ConcurrentBag< T>和lock（List< T>）添加或删除哪个更快？

问题描述

我需要在 List< T> 上执行一些线程安全操作。通常我只是简单地使用：

I need to perform some thread safe operations on List<T>. Usually I just simply use:

lock(List<T>)
{
   List<T>.Add();
   List<T>.Remove();
}

我知道还有另一种方法，使用 ConcurrentBag< T> 。但是我不知道哪个更快，或者有其他区别。

I know there is another way, using ConcurrentBag<T>. But I don't know which is faster, or any other differences.

编辑：

有人建议我使用 ConcurrentBag ，因为这样做更安全。但是我担心这会使我的操作变慢。

Some people just recommend I use ConcurrentBag, because that's safer. But I worry it will make my operation slower.

我有很多线程需要从 List< T> ，我想知道哪种方法对性能更好。

I have a lot of threads needing to add or remove objects from a List<T>, I want to know which way is better for performance.

推荐答案

您可以轻松衡量尝试一下就可以采用不同的方法！那就是我刚刚得到的：

You can easily measure the performance of different approaches just by trying them out! That is what I just got:

lock list: 2.162s
ConcurrentBag: 7.264s

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;

public class Test
{
    public const int NumOfTasks = 4;
    public const int Cycles = 1000 * 1000 * 4;

    public static void Main()
    {
        var list = new List<int>();
        var bag = new ConcurrentBag<int>();

        Profile("lock list", () => { lock (list) list.Add(1); });
        Profile("ConcurrentBag", () => bag.Add(1));
    }

    public static void Profile(string label, Action work)
    {
        var s = new Stopwatch();
        s.Start();

        List<Task> tasks = new List<Task>();

        for (int i = 0; i < NumOfTasks; ++i)
        {
            tasks.Add(Task.Factory.StartNew(() =>
            {
                for (int j = 0; j < Cycles; ++j)
                {
                    work();
                }
            }));
        }

        Task.WaitAll(tasks.ToArray());

        Console.WriteLine(string.Format("{0}: {1:F3}s", label, s.Elapsed.TotalSeconds));
    }
}

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