并行循环中异常处理

msdn中针对并行循环中异常的处理给出了示例，如下。（个人觉得还不错）

在此示例中，将捕获所有异常，然后将它们包装在所引发的 System.AggregateException 中。调用方可以决定要处理哪些异常。

class ExceptionDemo2
{
    static void Main(string[] args)
    {
        // Create some random data to process in parallel.
        // There is a good probability this data will cause some exceptions to be thrown.
        byte[] data = new byte[5000];
        Random r = new Random();
        r.NextBytes(data);

        try
        {
            ProcessDataInParallel(data);
        }

        catch (AggregateException ae)
        {
            // This is where you can choose which exceptions to handle.
            foreach (var ex in ae.InnerExceptions)
            {
                if (ex is ArgumentException)
                    Console.WriteLine(ex.Message);
                else
                    throw ex;
            }
        }

        Console.WriteLine("Press any key to exit.");
        Console.ReadKey();
    }

    private static void ProcessDataInParallel(byte[] data)
    {
        // Use ConcurrentQueue to enable safe enqueueing from multiple threads.
        var exceptions = new ConcurrentQueue<Exception>();

        // Execute the complete loop and capture all exceptions.
        Parallel.ForEach(data, d =>
        {
            try
            {
                // Cause a few exceptions, but not too many.
                if (d < 0x3)
                    throw new ArgumentException(String.Format("value is {0:x}. Elements must be greater than 0x3.", d));
                else
                    Console.Write(d + " ");
            }
            // Store the exception and continue with the loop.                    
            catch (Exception e) { exceptions.Enqueue(e); }
        });

        // Throw the exceptions here after the loop completes.
        if (exceptions.Count > 0) throw new AggregateException(exceptions);
    }
}