

The script worked beautifully until June 18 when everyone who was charged was billed twice. I first thought my script must have a bug, but further inspection proved that wasn't the case^[1].

The output log only had one entry for June 18, so I was inclined to blame it on network errors^[2].

But most signs showed that the cron had run twice, at almost the exact same time. I was reluctant to accept this because cron is a stable library, but the evidence was overwhelming. The order of the double-charge pairs was perfectly sequential.

11223344

If both executions weren't at almost the exact same moment you would see something more mixed.

12132434

We could see that from the responses we get back from our credit card processing company and store in the database, information stored in the eCommerce software to show customers when they were charged, and history that our credit card processing company keeps.

So the cron ran twice but logged its activity once. After much debate, the only plausible solution we could divine was that the NTP update script also ran at 1:00 AM and caused the clock to drift backwards a few hundred milliseconds and repeat 1:00 AM. We could explain the log file having on entry by assuming the first execution obtained an exclusive lock on the file.

But then I did some research and found out that NTP almost never drifts the clock backwards (especially not for such small intervals as we were expecting) and redirecting output in the shell to a file does not lock the file.

Our theory was sufficiently busted, and now we have no possible explanations for both anomalies:

• How did the cron run twice at the same time?
• Why did the output only get written to the log file once?

Surely it must have been cosmic rays.

^[1] Technically my script did have a bug in that it allowed people to be billed twice if the script ran twice at the same moment. That has since been fixed by applying an exclusive lock to the logfile. But I realize now that the fix is insufficient. I have a better idea.

^[2] We have had other problems related to network errors between us and our credit card processing company. My inclination to blame the network wasn't random.