Author Topic: Zip performance  (Read 5905 times)

veds

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Zip performance
« on: March 25, 2024, 19:29:42 »
When I want to add a few small files to an existing zip which contains a lot of small files (+200.000) a "copy to" dialog box appears but nothing seems to happen.
I waited 30 minutes and the copy process wasn't yet started.

MC v13.5 (x64) on windows 10

Mathias (Author)

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Re: Zip performance
« Reply #1 on: March 25, 2024, 20:48:19 »
Not able to recreate that.
But if the file you add already exist and you are overwriting (removing and adding), then it must rebuild the entire zip.
Also if the zip is missing its content catalogue at the end of the file (depending on what is created it from the beginning). the entire file need to be parsed instead of just jump to end and add it

However MC is not optimized to update zip is fastest way, normally it is not a problem but if you got 200.000+ items in the root of the zip i can cause it to be slow. Zip is handled like a virtual filesytem, you can navigate into the zip as a volume.
Because of this the zip archive must load the entire zip before doing anything to it. and for each file you add it must check so the file do not already exists. and so on.

However there are some optimization added in the coming version. (14.x) It will load a large zip faster.. but it will still be slow.. The way zip is build, having 200k+ items in a zip is not optimal. I think 7Zip handles large number of files better.
« Last Edit: March 26, 2024, 09:13:28 by Mathias (Author) »

veds

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Re: Zip performance
« Reply #2 on: March 26, 2024, 20:12:58 »
However there are some optimization added in the coming version. (14.x) It will load a large zip faster.
Thank you!

Also if the zip is missing its content catalogue at the end of the file
I created the archive with multicommander; I don't know whether multicommander adds a content catalogue at the end of the file.

I have send you an email with more info.

Mathias (Author)

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Re: Zip performance
« Reply #3 on: March 26, 2024, 20:55:28 »
If you browse into the zip.. It will scan the zip so it can show all files from the zip..
When you add files to an existing zip. the same things is happening. It needs first to scan the zip
So you can see how long time it takes to open the zip if you browse into it. it will take the same before it can start to add files into it