.NET：如何并行的从集合中返还元素？

实现代码

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Threading;
 7 using System.Collections.Concurrent;
 8 
 9 namespace CSharpStudy.ParallelStudy
10 {
11     class HowToReturnList
12     {
13         public static void Error_Test()
14         {
15             var list = Enumerable.Range(1, 1000);
16 
17             var results = new List<string>();
18             Parallel.ForEach(list, (item) =>
19             {
20                 results.Add("item:" + item);
21             });
22 
23             Console.WriteLine(results.Count);
24         }
25 
26         public static void Lock_Test()
27         {
28             var list = Enumerable.Range(1, 1000);
29 
30             var results = new List<string>();
31             Parallel.ForEach(list, (item) =>
32             {
33                 lock (results)
34                 {
35                     results.Add("item:" + item);
36                 }
37             });
38 
39             Console.WriteLine(results.Count);
40         }
41 
42         public static void Concurrent_Collections_Test()
43         {
44             var list = Enumerable.Range(1, 1000);
45 
46             var results = new ConcurrentQueue<string>();
47             Parallel.ForEach(list, (item) =>
48             {
49                 lock (results)
50                 {
51                     results.Enqueue("item:" + item);
52                 }
53             });
54 
55             Console.WriteLine(results.Count);
56         }
57 
58         public static void Task_Test()
59         {
60             var list = Enumerable.Range(1, 1000);
61 
62             var tasks = list.Select(item =>
63             {
64                 return Task.Run<string>(() =>
65                 {
66                     return "item:" + item;
67                 });
68             }).ToArray();
69             Task.WhenAll(tasks);
70 
71             Console.WriteLine(tasks.Select(x => x.Result).Count());
72         }
73 
74         public static void PLinq_Test()
75         {
76             var list = Enumerable.Range(1, 1000);
77 
78             var results = list.AsParallel().Select(item => "item:" + item);
79 
80             Console.WriteLine(results.Count());
81         }
82     }
83 }