C# Datatable.Dispose() 会使其从内存中删除吗？

Datatable.Dispose() will make it remove from memory?

提问by Rajeev Kumar

I have researching through very simple code and get stuck on seeing the dispose() result of datatable

我已经研究了非常简单的代码，并被困在查看数据表的 dispose() 结果

Following is the code

以下是代码

DataTable dt= new Datatable();
SqlCommand Cmd = new SqlCommand("sp_getData",SqlCon);
SqlCommand.CommandType= CommandType.StroedProcedure;
SqlCon.Open();
sqlDataReader dr=  cmd.ExecuteReader();
dt.Load(dr);
SqlCon.Close();
grdView.DataSource =dt;
dt.Dispose() // Here I dispose the table as it is no use for me & wanna memory free from this

But after disposing off the datatable i still found that it is still showing RowCount = 10k.

但是在处理掉数据表后，我仍然发现它仍然显示 RowCount = 10k。

Does Dispose() method does not free up the memory & make object as null ??

Dispose() 方法不会释放内存并将对象设为 null 吗？

How can i make it as null or free up the memory occupied by this object ??

我怎样才能让它为空或释放这个对象占用的内存？

采纳答案by MoonKnight

DataSetand DataTabledon't actually have any unmanaged resources, so Dispose()doesn't actually do much. The Dispose()methods in DataSetand DataTableexists ONLY because of side effect of inheritance - in other words, it doesn't actually do anything useful in the finalization.

DataSet并且DataTable实际上没有任何非托管资源，因此Dispose()实际上并没有做太多事情。Dispose()inDataSet和 中的方法DataTable仅由于继承的副作用而存在 - 换句话说，它实际上在最终确定中没有做任何有用的事情。

It turns out that DataSets, DataViews, DataTablessuppress finalization in their constructorsc this is why calling Dispose()on them explicitly does nothing.

事实证明，DataSets, DataViews,DataTables在其构造函数中抑制终结，这就是为什么Dispose()显式调用它们什么都不做的原因。

Presumably, this happens because, as mentioned above, they don't have unmanaged resources; so despite the fact that MarshalByValueComponentmakes allowances for unmanaged resources, these particular implementations don't have the need and can therefore forgo finalization.

据推测，发生这种情况是因为，如上所述，他们没有非托管资源；因此，尽管MarshalByValueComponent允许非托管资源，但这些特定实现没有必要，因此可以放弃最终确定。

Overview of this Immense Answer:

这个巨大的答案的概述：

Without a doubt, Dispose should be called on any Finalizable objects.

DataTables are Finalizable.

Calling Dispose significantly speeds up the reclaiming of memory.

MarshalByValueComponentcalls GC.SuppressFinalize(this)in its Dispose()- skipping this means having to wait for dozens if not hundreds of Gen0collections before memory is reclaimed.

毫无疑问，应该在任何 Finalizable 对象上调用 Dispose。

数据表是可终结的。

调用 Dispose 显着加快了内存的回收。

MarshalByValueComponent调用GC.SuppressFinalize(this)它Dispose()- 跳过这意味着在Gen0回收内存之前必须等待数十个甚至数百个集合。

Further Reading:

进一步阅读：

See this questionand the related answer.

请参阅此问题和相关答案。

回答by Adam Houldsworth

Does Dispose() method does not free up the memory & make object as null ??

Dispose() 方法不会释放内存并将对象设为 null 吗？

Disposeand the disposal pattern is not for reclaiming managed memory or "deleting" managed objects (both things you cannot do and what the Garbage Collector is there for), it is for handling the disposal/release of unmanaged resources or other managed resources that have releasable items, such as SqlConnection. It certainlywon't nullthe reference, but may make it unusable from the time of disposal forwards.

Dispose并且处置模式不是用于回收托管内存或“删除”托管对象（您不能做的事情以及垃圾收集器的用途），它用于处理非托管资源或其他可释放托管资源的处置/释放项，例如SqlConnection。它当然不会null作为参考，但可能会使其从处置时起无法使用。

How can i make it as null or free up the memory occupied by this object ??

我怎样才能让它为空或释放这个对象占用的内存？

If you want to null the reference, simply dt = nullwill work, though this will notgive you any benefit as the DataTableinstance is referenced by grdView.DataSource. Both dtand grdView.DataSourcewill be references to the same underlying DataTableinstance.

如果您想将引用清空，则dt = null可以正常工作，尽管这不会给您带来任何好处，因为DataTable实例是由grdView.DataSource. 双方dt并grdView.DataSource会以同一个基础的参考DataTable实例。

I also suspect this is part of a method in which case dtis method-scoped anyway.

我也怀疑这是方法的一部分，在这种情况下无论如何dt都是方法范围的。

You shouldn't have to worry too much about any of this stuff. I'd be more concerned about having the SqlConnectionoutside of a try-finally/ using, you are at risk of leaving a connection open there.

你不必太担心这些东西。我会更关心/的SqlConnection外部，你有在那里打开连接的风险。try-finallyusing

I tend to favour calling Disposeon items that implement IDisposablefor what I think is a verygood reason: this is the public contract. The fact of whether calling it does anything or not is an implementation detailand is liable to changeat a moments notice.

我倾向于赞成呼吁Dispose在实现项目IDisposable什么，我认为这是一个非常好的理由：这是公共合同。调用它是否有任何作用的事实是一个实现细节，并且可能会随时更改。

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顺便说一句，我会完全重写您的代码：

var dt = new Datatable();

using (var conn = new SqlConnection(""))
using (var comm = new SqlCommand("sp_getData", conn))
{
    conn.Open();

    using (var reader = comm.ExecuteReader())
    {
        dt.Load(reader);
    }
}

grdView.DataSource = dt;

回答by Hasan Savran

Try to use Clear() function. It works great for me for disposing.

尝试使用 Clear() 函数。它对我来说非常适合处理。

DataTable dt = GetDataSchema();
//populate dt, do whatever...
dt.Clear();