使用transformblocks的糟糕表现

Question

我目前正在尝试使用TransformBlocks来让我的代码运行得更快。相反，我发现我基本上没有实现并行化：

正如您所看到的，存在相当多的死空间，I / O很少或其他问题阻止事物并行运行（注意：所有绿色块都是主线程）。

调用代码的基本结构如下：

var options = new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 8 };
var download = new TransformBlock<string, Tuple<string, string>>(s => sendAndReciveRequest(s), options);
var process = new TransformBlock<Tuple<string, string, TransformBlock<string, Tuple<string, string>>>, List<string>>(s => Helpers.ParseKBDL(s), options);
var toObjects = new TransformBlock<List<string>, List<Food>>(list => toFood(list), options);

for (char char1 = 'a'; char1 < 'z' + 1; char1++)
    download.Post(char1.ToString());

while ((download.InputCount != 0 || download.OutputCount != 0 || process.InputCount != 0) || (Form1.downloadCount != Form1.processCount))
{
    if (download.OutputCount == 0 && download.InputCount == 0)
    {
        continue;
    }
    var res = download.Receive();
    process.Post(new Tuple<string, string, TransformBlock<string, Tuple<string, string>>>(res.Item1, res.Item2, download));
}

注意：检查和元组混乱的原因是偶尔进程需要向下载块添加更多内容。我非常愿意改变这种组织方式。

所以我的问题：为什么这段代码没有达到加速？我怎样才能重组它以便我获得加速？