c# – 仅使用using语句的代码上的“Timeout expired”异常

Parallel.ForEach(allIds,new ParallelOptions { MaxDegreeOfParallelism = 8 },x => DoTheWork(x));

当线程数留给系统决定时：

Parallel.ForEach(allIds,x => DoTheWork(x));

运行一段时间后,我得到以下异常：

Timeout expired. The timeout period elapsed prior to obtaining a
connection from the pool. This may have occurred because all pooled
connections were in use and max pool size was reached.

我的应用程序中只有两种模式用于调用SQL：

第一：

using (var dc = new MyDataContext())
    {
        //do stuff
        dc.SafeSubmitChanges();
    }

第二：

using (var dc = new MyDataContext())
        {
            //do some other stuff
            DoStuff(dc);
        }

.....
    private void DoStuff(DataContext dc)
    {
       //do stuff
       dc.SafeSubmitChanges();
    }

我决定通过这种形式的逻辑来限制调用：

public static class DataContextExtention
{
    public const int SQL_WAIT_PERIOD = 5000;
    public static void SafeSubmitChanges(this DataContext dc)
    {
        try
        {
            dc.SubmitChanges();
        }
        catch (Exception e)
        {
            if (e.Message ==
                "Timeout expired.  The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached.")
            {
                System.Data.SqlClient.SqlConnection.ClearAllPools();
                System.Threading.Thread.Sleep(SQL_WAIT_PERIOD);
                dc.SafeSubmitChanges();
            }
            else
            {
                throw;
            }
        }
    }
}

这绝对没有区别.一旦应用程序抛出此类的第一个异常,应用程序中的各种随机位置(甚至与SQL服务器无关的代码行)都会开始抛出此异常.

问题1：是不是在宗教上使用声明应该防范这种情况？

Q2：出了什么问题,如何解决这个问题？

注意：大约有250,000个ID.我还在MaxDegreeOfParallelism = 16进行了测试,得到了相同的异常.