eli5 Why does turning your device on and off often solve a technical issue?
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Imagine a whiteboard. The longer you use that whiteboard without erasing it, the more problems you’re likely to run into. It’ll become a struggle as you try and fit things into little gaps, and even if you could erase a few things here and there you’d still probably have to break up long things into multiple parts and accidentally erase or overwrite something important every now and again.
Computer memory is kind of like this. No software is perfect (including the operating system like Windows, MaxOS, Android, IOS, etc.) and the longer it runs the more clutter and small errors it generates in memory (IE: the metaphorical whiteboard). Restarting a device is the equivalent of completely erasing the whiteboard and starting from a clean slate.
Modern computers do a *lot*. Between the hardware components, operating system, and applications running on a computer, there are a ton of little conversations happening all the time. Each layer of the conversation has its own requirements, and not everything knows what everything else needs. This is by design, and frequently true whether we’re talking about a desktop computer or a thermostat.
When you turn your computer on, it has done a difficult-to-overstate amount of verification and work to faciliate your ability to sign in. Once you’re signed in, even more work happens because most people like to use computers for more than just space heaters. The really impressive part is that so much of this is effecitvely hidden from you, the user.
Imagine playing Jenga with a tower that had millions of pieces that move around constantly – some you care about, others you don’t. In this game, so many pieces have already moved by the time you put your hand on your first piece that it doesn’t even look like a tower anymore.
Computers have been Jenga towers for a ***LONG*** time, and they’ve gotten ***VERY*** good at recognizing when they’re about to be unstable, to the point that they can endure many pieces being out of place and everything will continue to run fine. They can be smart enough to not allow you to even think about pulling a particular piece, as it will certainly cause a [computer] crash.
Even while you’re playing your particular pieces, others are still moving without (and because of) your actions. Some peices (like device drivers) are so critical that they will insist on re-building the tower every time they get moved.
Eventually, moving pieces around gets difficult – they take longer to move, don’t slide in and out as easily as when you started, and may not even fit in areas they’re supposed to. That’s when you can either carry on until the tower falls (crash) or demand it rebuild itself (reboot), so that you can resume moving your desired pieces around easily and without frustration.
As programs run, they take in and produce data that is kept in the RAM. Sometimes that data can cause a program to run completely in circles or at least in directions that it’s not supposed to run. By shutting the computer down everything is halted, all the data in the RAM is erased and the program starts anew, with normal data.
It’s like shouting “Fuck this shit! We’re not getting anywhere. Let’s start from the beginning.” and then you start from the beginning and maybe this time things go right.
When you turn a device off it’s starting from a known State (off)
The longer a device runs the more of a chance of undefined behavior. Which causes issues.
To add to what others have said, turning it off and on is also a very easy and generally fast thing for the average user to do. A power user could potentially use the task manager or command prompt to fix some issues without needed a restart, but only very quick fixes would be worth the time.
Because your device runs programs. They’re intended to do particular things in particular orders. But writing perfect code is near-impossible, and there are always many, many things that can go wrong (because testing code is also hard, and labour-intensive, and finding every bug almost impossible). So there are always weird things that can go wrong.
Run the code long enough, and something will. And once it does, all bets are off – the program is in unknown territory, doing unknown things, and not doing what you want it to do any more. And it doesn’t known it’s lost, let alone how to get back out.
So you turn the device off and on, and all the programs start again at the beginning again, doing things they’re supposed to. Not lost anymore. Until next time.
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