我们可以使用Parallel.ForEach()将新元素添加到列表中吗? [英] Can we add new elements to a list using Parallel.ForEach()?

问题描述

我的代码做了很简单的事情

My code does very simple stuff

列表已包含元素.我在列表中大约有25000个元素(并且我希望有更多)，每个元素都很小(DateTime).

list already has elements. I have approximately 25000 elements (and I'm expecting to have more) in the list and each element is small (DateTime).

List<DateTime> newList = new List<DateTime>();
Parallel.ForEach(list, l => newlist.Add(new DateTime(l.Ticks + 5000)));

即，根据每个元素，我正在创建新元素并将其添加到其他列表中. 但是，这似乎不是一个好的编程方法.我 一些 遇到了这种例外，但并非每次都如此.

i.e, based on each element, I'm creating new elements and adding them to a different list. But, this doesn't seem to be a good programming approach. I hit this exceptions some times, but not everytime.

IndexOutOfRangeException : {"Index was outside the bounds of the array."}

我们可以使用Parallel.ForEach()将元素添加到列表中吗?如果是，为什么我会出现错误?如果没有，为什么?

Can we add elements to a list using Parallel.ForEach()? If yes, why do I hit the error? If no, why?

推荐答案

在这种情况下，您真正​​想要的是这样的东西:

What you would really want in this situation is more like this:

newlist = list.AsParallel().Select(l => new DateTime(l.Ticks + 5000)).ToList();

尽管您应该衡量性能，以查看这种情况是否还受益于并行化.

Although you should measure the performance to see if this situation even benefits from parallelization.

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