我想写一个不那么智能的因子化程序，并试图用TPL来并行完成它。但是，在核2双核机上运行了大约15分钟后，我得到一个聚合异常，里面有一个溢出异常。堆栈跟踪中的所有条目都是.NET框架的一部分，溢出不是来自我的代码。如果能帮助我弄清楚为什么会发生这种情况，我将不胜感激。
下面是注释的代码，希望它足够简单易懂。
class Program
{
static List<Tuple<BigInteger, int>> factors = new List<Tuple<BigInteger, int>>();
static void Main(string[] args)
{
BigInteger theNumber = BigInteger.Parse(
"653872562986528347561038675107510176501827650178351386656875178" +
"568165317809518359617865178659815012571026531984659218451608845" +
"719856107834513527");
Stopwatch sw = new Stopwatch();
bool isComposite = false;
sw.Start();
do
{
/* Print out the number we are currently working on. */
Console.WriteLine(theNumber);
/* Find a factor, stop when at least one is found
(using the Any operator). */
isComposite = Range(theNumber)
.AsParallel()
.Any(x => CheckAndStoreFactor(theNumber, x));
/* Of the factors found, take the one with the lowest base. */
var factor = factors.OrderBy(x => x.Item1).First();
Console.WriteLine(factor);
/* Divide the number by the factor. */
theNumber = BigInteger.Divide(
theNumber,
BigInteger.Pow(factor.Item1, factor.Item2));
/* Clear the discovered factors cache, and keep looking. */
factors.Clear();
} while (isComposite);
sw.Stop();
Console.WriteLine(isComposite + " " + sw.Elapsed);
}
static IEnumerable<BigInteger> Range(BigInteger squareOfTarget)
{
BigInteger two = BigInteger.Parse("2");
BigInteger element = BigInteger.Parse("3");
while (element * element < squareOfTarget)
{
yield return element;
element = BigInteger.Add(element, two);
}
}
static bool CheckAndStoreFactor(BigInteger candidate, BigInteger factor)
{
BigInteger remainder, dividend = candidate;
int exponent = 0;
do
{
dividend = BigInteger.DivRem(dividend, factor, out remainder);
if (remainder.IsZero)
{
exponent++;
}
} while (remainder.IsZero);
if (exponent > 0)
{
lock (factors)
{
factors.Add(Tuple.Create(factor, exponent));
}
}
return exponent > 0;
}
}
这是被抛出的异常
Unhandled Exception: System.AggregateException: One or more errors occurred. ---
> System.OverflowException: Arithmetic operation resulted in an overflow.
at System.Linq.Parallel.PartitionedDataSource`1.ContiguousChunkLazyEnumerator.MoveNext(T& currentElement, Int32& currentKey)
at System.Linq.Parallel.AnyAllSearchOperator`1.AnyAllSearchOperatorEnumerator`1.MoveNext(Boolean& currentElement, Int32& currentKey)
at System.Linq.Parallel.StopAndGoSpoolingTask`2.SpoolingWork()
at System.Linq.Parallel.SpoolingTaskBase.Work()
at System.Linq.Parallel.QueryTask.BaseWork(Object unused)
at System.Linq.Parallel.QueryTask.<.cctor>b__0(Object o)
at System.Threading.Tasks.Task.InnerInvoke()
at System.Threading.Tasks.Task.Execute()
--- End of inner exception stack trace ---
at System.Linq.Parallel.QueryTaskGroupState.QueryEnd(Boolean userInitiatedDispose)
at System.Linq.Parallel.SpoolingTask.SpoolStopAndGo[TInputOutput,TIgnoreKey](QueryTaskGroupState groupState, PartitionedStream`2 partitions, SynchronousChannel`1[] channels, TaskScheduler taskScheduler)
at System.Linq.Parallel.DefaultMergeHelper`2.System.Linq.Parallel.IMergeHelper<TInputOutput>.Execute()
at System.Linq.Parallel.MergeExecutor`1.Execute[TKey](PartitionedStream`2 partitions, Boolean ignoreOutput, ParallelMergeOptions options, TaskScheduler taskScheduler, Boolean isOrdered, CancellationState cancellationState, Int32 queryId)
at System.Linq.Parallel.PartitionedStreamMerger`1.Receive[TKey](PartitionedStream`2 partitionedStream)
at System.Linq.Parallel.AnyAllSearchOperator`1.WrapPartitionedStream[TKey](PartitionedStream`2 inputStream, IPartitionedStreamRecipient`1 recipient, BooleanpreferStriping, QuerySettings settings)
at System.Linq.Parallel.UnaryQueryOperator`2.UnaryQueryOperatorResults.ChildResultsRecipient.Receive[TKey](PartitionedStream`2 inputStream)
at System.Linq.Parallel.ScanQueryOperator`1.ScanEnumerableQueryOperatorResults.GivePartitionedStream(IPartitionedStreamRecipient`1 recipient)
at System.Linq.Parallel.UnaryQueryOperator`2.UnaryQueryOperatorResults.GivePartitionedStream(IPartitionedStreamRecipient`1 recipient)
at System.Linq.Parallel.QueryOperator`1.GetOpenedEnumerator(Nullable`1 mergeOptions, Boolean suppressOrder, Boolean forEffect, QuerySettings querySettings)
at System.Linq.Parallel.QueryOpeningEnumerator`1.OpenQuery()
at System.Linq.Parallel.QueryOpeningEnumerator`1.MoveNext()
at System.Linq.Parallel.AnyAllSearchOperator`1.Aggregate()
at System.Linq.ParallelEnumerable.Any[TSource](ParallelQuery`1 source, Func`2 predicate)
at PFact.Program.Main(String[] args) in d:\myprojects\PFact\PFact\Program.cs:line 34
如果能得到帮助，我将感激不尽
谢谢你的帮助
EDIT
按照Simon的回答，我再次运行了这段代码，这次是以 catch(AggregateException x) 句，我检查了该句中的所有内容。InnerExceptions 的集合。刚好有2个元素（我假设是每个执行线程一个，因为我有2个CPU核，TPL会优化到只用2个线程）。两个异常都是一样的（都是 OverflowException)... 所以这不是答案。
解决办法
Henk的答案原来是正确的，以下是来自microsoft博客的半官方链接，证实了这一点。PLINQ的Beta2版有什么新内容？
通过你的堆栈跟踪，在顶部附近，我看到了这个。
at System.Linq.Parallel.PartitionedDataSource`1.
ContiguousChunkLazyEnumerator.MoveNext(T& currentElement, Int32& currentKey)
at System.Linq.Parallel.AnyAllSearchOperator`1.
AnyAllSearchOperatorEnumerator`1.MoveNext(Boolean& currentElement, Int32& currentKey)
这看起来像是TPL枚举器在使用Int32进行内部记账 你可能做了比Int32.MaxValue更多的迭代... ...
要确定的话，你必须看一下迭代块生成的statemachine的IL。
这主要是一个猜测，因为还没有运行你的代码15分钟来测试它=;-)但鉴于你得到一个溢出异常，会不会是你的 exponent 增长大于 2,147,483,647.
int exponent = 0;
也许可以做到这一点。
BigInteger exponent = 0;
我希望能看到 CheckAndStoreFactor 方法，但内部异常之一的堆栈跟踪。(记住 AggregateException 拥有 InnerExceptions 属性，该属性可能包含多个内部异常）。)