7-zip extraction in C#

Question

I have a folder containing a million zip files which I need to extract. Two ways I have tried:

Way 1: Use the 7-zip exe file and System.Diagnostic Process as follows

 ProcessStartInfo p = new ProcessStartInfo();
 p.FileName = "7za.exe" 
 p.Arguments = "e " + sourceName; // sourceName is the name of the zip file
 p.WindowStyle = ProcessWindowStyle.Hidden;
 Process x = Process.Start(p);
 x.WaitForExit();

Way 2: Use the 7z.dll and SevenZipExtractor as follows

 SevenZipExtractor.SetLibraryPath(@"C:\Program Files\7-Zip\7z.dll");
 SevenZipExtractor zipFile = new SevenZipExtractor("inv1_0.zip");
 zipFile.ExtractArchive(@"c:\projects\extractor\extractor\bin\debug\inv1_0.dat");

Two things here:

a) Way 1 works perfectly fine. Way 2 doesn't work. Give the error "SevenZip.SevenZipArchiveException: Invalid archive: open/read error!". Can someone suggest why this could be happening when way 1 is giving the correct extracted file?

b) Since there are a million zip files, I am worried about using Way 1 : as in the Process. How expensive is to loop through a million zip files and use process for each one of them. I would really like to use Way 2 but for some reason it gives the exception.

Answer 1

You can't avoid the cost of unzipping 1,000,000 files, but you can choose the way it'll cost you - processor usage, or time. If you don't want to lock your main thread, let a secondary thread handle the file processing for you.

Options:

• If time isn't an issue, spawn a background thread with low priority.
• If you want to abuse your processors - spawn several threads, set processor affinity for each of them, let them do their work in parallel.

But that doesn't seem to be your issue at all. It seems to me that SevenZipExtractor is behaving in a different way than the standalone .exe. I would obviously stick to the first (working) option until I figured out what's wrong with the 2nd approach.

You may also want to pay a visit to sevenzipsharp's CodePlex discussion group.