并行Foreach竞争条件

Question

我有一个并行foreach在完成执行之前关闭连接的问题。当我有一个普通的foreach循环runnung它很慢，但它会返回一切。一旦我改变为并行foreach，它现在返回大约95％的数据并终止。

下面

是我使用的代码：

var USPostalCodes = repository.GetUSPostalCodes(); 
       var CAPostalCodes = repository.GetCAPostalCodes(); 

       Parallel.ForEach(spreadsheetinfo, location => 
       { 

        LocationData Locationdata = new LocationData() 
        { 
         id = location.Id, 
         Market = repository.GetMarketsForPostalCode(location.PostalCode, uploadedFile, USPostalCodes, CAPostalCodes), 
        }; 

        locationlist.Add(Locationdata); 
       }); 

I added the following code to check and see what was going on, and that fixed it so that it is returning all rows so i know that a race condition exists but what i can't figure out is why and how ot fix it. any suggestions would be greatly appreciated 

Console.WriteLine("Processing {0} on thread {1}", Locationdata, 
            Thread.CurrentThread.ManagedThreadId); 

Answer 1

locationlist可能不是线程安全的。 因此，你正在破坏列表。

相反，您应该使用.AsParrelel.Select()并行运行代表并返回IEnumerable<T>的结果。