General Question

Rarebear's avatar

Computer question. Why would something not work and then work?

Asked by Rarebear (21075 points ) January 4th, 2014

I have a software program on Windows 7 64 bit that I haven’t used in about 2 years. It’s a specific program for video capturing off a webcam (I was trying to image Jupiter last night). I was able to acquire an image, adjust the shutter speed and gain, etc., but when I tried to record it, I got an error message that said that the codec was wrong (It wasn’t. My camera uses the Y800 codec).

I did what any normal human would do and try it about 6 times, and I got the same error message. I even tried different codecs.

Finally, I gave up and went to a different program. That worked for awhile, but then crashed, so before packing up my equipment, just on a lark, I went back to the first program and all of a sudden it started working. I didn’t change anything.

Was the program upset that I hadn’t used it in 2 years or something and then stopped sulking?

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20 Answers

gorillapaws's avatar

“I didn’t change anything”

Well you quit the app and then launched it again later. This procedure causes memory to be deallocated and then reallocated. Some bugs are non-deterministic and there can literally be millions of different possible sequences of execution if there is asynchronous code. All code paths cannot be tested in such cases.

tom_g's avatar

First rule of tech support is to reboot and try again.

Anyway, @gorillapaws got it.

CWOTUS's avatar

It may also be a feature of the program that it checks the Web for updates and self-updates. This can happen in the background sometimes, but it more often requires that the program be shut down and restarted so the new drivers, etc. can be loaded into memory. Your original starting of the program may have had it operating in the 2-year-old-version mode, where it still worked fine by your lights. As you were running, it may have been self-updating and installing some drivers (those that it could while the program was operating), but then discovered a conflict between old and new, which manifested as an error. Your shutting down the program could then have allowed the full update to take effect, allowing the program to run flawlessly upon the restart.

Reboot and retry, yeah.

Rarebear's avatar

Thanks, that’s what I did initially, and it didn’t work. But obviously something in the background changed. I just hate not knowing…

ccrow's avatar

Personally, I think it probably was sulking.

Response moderated (Unhelpful)
jerv's avatar

I think @gorillapaws nailed it. Memory issues are odd beasts, and I had similar things happen all the time when I found out a DIMM went bad. It can also happen when other programs, especially those with memory leaks, misbehave. It’s common enough that The New Hackers Dictionary actually has a name for it: Heisenbug.

dabbler's avatar

@jerv Good point, a bad DIMM or badly seated DIMM will do some very weird things.
And thanks for the new word, Heisenbug! Makes total sense.

gorillapaws's avatar

@jerv There’s also the mandlebug.

Rarebear's avatar

I’m thinking you guys are correct in that it’s a memory issue. Who knows what background programs were running at the time chewing up RAM

mattbrowne's avatar

The dependencies are just too great. It’s almost impossible to recreate previous conditions.

Very unlikely, though not impossible is this

http://en.wikipedia.org/wiki/RAM_parity

with two changed bits.

jerv's avatar

I generally keep a Linux boot CD around just for memory tests. If nothing else, cutting Windows out of the mix will tell you whether it’s a hardware issue or just applications behaving badly.

Rarebear's avatar

@jerv I’m not smart enough to use Linux.

jerv's avatar

@Rarebear In that case, you really shouldn’t be using Windows… or eating utensils.

Sure, back in the old days, you needed to use console commands to do just about anything, but these days, if you know what language you speak and what time zone you are in, you can install Linux in a couple of clicks. If you can operate Windows at even the basic level of knowing how to open a browser and shut the computer down when you are done, you can use Linux. If you can’t, then how did you get onto Fluther?

However, for MEMTEST, you really don’t need even that basic level of competence.. When you boot from the CD, a menu comes up. The usual options include “Boot from Live CD”, which usually happens by default if you do nothing for a few seconds, and “Test Memory”.

If you can put a CD in the tray (or a USB Flash drive in the USB port) and select menu items using the up/down arrow and ENTER, you can run a memory test.

Rarebear's avatar

@jerv all my astrophotography programs require Windows. Linux is not an option for me.

jerv's avatar

@Rarebear WINE runs Windows applications under any POSIX-compliant OS, including Linux, so the only reason it’s not an option is that you don’t want it to be. I’m not saying to switch, merely setting the facts straight.

Then again, the boot CD/USB stick for a memory test is merely a tool that makes no permanent alterations to your system at all. Does taking your temperature permanently alter your mouth? As soon as you reboot after the test or after a live Linux session, it’s as if it never existed.

Rarebear's avatar

WINE has reported problems with several astrophotography programs. And why would I use WINE if I have windows?

jerv's avatar

@Rarebear It’s moot since the Linux boot device won’t alter anything on your system. It’s merely a diagnostic tool. Remove the disc/USB stick, reboot, and you’re back in Windows. I’m just telling you how to test your system to make sure it’s not a hardware issue, yet you’d think I asked you to engage in human sacrifice. Now I’m trying to understand your deep phobia of Linux. That’s the beauty of live CDs/sticks; no skill required, and no permanent changes to your system. You’ll still have everything just the way it is. Linux won’t give you AIDS.

Rarebear's avatar

@jerv. I don’t have a deep phobia of Linux. I just haven’t had a need for it.

Thank you for your help.

jerv's avatar

Well, I generally run Win7 myself, but live boot for hardware diagnostics is handy for those of us that do a bunch of PC repair. Most of those tools use Linux because it’s small and can run on the most meager of systems. Then again, I also work on my own cars, so I suppose I have a lot of tools that most people have no use for.

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