Resharper报“Possible multiple enumeration of IEnumerable”

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading;
 6 using System.Threading.Tasks;
 7 using ConsoleApplication2.EF;
 8 
 9 namespace ConsoleApplication2
10 {
11     class Program_IEnumerable
12     {
13         static void Main(string[] args)
14         {
15             // 异步访问数据库
16             Task.Run(() =>
17             {
18                 while (true)
19                 {
20                     reloadDb();
21                 }
22             });
23 
24             // 使用死循环不停的读取数据
25             int count = 1;
26             while (true)
27             {
28                 Console.WriteLine("第{0}读取", count);
29                 IEnumerable<string> names = getNames();
30 
31                 var allNames = new StringBuilder();
32                 foreach (var name in names)
33                     allNames.Append(name + ",");
34                 Thread.Sleep(500);
35 
36                 var allNames2 = new StringBuilder();
37                 foreach (var name in names)
38                     allNames2.Append(name + ",");
39                 if (allNames2 != allNames)
40                     Console.WriteLine("数据源发生了改变");
41                 count++;
42 
43                 Thread.Sleep(1000);
44             }
45 
46             Console.ReadKey();
47         }
48 
49         static void reloadDb()
50         {
51             using (var infosEntities = new TestEntities())
52             {
53                 infosEntities.Student.Add(new Student
54                 {
55                     EnrollmentDate = DateTime.Now,
56                     FirstMidName = "han",
57                     LastName = "zhu"
58                 });
59                 infosEntities.SaveChanges();
60             }
61             Thread.Sleep(1000);
62 
63             using (var infosEntities = new TestEntities())
64             {
65                 var entity = infosEntities.Student.FirstOrDefault(a => a.FirstMidName == "han");
66                 if (entity != null)
67                 {
68                     infosEntities.Student.Remove(entity);
69                     infosEntities.SaveChanges();
70                 }
71             }
72             Thread.Sleep(1000);
73         }
74 
75         static IEnumerable<string> getNames()
76         {
77             var infosEntities = new TestEntities();
78             return infosEntities.Student.Select(a => a.FirstMidName + " " + a.LastName);
79         }
80 
81     }
82 
83 }