【工作中遇到的问题】Dictionary 在进行Add操作使报超出了数组界限的问题

问题代码的主要功能是用于记录页面的执行时间的:

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Web.Mvc;
 6 using TCWireless.Utility;
 7 using System.Threading;
 8 using TCBase.EagleEye.Metric;
 9
10 namespace TCWireless.Controller.BaseController
11 {
12     public class TimeFilter : ActionFilterAttribute
13     {
14         public string Name { get; set; }
15         //创建字典来记录开始时间，key是访问的线程Id.
16         private readonly Dictionary<int, DateTime> _start = new Dictionary<int, DateTime>();
17         public override void OnActionExecuting(ActionExecutingContext filterContext)
18         {
19             //过滤掉ChildAction， 因为ChildAction实际上不是一个单独的页面
20             if (filterContext.IsChildAction) return;
21             var currentThreadId = Thread.CurrentThread.ManagedThreadId;
22             try
23             {
24                 if (!_start.ContainsKey(currentThreadId))
25                 {
26                         _start.Add(currentThreadId, DateTime.Now);
27                 }
28             }
29             catch (Exception ex)
30             {
31                 LogWrapper.AddInfo("MobileHotel", "TimeFilter", "OnActionExecuting", ex);
32             }
33         }
34         public override void OnResultExecuted(ResultExecutedContext filterContext)
35         {
36             var currentThreadId = Thread.CurrentThread.ManagedThreadId;
37             if (!_start.ContainsKey(currentThreadId)) return;
38             try
39             {
40                 //计算出当前页面访问耗时
41                 var costSeconds = (DateTime.Now - _start[currentThreadId]).TotalMilliseconds;
42                 int value = Convert.ToInt32(costSeconds);
43                 MetricClient.Instance.LogTiming(Name, value);
44             }
45             catch (Exception ex)
46             {
47                 LogWrapper.AddInfo("MobileHotel", "TimeFilter", "OnResultExecuted", ex);
48             }
49             finally
50             {
51                     _start.Remove(currentThreadId);
52             }
53         }
54     }
55 }

问题出现在第26行.

然后百度发现其他人也有发现此类问题,原因是dictionnary是多线程不安全的.需要加上锁