System.OutofMemoryException throw while doing GZipStream Compression

Question

I am working in win forms. Getting errors while doing following operation. It shows me System.OutOfMemoryException error when i try to run the operation around 2-3 times continuously. Seems .NET is not able to free the resouces used in operation. The file i am using for operation is quite big, around more than 500 MB.

My sample code is as below. Please help me how to resolve the error.

try
{
   using (FileStream target = new FileStream(strCompressedFileName, FileMode.Create, FileAccess.Write))
   using (GZipStream alg = new GZipStream(target, CompressionMode.Compress))
   {
       byte[] data = File.ReadAllBytes(strFileToBeCompressed);
       alg.Write(data, 0, data.Length);
       alg.Flush();
       data = null;
    }
}
catch (Exception ex)
{
    MessageBox.Show(ex.ToString());
}

Answer 1

A very rough example could be

// destFile - FileStream for destinationFile 
// srcFile - FileStream of sourceFile
using (GZipStream gz = new GZipStream(destFile, CompressionMode.Compress))
{
     byte[] src = new byte[1024];
     int count = sourceFile.Read(src, 0, 1024);
     while (count != 0)
     {
         gz.Write(src, 0, count );
         count = sourceFile.Read(src, 0, 1024);
     }
}
// flush, close, dispose ..

So basically I changed your ReadAllBytes to read only chunks of 1024 bytes.

Answer 2

Replace ReadAllBytes with Stream.CopyTo

using (FileStream target = new FileStream(strCompressedFileName, FileMode.Create, FileAccess.Write))
using (GZipStream alg = new GZipStream(target, CompressionMode.Compress))
{
    using (var fileToRead = File.Open(.....))
    {
        fileToRead.CopyTo(alg);
    }
}

Answer 3

You can try to use this method to compress file MSDN link

    public static void Compress(FileInfo fileToCompress)
    {
        using (FileStream originalFileStream = fileToCompress.OpenRead())
        {
            using (FileStream compressedFileStream = File.Create(fileToCompress.FullName + ".gz"))
            {
               using (GZipStream compressionStream = new GZipStream(compressedFileStream, CompressionMode.Compress))
               {
                      originalFileStream.CopyTo(compressionStream);                                
               }
            }
        }
    }

usage:

string directoryPath = @"c:\users\public\reports";

DirectoryInfo directorySelected = new DirectoryInfo(directoryPath);

foreach (FileInfo fileToCompress in directorySelected.GetFiles())
{
    Compress(fileToCompress);
}