Issue with trying to use GZipStream in C# to decompress a large gz file

Question

Issue with trying to use GZipStream in C# to decompress a large gz file

Zed Yang 0 Microsoft Employee

I'm trying to use GZipStream in C# to decompress a large gz file (compressed 2.5 GB -> decompressed 30 GB). Using the following code and the output file is always 50KB. I tried the same code on a much smaller gz file ~500MB and it worked fine. Wondering if there is any limitation to the GZipStream class. Below is my code, I got it from https://learn.microsoft.com/en-us/dotnet/api/system.io.compression.gzipstream?view=net-7.0

    private static void DecompressFile()
    {
        using (FileStream compressedFileStream = File.Open(gzipFilePath, FileMode.Open))         
		using (FileStream outputFileStream = File.Create(destinationFilePath))         
		using (var decompressor = new GZipStream(compressedFileStream, CompressionMode.Decompress))         		   	
		{             
			decompressor.CopyTo(outputFileStream);         
		}
    }

    
    ```

Answer 1

Jiachen Li-MSFT 21,711 Microsoft Vendor

Hi @Zed Yang ,

Please put decompressor. CopyTo(outputFileStream); in curly brackets after the Using statement to prevent the stream from being closed prematurely.

       private static void DecompressFile()
        {
            using (FileStream compressedFileStream = File.Open(CompressedFileName, FileMode.Open))
            using (FileStream outputFileStream = File.Create(DecompressedFileName))
            using (GZipStream decompressor = new GZipStream(compressedFileStream, CompressionMode.Decompress))
            {
                decompressor.CopyTo(outputFileStream);
            }
        }

Also try to use the TryCatch statement to catch possible exceptions.

Best Regards.

Jiachen Li

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Zed Yang 0 Microsoft Employee

@Jiachen Li-MSFT thanks for answering my question. however i tried the following 2 implementation and still no success. also the program ran fine without any exception.

            const int bufferSize = 1024 * 1024;  // 1 MB buffer size, but you can adjust this based on your needs.
            byte[] buffer = new byte[bufferSize];

            using (FileStream gzipStream = new FileStream(gzipFilePath, FileMode.Open))
            using (GZipStream decompressionStream = new GZipStream(gzipStream, CompressionMode.Decompress))
            using (FileStream targetStream = new FileStream(destinationFilePath, FileMode.Create))
            {
                int bytesRead;
                while ((bytesRead = decompressionStream.Read(buffer, 0, bufferSize)) > 0)
                {
                    targetStream.Write(buffer, 0, bytesRead);
                }
            }

                using (FileStream compressedFileStream = File.Open(gzipFilePath, FileMode.Open))
                using (FileStream outputFileStream = File.Create(destinationFilePath))
                using (var decompressor = new GZipStream(compressedFileStream, CompressionMode.Decompress))
                {
                    decompressor.CopyTo(outputFileStream);
                }

Jiachen Li-MSFT 21,711 Reputation points Microsoft Vendor

2023-11-14T06:29:01.9233333+00:00

My test environment can't test with such a large file.

What is the framework of your project?

Consider profile the code to monitor its behavior, especially memory consumption and CPU usage during the decompression process.

Issue with trying to use GZipStream in C# to decompress a large gz file

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