Question

我无法理解为什么我今天收到System.IndexOutOfRangeException。我已经在程序工作8小时后收到它，并且异常发生的地方被执行了数百万次。这个地方很简单：

for (int i = 0; i < _goldDesiredOrdersBuy.Length; i++)
{
    _goldDesiredOrdersBuy[i] = -1;               // IndexOutOfRangeException! Strategy3.cs:line 666
}

我只在程序启动时初始化_goldDesiredOrdersBuy，所以保证在发生异常时初始化它：

private int[] _goldDesiredOrdersBuy = new int[MaxOrderbookDepth];

我还有另一个触摸此阵列的地方：

    private int GetGoldVolumeBuy(int bidQuotesPos)
    {
        if (_goldDesiredOrdersBuy[bidQuotesPos] > -1)
        {
            return _goldDesiredOrdersBuy[bidQuotesPos];
        }
        int result = GetGoldVolumeBuyNotCached(bidQuotesPos);
        _goldDesiredOrdersBuy[bidQuotesPos] = result;
        return result;
    }

就是这样。 _goldDesiredOrdersBuy在应用程序启动时初始化一次，保证初始化并且数组的长度不会在任何地方修改，所以我不明白我是如何收到IndexOutOfRangeException的，有什么想法吗？

Unhandled Exception: System.AggregateException: A Task's exception(s) were not observed either by Waiting on the Task or accessing its Exception property. As a result, the unobserved exception was rethrown by the finalizer thread. --->
   System.AggregateException: One or more errors occurred. --->
   System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at MyProj.Strategies.Strategy3.CalculateNewDesiredOrdersBuy() in C:\Oleg\projects\MyProj\MyProj\Strategies\Strategy3.cs:line 666
   at MyProj.Strategies.Strategy3.RecalculateBuyOrders() in C:\Oleg\projects\MyProj\MyProj\Strategies\Strategy3.cs:line 567
   at MyProj.Strategies.Strategy3.OnAllTablesUpdated() in C:\Oleg\projects\MyProj\MyProj\Strategies\Strategy3.cs:line 499
   at MyProj.Strategies.Strategy3.AllTablesUpdated() in C:\Oleg\projects\MyProj\MyProj\Strategies\Strategy3.cs:line 413
   at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.<ForWorker>b__c()
   at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask)
   at System.Threading.Tasks.Task.<>c__DisplayClass7.<ExecuteSelfReplicating>b__6(Object )
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.Wait()
   at System.Threading.Tasks.Parallel.ForWorker[TLocal](Int32 fromInclusive, Int32 toExclusive, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Func`4 bodyWithLocal, Func`1 localInit, Action`1 localFinally)
   at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally)
   at System.Threading.Tasks.Parallel.ForEach[TSource](IEnumerable`1 source, Action`1 body)
   at MyProj.Market.FinishUpdatingTables() in C:\Oleg\projects\MyProj\MyProj\Market.cs:line 449
   at Library.Exchange.Gate.DoGateIteration() in C:\Oleg\projects\MyProj\MyProj\Gate.cs:line 143
   at Library.Exchange.Gate.<Connect>b__0() in C:\Oleg\projects\MyProj\MyProj\Gate.cs:line 98
   at System.Threading.Tasks.Task.Execute()
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.TaskExceptionHolder.Finalize()

Answer 1

来自System.Array on MSDN

不保证所有实例成员都是线程安全的。

通过在多个线程之间共享此数组实例，您将违反文档。你应该正确锁定。

Answer 2

Imo 问题是你有几个函数接受像int index这样的参数（或类似的东西）并使用该参数从数组中恢复数据。

数组的大小没有改变，没关系。但即使您的数组长度是静态的并且等于（比如说）5，如果您尝试使用index>=5访问该数组，您将获得所描述的异常。

编辑

考虑到在for(...)循环中引发异常的另一种可能性，其中的边界用数组本身的大小标记，我会说考虑执行堆栈，你在 parallel中执行东西。所以，我假设此时数组的大小以某种方式发生变化。

要检查此项，您可以尝试执行以下操作：

int limit = _goldDesiredOrdersBuy.Length; //SET LIMIT BEFORE ITERATION
for (int i = 0; i < limit ; i++)
{
    _goldDesiredOrdersBuy[i] = -1;           
}

并检查错误是否仍然存在。

希望这有帮助。

Answer 3

好吧，这种方法不会检查传入的有效索引所以我会尝试在这里进行一些安全检查。

private int GetGoldVolumeBuy(int bidQuotesPos) 
{ 
    int result = -1;
    if(bidQuotesPos >= 0 && bidQuotesPos < _goldDesiredOrdersBuy.Length)
    {
        if (_goldDesiredOrdersBuy[bidQuotesPos] > -1) 
        { 
            return _goldDesiredOrdersBuy[bidQuotesPos]; 
        } 
        result = GetGoldVolumeBuyNotCached(bidQuotesPos); 
        _goldDesiredOrdersBuy[bidQuotesPos] = result; 
    }
    return result; 
}

我假设result=-1是一个有效的输出

Answer 4

您没有检查bidQuotesPos的值是否在数组的范围内。

private int GetGoldVolumeBuy(int bidQuotesPos) 
{ 
    if (bidQuotesPos < 0 || bidQuotesPos >= _goldDesiredOrdersBuy.Length)
    {
        // either throw an exception, or (less desireable) return a value so that the caller
        // knows that an error occurred.
        return HandleInvalidInputValue(bidQuotesPos);
    }

    if (_goldDesiredOrdersBuy[bidQuotesPos] > -1) 
    { 
        return _goldDesiredOrdersBuy[bidQuotesPos]; 
    } 
    int result = GetGoldVolumeBuyNotCached(bidQuotesPos); 
    _goldDesiredOrdersBuy[bidQuotesPos] = result; 
    return result; 
}

对于初始化一次且长度不变的集合的System.IndexOutOfRangeException如何？

4 个答案: