IDataReader 造成的 .NET 对象水合作用导致性能下降

发布于 2024-07-16 05:38:01 字数 1649 浏览 3 评论 0原文

我正在尝试水合约 400 个业务对象的列表，当需要水合字符串时，性能变得非常慢。 400 个物体的水合需要超过 20 秒。

编辑

我们使用 MySQL 5.1 和 dotConnect for MySQL v5.0.12 作为数据提供者http://www.devart.com/dotconnect/mysql/

我做了一些基准测试，将其范围缩小到导致问题的字符串类型。我开始测量从记录 2 到记录 n 的时间，以忽略加载其他程序集可能占用的时间。

下面的代码在 0 毫秒内水合 1 个对象

objUserInfo.PortalID = portalId
objUserInfo.IsSuperUser = Convert.ToBoolean(dr("IsSuperUser"))
objUserInfo.UserID = Convert.ToInt32(dr("UserID"))

这也在 0 毫秒内水合 1 个对象

objUserInfo.PortalID = portalId
objUserInfo.IsSuperUser = Convert.ToBoolean(dr("IsSuperUser"))
objUserInfo.UserID = Convert.ToInt32(dr("UserID"))
objUserInfo.Firstname = "FirstName"

但是，一旦我将数据读取器对象转换为字符串，平均需要 53 毫秒

objUserInfo.PortalID = portalId
objUserInfo.IsSuperUser = Convert.ToBoolean(dr("IsSuperUser"))
objUserInfo.UserID = Convert.ToInt32(dr("UserID"))
objUserInfo.Firstname = Convert.ToString(dr("FirstName"))

我也尝试水合 2 个字符串并勒死，它不会吹坏性能几乎与 1 根弦一样多？下面的代码平均只需要 57ms 来水合 1 个对象

objUserInfo.PortalID = portalId
objUserInfo.IsSuperUser = Convert.ToBoolean(dr("IsSuperUser"))
objUserInfo.UserID = Convert.ToInt32(dr("UserID"))
objUserInfo.Firstname = Convert.ToString(dr("FirstName"))
objUserInfo.LastName = Convert.ToString(dr("LastName"))

我知道很多人使用上面的语法来水合业务对象。有没有更有效/更快的方法来做到这一点？

编辑刚刚做了另一个测试，即在字符串上进行直接投射，它产生相同的慢速:( 53ms 只是为了进行投射。

objUserInfo.FirstName = DirectCast("alex", String)

原文

I am trying to hydrate a list of ~400 business objects and the performance becomes very slow when it needs to hydrate strings. It's taking in excess of 20secs to hydrate the 400 objects.

EDIT

We are using MySQL 5.1 and dotConnect for MySQL v5.0.12 as the data provider http://www.devart.com/dotconnect/mysql/

I did some benchmarks to narrow it down to the string types causing the problems. I started measuring the time from record 2 to n to ignore the time that might get taken up loading other assemblies.

The following code hydrates 1 object in 0ms

objUserInfo.PortalID = portalId
objUserInfo.IsSuperUser = Convert.ToBoolean(dr("IsSuperUser"))
objUserInfo.UserID = Convert.ToInt32(dr("UserID"))

This also hydrates 1 object in 0ms

objUserInfo.PortalID = portalId
objUserInfo.IsSuperUser = Convert.ToBoolean(dr("IsSuperUser"))
objUserInfo.UserID = Convert.ToInt32(dr("UserID"))
objUserInfo.Firstname = "FirstName"

However as soon as i do the convert on the datareader object to a string it takes an average of 53ms

objUserInfo.PortalID = portalId
objUserInfo.IsSuperUser = Convert.ToBoolean(dr("IsSuperUser"))
objUserInfo.UserID = Convert.ToInt32(dr("UserID"))
objUserInfo.Firstname = Convert.ToString(dr("FirstName"))

I also tried hydrating 2 strings and strangley it doesn't blow the performance out nearly as much as 1 string?
The following only takes an average of 57ms to hydrate 1 object

objUserInfo.PortalID = portalId
objUserInfo.IsSuperUser = Convert.ToBoolean(dr("IsSuperUser"))
objUserInfo.UserID = Convert.ToInt32(dr("UserID"))
objUserInfo.Firstname = Convert.ToString(dr("FirstName"))
objUserInfo.LastName = Convert.ToString(dr("LastName"))

I know that a lot of people use the above syntax to hydrate business objects. Is there a more efficient/faster way to do this?

EDIT
Just did another test which was to do a directcast on a string and it produces the same slow speeds :( 53ms just to do the cast.

objUserInfo.FirstName = DirectCast("alex", String)

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童话 2024-07-23 05:38:01

尝试一下：

而不是

objUserInfo.Firstname = Convert.ToString(dr("FirstName"))

使用

objUserInfo.Firstname = dr.GetString(2);

GetXXX 方法并依赖 Microsoft 来优化转换。（编辑：我怀疑 Convert.ToString(dr("FirstName")) 正在执行一些丑陋的隐式且耗时的转换和/或（取消）装箱操作。）
而不是使用字符串索引器（“FirstName”）使用数字索引器 (2)。这更快，但可读性较差。

编辑：亚历克斯发现了问题。不是选角问题！他对此的评论是：

好的，我已经找到问题所在了！
我正在使用 DotNetNuke 并填充一个
它的标准对象。问题
是当我设置 FirstName 时
它再次呼吁的财产
一个配置文件对象，它是什么
实际上需要这么长时间！没什么
与字符串转换有关或
铸造。

Give this a try:

Instead of

objUserInfo.Firstname = Convert.ToString(dr("FirstName"))

use

objUserInfo.Firstname = dr.GetString(2);

Use the GetXXX methods and rely on Microsoft to have optimized the conversion. (Edit: I am suspecting that Convert.ToString(dr("FirstName")) is doing some ugly implicit and time consuming conversions and/or (un)boxing operations.)
Instead of accessing the column with a string indexer ("FirstName") use a number indexer (2). That's faster, but less readable.

Edit: Alex found the problem. It's not a casting problem! His comment about it:

Alright i've tracked down the problem!
I'm using DotNetNuke and filling one
of it's standard objects. The problem
is that when i set the FirstName
property it makes another call out to
a profile object which is what
actually takes so long! It's nothing
to do with string conversion or
casting.

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