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
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.
Maybe a dowwnload then installation thing…?
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.
Computer aphorism: The first 99% of the install takes 99% of the time. The last 1% takes the other 99%.
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.
Progress bars are totally arbitrary and up to whoever is writing the installer. Someone might do it based on % of files transferred, or % of total size transferred, something in between, or something completely unrelated.
That said, you (and I) probably notice the ones that are the least representative of actual behavior and forget about the ones that work as you’d expect, because brains are weird.
For a lot of software, it is in the main phase, unpacking the main data which can often be fewer but larger files, so its fairly steady. Near the end is where generally the smaller more plentiful files get unpacked and organized. The installer also has to clean up a lot of the working data from the install at this last point. Unpacking a large file takes less time per mb than unpacking a lot of smaller files because there is transfer time in between the files. Think of it like unfolding a table cloth with many folds verses a bunch of napkins one by one but with the same surface area.
You know how we can be on the way home and you’ve gotta go to the bathroom? You know you can hold it but the closer we get to the house the worse you have to pee? Kinda like that.
Think like you’re carrying a box with lots of toys in it. You need to take it from the living room to your room and place all them in the right spot.
Someone decided 90% of the work just carrying the box, 10% is putting them on place.
But carrying the box is quick, you can do it in a minute. Putting the toys in place takes a lot longer, maybe 4 minutes.
TL;DR Most software “loading” bars are fake. Meaning they don’t actually show the precise percent of the progress. It’s a guesstimate!
Source: Me! A manager in software testing with just over 10 years of experience
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