[HN Gopher] The code worked differently when the moon was full
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The code worked differently when the moon was full
Author : shanselman
Score : 130 points
Date : 2021-09-28 18:41 UTC (4 hours ago)
(HTM) web link (www.hanselman.com)
(TXT) w3m dump (www.hanselman.com)
| woliveirajr wrote:
| > Not strictly the cycle of the moon but close.
|
| Meh. Just the old 49.7 days cycle that it takes to overflow 32
| bits when measuring miliseconds.
|
| I was hoping for a "it works when I buy vanilla icecream and
| doesn't when I buy other flavour".
| swid wrote:
| I was also hoping the title was more accurate. In the lines of
| the famous story of not being able to send an email 500 miles.
|
| https://web.mit.edu/jemorris/humor/500-miles
| nashashmi wrote:
| I always thought the problem was obvious by the title. And
| felt good about myself for a long time after I read it. Now
| that I am well into adulthood knowing does not seem that
| amazing.
| pininja wrote:
| Thanks for sharing, this is a great read!
| Johnny555 wrote:
| The end of that article is a good reminder of the _units_
| command, I 've been using Google for units conversion for so
| long that I forgot about the standalone _units_. It even
| comes standard with OSX.
| acidburnNSA wrote:
| I love the GNU units program so much. I think I use it at
| least 4 times/week. It's useful for kitchen conversions and
| also quick nuclear fuel burnup calcs. For example I used it
| on this blog post covering the long-term sustainability of
| nuclear fuel resources on earth.
|
| https://whatisnuclear.com/blog/2020-10-28-nuclear-energy-
| is-...
| acdha wrote:
| I heard a great story a while back for a digitization project
| where historic content was being provided by many libraries
| around the world, including one in Russia.
|
| The quality of the scanned books was excellent, except for a
| weird distortion every so often where part of the page would be
| shifted partway through as if someone had shifted half the page
| in Photoshop. This was only noticed in books over a certain size
| so people were checking to see if there was some kind of
| mechanical problem with the scanner (these were robots with
| automatic page turners so it was plausible that there could be
| something which was only an issue past a certain position),
| trying to figure out of there was some way that the software had
| some kind of memory leak or other issue which would explain the
| long and inconsistent intervals.
|
| Eventually they were on a long-distance phone call to Moscow and
| not turning up anything when there was a loud rumble in the
| background. "What was that?" lead to the realization that the
| library's scan center was close to a subway tunnel. The vibration
| of a passing train was enough to cause a glitch but only if you
| happened to be scanning at the exact time it went by: the reason
| longer books were noticed was simply because having more pages
| meant that at any point in time a long book was more likely to be
| sitting in the scanner and the technicians running the scanner
| were apparently tuning out the trains as background noise. This
| was reportedly the first project they'd done with one of the scan
| robots which can process an entire book unattended so it was
| plausible that smaller past projects simply hadn't been scanning
| frequently enough to hit this problem or that some previous
| technician had simply noticed and immediately redone the scan.
| mhandley wrote:
| The phase of the moon really can affect performance. A friend of
| mine worked on wireless links in Scotland and was struggling with
| loss at certain times of day, but not exactly the same time every
| day. When they graphed loss against time, the pattern was really
| periodic over many days. The periodicity turned out to be 12
| hours 25 minutes, which they eventually realized is exactly the
| time between low tides. The problem was at low tide the reflected
| path off the water interfered with the line-of-sight path causing
| signal fading, whereas at high tide it interfered much less. In
| particular, see figure 2 of their paper for the correlation
| between tide height and SNR:
| https://homepages.inf.ed.ac.uk/mmarina/papers/EDI-INF-RR-136...
| As tide height really does depend on the phase of the moon,
| presumably their loss did too, if they measured for long enough.
| m4rtink wrote:
| I heard a story about an astronomer loosing the chance to be
| the first to report a commet one cold winter night - just as he
| wanted to send the email to report it, the Internet connection
| was dead! He ran from the observatory to the nearest place with
| Internet connectivity, but by the time he sent the email from
| there, there was already a report from another astronomer
| elsewhere, a few minutes ago.
|
| Reason for the mysterious network outage ? Thermal contraction!
| The observatory was connected to the Internet via an optical
| link to a highrise building in the city that contracted ever so
| slightly due to the very low temperature, moving the laser beam
| of the optical link out of alignment, shutting down the
| connection.
| [deleted]
| fragmede wrote:
| The moon is a nightime light source, and a pretty good one at
| that, every 30 days or so. Even after the invention of the
| light bulb it continues to light up the night. Thus it's _not_
| astrology to suggest that the phase of the Moon could affect
| things on Earth seeing as how it 's what causes tides. (It _is_
| astrology to suggest the Moon is causing an effect based on
| magic though).
| pedrocr wrote:
| Cool result. That figure 2 is begging for a scatter plot of SNR
| and tide level to see how well correlated they are.
| abkfenris wrote:
| I remember reading that paper when I was trying to figure out
| why we were having issues with a wireless link down in the
| Patagonia fjords.
|
| Unfortunately we didn't have the hardware or enough control
| over the link (it took negotiating access with armed forces to
| work on either end) to try to implement any of their ideas.
| ColinWright wrote:
| For those who are interested, this is why you usually have two
| dishes/aerials, vertically displaced, so that when one has
| destructive interference between the direct and reflected
| signals, the other has constructive interference. I learned
| something about this when writing data compression and
| encryption software for radar surveillance systems, where there
| were multiple radars over a moderate coverage area, all sending
| data via microwave links over water back to the Command and
| Control Centre.
| robocat wrote:
| In the analogue days, before pixels existed, a customer had
| trouble with their phone line not working when the moon was full.
|
| The problem was that they lived on the coast, and a subsurface
| junction box would get wet during king tides, causing the
| telephone line to fail.
| drdeadringer wrote:
| Reminds me of a story where a company's internet would regularly
| drop at the same time every day -- let's say 3pm.
|
| Nobody could figure it out so they called in an expert.
|
| After lots of attempts and figuring, one day the person in
| question happens to look out the window at the time in question
| ... and sees a service truck park exactly in line-of-sight
| between the business and their internet-signal pickup broadcast
| point.
|
| Ah ha!
| a-dub wrote:
| i once lived in an apartment in an old building where if you
| turned on the light in the bathroom the dsl would lose sync.
|
| why this would occur i'll never know. (probably old telephone
| wiring wrapped around old 110v wiring? maybe? or who knows what
| kind of weird leakage/ground loops may have existed)
| enobrev wrote:
| Quite a few years ago, I spent many hours making my way up
| the support tiers at Time Warner in Brooklyn to resolve some
| connection issues (cable modem). I patiently waded through
| each tier as they repeatedly asked me to reset my modem and
| my router and restart my computer and check every cable, etc.
| The same things I'd already done before (as an on-site tech
| myself, at the time) and as the previous support person asked
| me to repeat.
|
| Finally I made it to tier three, with someone who seemed
| obviously competent. Within about a minute, he checked the
| power usage on my modem and then historically, and knew
| immediately that if I moved my modem to another outlet, it
| would work.
|
| It did. Never had that type of connection issue again.
| Socketier wrote:
| This happened to me as well, only with DSL. The strip lights
| on the bathroom mirror (newly installed) would disconnect the
| internet when turned on.
|
| Such a weird thing to troubleshoot when you have a few people
| living in the same house.
| kalenx wrote:
| Now, this is a true phase-of-the-moon bug:
| http://ftp.informatik.rwth-aachen.de/jargon300/phaseofthemoo...
| veryfancy wrote:
| I hoped this would be an article about nethack.
| macintux wrote:
| > Bugs based on a time calculations can often show themselves
| later when view through a longer lens and scope of
| time...sometimes WAY longer than you'd expect.
|
| When I worked for BBN in '97-'98, someone from outside the
| company as I recall came to talk to a room of engineers about the
| wide variety of calendar-related behaviors in various UNIX
| systems that were expected to cause problems for Y2K.
|
| It was a very, very long list, often subtle issues, and I recall
| the concern in the room about the number of old systems in use by
| the DoD and others.
|
| Anyway, no real point to this other than date handling is one of
| the hardest things to get right in computing, ranking right
| behind _testing_ for the correct behavior.
| RegBarclay wrote:
| Dates are a pain.
|
| The date bug I committed with the longest tail was daylight
| time. It was all good until we got to a day with 25 hours when
| we "fell back."
| Jiro wrote:
| I had one of those on my Pebble:
|
| https://github.com/mattrossman/forecaswatch2/issues/44
| btilly wrote:
| I thought that this was going to be different story.
|
| There was a program I heard about back in the 90s which would
| literally crash depending on the phase of the moon!
|
| The story is that it wanted to print a date. The programmer
| happened to have an astronomy library available that gave a
| string containing the date. So the programmer called that, and
| then parsed out the date.
|
| Unfortunately the astronomy library wrote its result as a string
| to a point. The result included the phase of the Moon. The
| pointer was not declared to be long enough. And therefore, would
| crash if the name of the phase of the moon was too long!
| dllthomas wrote:
| http://catb.org/~esr/jargon/html/P/phase-of-the-moon.html
| huachimingo wrote:
| Funny enough, Nethack[1] had this implemented too (w:spoilers).
| See also wmoonclock[2](wmaker) for a nice "moon-clock".
|
| [1]https://nethackwiki.com/wiki/Time
|
| [2]https://www.dockapps.net/wmmoonclock
| NotaHera wrote:
| Elrond - 'There is moon programming here.. see?'
| tux3 wrote:
| Tangentially related, here's another fun bug that inexplicably
| cares what time it is: Open Office cannot print on Tuesdays
| (https://bugs.launchpad.net/ubuntu/+source/cupsys/+bug/255161...)
| invalidusernam3 wrote:
| A bit unrelated, but another fun one, "We can't send mail more
| than 500 miles": https://web.mit.edu/jemorris/humor/500-miles
| vidanay wrote:
| We once had a customer who would call us in a panic a couple of
| times a year saying our inspection equipment was experiencing
| unusually high false rejects and they were generating very high
| scrap rate. By the time we got a technician on site the next day,
| everything was working flawlessly and the customer couldn't
| reproduce the problem either. This went on for almost three years
| with various levels of escalation to the current management.
| Finally, one day a technician was on site for another project
| when the customer came up to him and said "It's happening right
| now! Come fix it!" The technician rushed over to the equipment
| and discovered that the sun was shining at exactly the right
| angle to cause a lens flare in one of our cameras. This happened
| twice a year as the sun moved along its trajectory. A
| strategically placed piece of opaque plastic fixed it
| permanently.
| imglorp wrote:
| Sometimes the day star lines up directly behind your satellite or
| microwave dish and you have very poor snr for a few minutes.
| unanswered wrote:
| Signed integers should be used as sparingly as floating-point.
| They should not be used in ordinary code because ordinary code
| has no use for them until they break something.
|
| The most notable exception would be languages which allow
| negative indexing, but IMHO if that were syntactic instead of
| relying on actual signed integers, it would be safer (I.e., [-
| $int] would be a different syntax from [(-$int)] and the latter
| would not be correctly typed.)
| AceJohnny2 wrote:
| As long as you don't traumatize the hard drives by yelling at
| them, feat. brendangregg & bcantrill:
|
| https://youtu.be/tDacjrSCeq4
| AceJohnny2 wrote:
| Tangentially, my last company made sophisticated routers,
| dissipating ~3kW of heat. We had hard drives in them for
| persistent logs.
|
| There was a big problem where we needed to upgrade the fans to
| deal with the heat dissipation, but it was _destroying_ the
| performance of the spinning disk HDDs due to the vibration of
| the fans.
|
| (these were 2U devices with 5 boards: 2 control-plane boards (1
| active, 1 on stand-by for redundancy) & 3 data-plane boards (2
| active, 1 stand-by))
| Dylan16807 wrote:
| So I'd say the obvious solution would be suspending the drive
| on relatively big pieces of rubber, like https://m.media-
| amazon.com/images/S/aplus-media/sc/a32b42cb-...
|
| If it was a big problem, that must not have been viable? Too
| cramped?
| AceJohnny2 wrote:
| Exactly, there was no room for the rubber dampeners that
| were the obvious solution, and much frustration from the
| engineers that this wasn't planned ahead.
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(page generated 2021-09-28 23:00 UTC)