The fastest GZIP decompress library in .NET [closed]

Answer 1

I found problems with Microsoft's GZipStream implementation not being able to read certain gzip files, so I have been testing a few libraries.

This is a basic test I adapted for you to run, tweak, and decide:

using System;
using System.Diagnostics;
using System.IO;
using System.IO.Compression;
using NUnit.Framework;
using Ionic.Zlib;
using ICSharpCode.SharpZipLib.GZip;

namespace ZipTests
{
    [TestFixture]
    public class ZipTests
    {
        MemoryStream input, compressed, decompressed;
        Stream compressor;
        int inputSize;
        Stopwatch timer;

        public ZipTests()
        {
            string testFile = "TestFile.pdf";
            using(var file = File.OpenRead(testFile))
            {
                inputSize = (int)file.Length;
                Console.WriteLine("Reading " + inputSize + " from " + testFile);
                var ms = new MemoryStream(inputSize);
                file.Read(ms.GetBuffer(), 0, inputSize);
                ms.Position = 0;
                input = ms;
            }
            compressed = new MemoryStream();
        }

        void StartCompression()
        {
            Console.WriteLine("Using " + compressor.GetType() + ":");
            GC.Collect(2, GCCollectionMode.Forced); // Start fresh
            timer = Stopwatch.StartNew();
        }

        public void EndCompression()
        {
            timer.Stop();
            Console.WriteLine("  took " + timer.Elapsed
                + " to compress " + inputSize.ToString("#,0") + " bytes into "
                + compressed.Length.ToString("#,0"));
            decompressed = new MemoryStream(inputSize);
            compressed.Position = 0; // Rewind!
            timer.Restart();
        }

        public void AfterDecompression()
        {
            timer.Stop();
            Console.WriteLine("  then " + timer.Elapsed + " to decompress.");
            Assert.AreEqual(inputSize, decompressed.Length);
            Assert.AreEqual(input.GetBuffer(), decompressed.GetBuffer());
            input.Dispose();
            compressed.Dispose();
            decompressed.Dispose();
        }

        [Test]
        public void TestGZipStream()
        {
            compressor = new System.IO.Compression.GZipStream(compressed, System.IO.Compression.CompressionMode.Compress, true);
            StartCompression();
            compressor.Write(input.GetBuffer(), 0, inputSize);
            compressor.Close();

            EndCompression();

            var decompressor = new System.IO.Compression.GZipStream(compressed, System.IO.Compression.CompressionMode.Decompress, true);
            decompressor.CopyTo(decompressed);

            AfterDecompression();
        }

        [Test]
        public void TestDotNetZip()
        {
            compressor = new Ionic.Zlib.GZipStream(compressed, Ionic.Zlib.CompressionMode.Compress, true);
            StartCompression();
            compressor.Write(input.GetBuffer(), 0, inputSize);
            compressor.Close();

            EndCompression();

            var decompressor = new Ionic.Zlib.GZipStream(compressed,
                                    Ionic.Zlib.CompressionMode.Decompress, true);
            decompressor.CopyTo(decompressed);

            AfterDecompression();
        }

        [Test]
        public void TestSharpZlib()
        {
            compressor = new ICSharpCode.SharpZipLib.GZip.GZipOutputStream(compressed)
            { IsStreamOwner = false };
            StartCompression();
            compressor.Write(input.GetBuffer(), 0, inputSize);
            compressor.Close();

            EndCompression();

            var decompressor = new ICSharpCode.SharpZipLib.GZip.GZipInputStream(compressed);
            decompressor.CopyTo(decompressed);

            AfterDecompression();
        }

        static void Main()
        {
            Console.WriteLine("Running CLR version " + Environment.Version +
                " on " + Environment.OSVersion);
            Assert.AreEqual(1,1); // Preload NUnit
            new ZipTests().TestGZipStream();
            new ZipTests().TestDotNetZip();
            new ZipTests().TestSharpZlib();
        }
    }
}

And the result in the system I am currently running (Mono on Linux), is as follows:

Running Mono CLR version 4.0.30319.1 on Unix 3.2.0.29
Reading 37711561 from /home/agustin/Incoming/ZipTests/TestFile.pdf
Using System.IO.Compression.GZipStream:
  took 00:00:03.3058572 to compress 37,711,561 bytes into 33,438,894
  then 00:00:00.5331546 to decompress.
Reading 37711561 from /home/agustin/Incoming/ZipTests/TestFile.pdf
Using Ionic.Zlib.GZipStream:
  took 00:00:08.9531478 to compress 37,711,561 bytes into 33,437,891
  then 00:00:01.8047543 to decompress.
Reading 37711561 from /home/agustin/Incoming/ZipTests/TestFile.pdf
Using ICSharpCode.SharpZipLib.GZip.GZipOutputStream:
  took 00:00:07.4982231 to compress 37,711,561 bytes into 33,431,962
  then 00:00:02.4157496 to decompress.

Be warned that this is Mono's GZIP, and Microsoft's version will give its own results (and as I mentioned, just can't handle any gzip you give it)

This is what I got on a windows system:

Running CLR version 4.0.30319.1 on Microsoft Windows NT 5.1.2600 Service Pack 3
Reading 37711561 from TestFile.pdf
Using System.IO.Compression.GZipStream:
  took 00:00:03.3557061 to compress 37.711.561 bytes into 36.228.969
  then 00:00:00.7079438 to decompress.
Reading 37711561 from TestFile.pdf
Using Ionic.Zlib.GZipStream:
  took 00:00:23.4180958 to compress 37.711.561 bytes into 33.437.891
  then 00:00:03.5955664 to decompress.
Reading 37711561 from TestFile.pdf
Using ICSharpCode.SharpZipLib.GZip.GZipOutputStream:
  took 00:00:09.9157130 to compress 37.711.561 bytes into 33.431.962
  then 00:00:03.0983499 to decompress.

It is easy enough to add more tests...

Answer 2

I've have had good performance with SevenZipLib for very large files, but I was using the native 7zip format and highly compressible content. If you're using content that won't have a high compression ratio, then your throughput will vary greatly compared to some of the benchmarks you can find for these libraries.

Answer 3

Compression performance benchmarks vary based on the size of streams being compressed and the precise content. If this is a particularly important performance bottleneck for you then it'd be worth your time to write a sample app using each library and running tests with your real files.