Java线程池写法改写为C#线程池写法

下面这段C#代码中的线程池部分还是Java的写法，请大神门帮忙改成C#写法。
示例代码，最终代码啥的都很欢迎！

 /// 

        /// 用户初始化ak和sk，sdk自己生成token 
        ///  
        ///  
        ///  
        ///  
        ///  
        ///  
        public virtual void execUpload(string bucketName, string fileKey, string randomFile, PutPolicy putPolicy, PutExtra putExtra, JSONObjectRet jsonObjectRet)
        {
            FileInfo randomFileInfo = null;
            ExecutorService pool = null;
            HttpClient mkfileHttpClient = null;
            int retry = 0;
            while (retry < 3)
            {
                string uploadBatch = "SDK-" + Guid.NewGuid();// UUID.randomUUID();
                retry++;
                try
                {
                    if (BaseBlockUtil.BLOCK_SIZE < 4 * BaseBlockUtil.MB || (BaseBlockUtil.BLOCK_SIZE % 4 * BaseBlockUtil.MB) != 0)
                    {
                        jsonObjectRet.onFailure(new Exception("块大小应该为4M的整数倍!"));
                        return;
                    }
                    randomFileInfo = new FileInfo(randomFile);
                    pool = Executors.newFixedThreadPool(BaseBlockUtil.THREAD_NUN);
                    CompletionService completionService = new ExecutorCompletionService(pool);
                    if (putExtra.processes == null || putExtra.totalSize != randomFileInfo.Length)
                    {
                        initPutExtra(bucketName, fileKey, randomFile, putExtra, jsonObjectRet);
                    }
                    putExtra.totalSize = randomFileInfo.Length;
                    putPolicy.deadline = Convert.ToString(DateUtil.ToJavaMilliseconds(DateUtil.nextNHours(1, DateTime.Now)));
                    DateTime dealEndDate = DateUtil.nextNMinutes(5, DateTime.Now);
                    string token = TokenUtil.getUploadToken(putPolicy);

                    int runnerThread = 0;
                    foreach (BlockObject blockObject in putExtra.processes)
                    {
                        runnerThread++;
                        while (runnerThread > (BaseBlockUtil.THREAD_NUN + 1))
                        {
                            completionService.take().get();
                            runnerThread--;
                        }
                        if (dealEndDate < DateTime.Now)
                        {
                            dealEndDate = DateUtil.nextNMinutes(5, DateTime.Now);
                            putPolicy.deadline = Convert.ToString(DateUtil.ToJavaMilliseconds(DateUtil.nextNHours(1, DateTime.Now)));
                            token = TokenUtil.getUploadToken(putPolicy);
                        }
                        //RandomAccessFile blockFile = new RandomAccessFile(randomFile, "r");
                        blockObject.setCommonParam(randomFile, bucketName, fileKey);
                        HttpClient httpClient = new HttpClient();
                        BlockUpload task = new BlockUpload(blockObject, jsonObjectRet, putExtra, token, httpClient, uploadBatch);
                        completionService.submit(task);
                    }

                    for (int i = 0; i < runnerThread; i++)
                    {
                        completionService.take().get();
                    }
                    pool.shutdown();

                    putPolicy.deadline = Convert.ToString(DateUtil.ToJavaMilliseconds(DateUtil.nextNHours(1, DateTime.Now)));
                    token = TokenUtil.getUploadToken(putPolicy);
                    mkfileHttpClient = WebRequestMethods.Http.HttpClient;
                    BaseBlockUtil util = new BaseBlockUtil(null, jsonObjectRet, putExtra, token, mkfileHttpClient);
                    SliceUploadHttpResult result = util.mkfile(token, fileKey, putExtra, 0, uploadBatch);


                    if (result.Status == 200)
                    {
                        string hash = WetagUtil.getEtagHash(randomFile);
                        if (result.Hash.Equals(hash))
                        {
                            jsonObjectRet.onSuccess(result.toJSON());
                            break;
                        }
                        else
                        {
                            Console.WriteLine(fileKey + " 文件hash与服务器不一致，文件重新上传");
                            putPolicy.overwrite = 1;
                            putExtra.processes = null;
                        }

                    }
                    else
                    {
                        if (result.Status == 412)
                        {
                            Console.WriteLine(fileKey + " 此文件块有缺失，文件重新上传");
                            putPolicy.overwrite = 1;
                            putExtra.processes = null;
                        }
                        else
                        {
                            jsonObjectRet.onFailure(new HttpClientException(result.Status, result.Response));
                            break;
                        }

                    }
                }
                catch (Exception e)
                {
                    jsonObjectRet.onFailure(e);
                }
                finally
                {
                    if (pool != null)
                    {
                        pool.shutdownNow();
                    }
                    if (mkfileHttpClient != null)
                    {
                        try
                        {
                            mkfileHttpClient.close();
                        }
                        catch (IOException)
                        {
                        }
                    }
                    if (randomFileInfo != null)
                    {
                        try
                        {
                            int reTime = 0;
                            while (!pool.Terminated && reTime < 50)
                            {
                                reTime++;
                                Thread.Sleep(1000);
                            }
                        }
                        catch (Exception)
                        {
                            Console.WriteLine("file close error");
                        }
                    }
                }
            }
        }