Why do software installation or updates always go very fast up to 90% complete, then the last 5-10% takes so much longer?
In: Technology
For anything but the simplest package you’re not really installing “just” the software, you’re also installing helper libraries from other vendors.
Say your product depends on directx10, and some Visual Basic runtime, These things may well be already installed because many other products also use them, but your installer has to cope with them not being there critically your installer _doesnt know_ ahead of time if they are there.
As a user you see a progress bar that takes massive leaps because before it knew that directx was installed you were only 20% through, and now it turns out it is installed you are 80% of the way there, Visual Basic, also installed and youve jumped to 90% done, just the last 10% to do then. But the last 10% is your code, there is no way that’s already installed so that part always takes 10% of the worse case time.
Computer aphorism: The first 99% of the install takes 99% of the time. The last 1% takes the other 99%.
The core of the answer has been given above:
– inability to calculate how long it will really take on your Core 2 Duo
– best-guess implantation based on the creator’s own platform
But I’d also like to add that 99% of the time, the final part of the setup requires cleaning up files and verification of a complete install. That requires a bunch of io, opening/closing file handles, deleting numerous small files, etc.
Maybe a dowwnload then installation thing…?
Because the lazy programmer bases their percentages on number of files, prioritizing larger files first. The smaller files take longer due to indexing so it slows down.
Loading bars are super inconsistent. There are too many variables to accurately predict the speed unless artificially slowed.
When the software is written they try to do it but always get it incorrect. That is why it is usually super choppy
My guess for the quick last bit is it is closing up everything which doesn’t take long
Because software developers don’t think like normal people. To you, me and most end users the 100% progress bar means how much time do I need to waste before I can get on with my life.
To the programmer it’s a task list where each task may take 30 or 300 seconds. Nobody knows. It can take 5 minutes to get to 97% but the remaining 3% will take 15.
You invite people over to a party and you want to bring out the cake when everyone arrives. People keep asking you when’s cake. If you give a time estimate based on when you think people will fully arrive you will be way off. If you go by when the party starts you would be “stuck at 100%” for a while, or end up in over 100% time. So you just count who is there vs who all RSVP’d. 80% of the people show up before the party start but people trickle in.
A more concrete answer, progress bars can’t tell the future. In some cases you can go off of average run times if it’s on the same system. But usually for something like an installer, there’s multiple steps. Some will move for things like downloads, but you might have a step at the end that takes longer like compiling or coping files.
Basically it’s not a % of the amount of time left, but the amount of work, even if that work might go slower.
90%: purchasing and ordering new carpet, getting it delivered and actually laying it on the floor.
10%: Moving all the damn furniture, finding a place to put the fishtank, getting the sofa into the laundry, unwiring all the connections to the TV, router, computers etc, ungluing the patch in the hallway where it was cemented down, replacing the section of tack-track that broke….
Rarely are computer tasks able to be divided into uniform parts with each requiring the same amount of time to complete. Instead the overall task is composed of a host of unique functions, much like a zoo is composed of animals of varying sizes and types that need to be feed. Sure I know that the elephants take longer to feed hay than the birds need bird seed, but there are hundreds of birds and only a couple of elephants. And the cats need their food thawed and divided and carefully served to avoid being eaten. On top of that the monkey’s sometimes throw the food back or try to steal some more. So a zoo keeper knows most of these problems, but inevitably its the little stuff that are forgotten that takes 80% of the time. Nursing animals and sick animals, missing food, spoiled food, etc…. The Devil is in the details. So programmers can plan on the big stuff, but we typically underestimate the amount of time that all of the details take.
And every computer is like a different zoo, some with more monkeys and some with pre-thawed meat, …. So its hard to estimate.
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