简单的生产者-消费者示例 C# 字典

Question

我迈出了并行编程的第一步。我写了一个最简单的代码，但结果很混乱。此代码采用生产者-消费者模式获取前 10 个最近的项目。只有 1 个消费者和 1 个生产者。有两个消费者时效果更好，但也不正确。

  public static void ProducerConsumer(string path)
    {
        var capacity = 50000;
        var collection = new BlockingCollection<string>(capacity);
        var dict = new Dictionary<string, int>();
        var tasks = new List<Task<Dictionary<string, int>>>();
        var producer = Task.Factory.StartNew(() =>
        {

            Parallel.ForEach(File.ReadLines(path), (line) =>
            {
                collection.Add(line);
            });
            collection.CompleteAdding();
        });

        for (int i = 0; i < 1; i++)
        {
            var consumer = Task.Factory.StartNew<Dictionary<string, int>>(() =>
            {
                var localDict = new Dictionary<string, int>();
                while (!collection.IsCompleted)
                {
                    string line;
                    if (collection.TryTake(out line))
                    {
                        Map(line, localDict);
                    }
                }
                return localDict;
            });
            tasks.Add(consumer);
        }
        int count = 0;
        while (tasks.Count > 0)
        {
            var id = Task.WaitAny(tasks.ToArray());

            var res = tasks[id].Result;
            count += res.Sum(k => k.Value);
            Aggregate(res, dict);
            tasks.RemoveAt(id);
        }
        Console.WriteLine($"Values sum : {count}");
        ShowResult(dict);
        ShowTotal(dict, "End");


    }
    public static void Map(string line, Dictionary<string, int> dict)
    {
        var parts = line.Split(new string[] { ";" }, StringSplitOptions.RemoveEmptyEntries);
        var streetName = parts[3];
        if (dict.Keys.Contains(streetName))
        {
            dict[streetName]++;
        }
        else
        {
            dict.Add(streetName, 1);
        }
    }
    public static void ShowResult(Dictionary<string, int> dict)
    {

        var res = dict.OrderByDescending(r => r.Value).Take(10).ToList();

        foreach (var key in res)
        {
            Console.WriteLine($"{key.Key} - {key.Value}");
        }
    }
    public static void Aggregate(Dictionary<string, int> part, Dictionary<string, int> main)
    {

        foreach (var key in part.Keys)
        {
            if (main.Keys.Contains(key))
            {
                main[key] += part[key];
            }
            else
            {
                main.Add(key, 1);
            }
        }
    }

    public static void ShowTotal(Dictionary<string, int> dict, string mark = null)
    {
        Console.WriteLine($"{mark ?? ""} Keys: {dict.Keys.Count} - Values:{dict.Sum(s => s.Value)}");
    }

调试时它显示了正确的步骤，但结果显示每个项目只有一个命中，总数不正确。

Answer 1

就像KooKiz说的，应该是

main.Add(key, part[key])

Answer 2

如果我理解你的算法，应该是：

main.Add(key, part[key])

简单的生产者-消费者示例 C# 字典

Simple producer-consumer example C# Dictionary

c#

dictionary

task

producer-consumer