public static async Task ExtractToDirectoryAsync(this FileInfo file,DirectoryInfo folder)
    {

        ActionBlock<ZipArchiveEntry> block = new ActionBlock<ZipArchiveEntry>((entry) =>
        {
            var path = Path.Combine(folder.FullName,entry.FullName);

            Directory.CreateDirectory(Path.GetDirectoryName(path));
            entry.ExtractToFile(path);

        },new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 2 });

        using (var archive = ZipFile.OpenRead(file.FullName))
        {
            foreach (var entry in archive.Entries.Where(e => e.Name != string.Empty))
            {
                block.Post(entry);
            }
            block.Complete();
            await block.Completion;
        }

    }

并进行以下测试单元测试：

[TestMethod]
    public async Task ExtractTestAsync()
    {
        if (Resources.LocalExtractFolder.Exists)
            Resources.LocalExtractFolder.Delete(true);
        //  Resources.LocalExtractFolder.Create();
        await Resources.WebsiteZip.ExtractToDirectoryAsync(Resources.LocalExtractFolder);
    }

使用MaxDegreeOfParallelism = 1,事情工作,但2它不.

Test Name:  ExtractTestAsync
Test FullName:  Composite.Azure.Tests.ZipFileTests.ExtractTestAsync
Test Source:    c:\Development\C1\local\CompositeC1\Composite.Azure.Tests\ZipFileTests.cs : line 21
Test Outcome:   Failed
Test Duration:  0:00:02.4138753

Result Message: 
Test method Composite.Azure.Tests.ZipFileTests.ExtractTestAsync threw exception: 
System.IO.InvalidDataException: Unknown block type. Stream might be corrupted.
Result StackTrace:  
at System.IO.Compression.Inflater.Decode()
   at System.IO.Compression.Inflater.Inflate(Byte[] bytes,Int32 offset,Int32 length)
   at System.IO.Compression.DeflateStream.Read(Byte[] array,Int32 count)
   at System.IO.Stream.InternalCopyTo(Stream destination,Int32 bufferSize)
   at System.IO.Stream.CopyTo(Stream destination)
   at System.IO.Compression.ZipFileExtensions.ExtractToFile(ZipArchiveEntry source,String destinationFileName,Boolean overwrite)
   at System.IO.Compression.ZipFileExtensions.ExtractToFile(ZipArchiveEntry source,String destinationFileName)
   at Composite.Azure.Storage.Compression.ZipArchiveExtensions.<>c__DisplayClass6.<ExtractToDirectoryAsync>b__3(ZipArchiveEntry entry) in c:\Development\C1\local\CompositeC1\Composite.Azure.Storage\Compression\ZipArchiveExtensions.cs:line 37
   at System.Threading.Tasks.Dataflow.ActionBlock`1.ProcessMessage(Action`1 action,KeyValuePair`2 messageWithId)
   at System.Threading.Tasks.Dataflow.ActionBlock`1.<>c__DisplayClass5.<.ctor>b__0(KeyValuePair`2 messageWithId)
   at System.Threading.Tasks.Dataflow.Internal.TargetCore`1.ProcessMessagesLoopCore()
--- End of stack trace from prevIoUs location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Composite.Azure.Storage.Compression.ZipArchiveExtensions.<ExtractToDirectoryAsync>d__8.MoveNext() in c:\Development\C1\local\CompositeC1\Composite.Azure.Storage\Compression\ZipArchiveExtensions.cs:line 48
--- End of stack trace from prevIoUs location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Composite.Azure.Tests.ZipFileTests.<ExtractTestAsync>d__2.MoveNext() in c:\Development\C1\local\CompositeC1\Composite.Azure.Tests\ZipFileTests.cs:line 25
--- End of stack trace from prevIoUs location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

更新2

这是我自己去做并行,它不工作:)记住在continueWith中处理异常.

public static void ExtractToDirectorySemaphore(this FileInfo file,DirectoryInfo folder)
        {

            int MaxDegreeOfParallelism = 2;
            using (var archive = ZipFile.OpenRead(file.FullName))
            {

                var semaphore = new Semaphore(MaxDegreeOfParallelism,MaxDegreeOfParallelism);

                foreach (var entry in archive.Entries.Where(e => e.Name != string.Empty))
                {
                    semaphore.WaitOne();

                    var task = Task.Run(() =>
                    {
                        var path = Path.Combine(folder.FullName,entry.FullName);

                        Directory.CreateDirectory(Path.GetDirectoryName(path));
                        entry.ExtractToFile(path);
                    });
                    task.ContinueWith(handle =>
                    {
                        try
                        {
                            //do any cleanup/post processing
                        }
                        finally
                        {
                            // Release the semaphore so the next thing can be processed
                            semaphore.Release();
                        }
                    });
                }
                while(MaxDegreeOfParallelism-->0)
                    semaphore.WaitOne(); //Wait here until the last task completes.


            }

        }

这里是异步版本：

public static Task ExtractToDirectorySemaphoreAsync(this FileInfo file,DirectoryInfo folder)
        {
            return Task.Factory.StartNew(() =>
            {
                int MaxDegreeOfParallelism = 50;
                using (var archive = ZipFile.OpenRead(file.FullName))
                {

                    var semaphore = new Semaphore(MaxDegreeOfParallelism,MaxDegreeOfParallelism);

                    foreach (var entry in archive.Entries.Where(e => e.Name != string.Empty))
                    {
                        semaphore.WaitOne();

                        var task = Task.Run(() =>
                        {
                            var path = Path.Combine(folder.FullName,entry.FullName);

                            Directory.CreateDirectory(Path.GetDirectoryName(path));
                            entry.ExtractToFile(path);
                        });
                        task.ContinueWith(handle =>
                        {
                            try
                            {
                                //do any cleanup/post processing
                            }
                            finally
                            {
                                // Release the semaphore so the next thing can be processed
                                semaphore.Release();
                            }
                        },TaskContinuationOptions.AttachedToParent); // the outher task will wait for all.
                    }

                }
            });
        }

更新3

在handle.Exception中抛出以下异常.

{"Block length does not match with its complement."}  
[0] = {"A local file header is corrupt."}

必须找出ZipFile是否是线程安全的.