在使用块内，需要处理和重新启动 [英] Inside of using block, need to dispose and reinstantiate

问题描述

我正在尝试使用EF来提升将数千行写入数据库的性能。我发现SaveChanges（）的速度在一个上下文中随着时间的推移而降低，并且在n个插入之后处理和重新创建上下文可以帮助这个。

I am trying to enhance the performance of writing thousands of rows to a db using EF. I have found that the speed of SaveChanges() degrades over time within a single context, and disposing and recreating the context after n inserts can help this.

using(Context context = new Context())
{
    for(int i = 0; i < numberOfLines; i++)
    {
        context.Collection.AddObject(line);
        if (i % 100 == 0)
        {
            context.SaveChanges()
            // Here I would like to call dispose on context and then create a new one
        }
     }
}

当然，我需要使用或者做类似的事情，因为还有更多的事情，我需要确保在任何时间抛出异常时调用处理。

Of course, I need to use using or do something similar because there is a lot more going on and I need to ensure that dispose will be called if an exception gets thrown at any time.

任何想法？我知道我可以在一个try块之外声明这个上下文，然后最后用context.Dispose（）方法。我显然不想这样做。

Any ideas? I know I can declare the context outside of a try block, and then have a finally with context.Dispose(). I obviously don't want to do that though.

编辑：我意识到我发布的代码段并不完全显示为什么我试图这样做。 for循环在IF语句外的其他位置调用context.SaveChanges（）。所以当IF评估为真时，我已经多次调用SaveChanges（）。

I realized the code snippet I posted doesn't totally show why I am trying to do this. The for loop calls context.SaveChanges() in other spots outside of the IF statement. So when the IF evaluates to true, I've called SaveChanges() a number of times already.

推荐答案

这听起来像你基本上是想批量处理一个集合。这很简单，使用 MoreLINQ （也在NuGet ）：

It sounds like you basically want to process a collection in batches. That's simple using MoreLINQ (also on NuGet):

foreach (var batch in dataToUpload.Batch(100))
{
    using (var context = new Context())
    {
        foreach (var item in batch)
        {
            ...
        }
        context.SaveChanges();
    }
}

除了其他的东西， / em>你想要实现的目标（IMO）比使用一个循环支持 i％100 更清楚。

Aside from anything else, that describes what you're trying to achieve (IMO) much more clearly than using one loop with a check for i % 100 in it.

（ http://morelinq.googlecode.com 的原始链接不再有效，替换为当前的GitHub链接）

(Original link to http://morelinq.googlecode.com is no longer valid, replaced with current GitHub link)

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