unzip very large number of files speed problem

Dec 9, 2009 at 3:35 PM

Used DotNetZip to zip a folder containing 98,000 files and 3,700 folders (1.7 GB).  Zipped in 30 minutes.  Unzipping using DotNetZip, however, takes about 4 hours.  This is the code:

Using zip As ZipFile = ZipFile.Read([path-and-name-of-zipfile)               
             
 [then either:]  zip.ExtractAll(txtDestFolder.Text, ExtractExistingFileAction.OverwriteSilently)
               
 [or:}           zip.ExtractAll(txtDestFolder.Text, ExtractExistingFileAction.DoNotOverwrite)
               
End Using

Is there a better method I could use to speed up the unzip process ?

thank you

Coordinator
Dec 11, 2009 at 7:16 PM

4 hours!  That's unacceptable.  Sounds like a performance bug in the unzip process.  I suspect it is setting file attributes more than once.

I'll have to look at it a little more closely and get back to you.  What version of DotNetZip are you using?

Coordinator
Dec 11, 2009 at 7:17 PM
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Dec 11, 2009 at 8:43 PM

Version is 1.8.4.28 dated Nov 11, 2009. Let me know if you’d like the zip file, have it available on FTP site.

Kate Carbery, Programmer / Analyst
PMC Software Inc.
Suite 11, 8 Bartles Corner Road
Flemington, NJ 08822
Voice: (908) 806-7824 Fax (908) 806-3951

Coordinator
Dec 11, 2009 at 8:54 PM

KC - how big is the zip?   Can you characterize the folder structure - how nested is it?  3700 toplevel folders?  Or.. are there multiple levels of subdirectory?  and how many files in each folder?

thanks.

Dec 11, 2009 at 9:40 PM

Archive is 265 mb. Folders go down 2-3 levels generally, 468 at top level, about half with 1 or 2 levels below that.

Kate Carbery, Programmer / Analyst
PMC Software Inc.
Suite 11, 8 Bartles Corner Road
Flemington, NJ 08822
Voice: (908) 806-7824 Fax (908) 806-3951
E-mail replies to: katec@pmcsoftware.com
Visit our website at: www.pmcsoftware.com

Dec 11, 2009 at 9:48 PM

Also, files distribution: is uneven, some folders might have 2 or 3 files, some dozens. The root has several hundred, otherwise the subfolders mostly would have a max of a few dozen.

Kate Carbery, Programmer / Analyst
PMC Software Inc.
Suite 11, 8 Bartles Corner Road
Flemington, NJ 08822
Voice: (908) 806-7824 Fax (908) 806-3951
E-mail replies to: katec@pmcsoftware.com
Visit our website at: www.pmcsoftware.com