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StringBuilder vs XmlTextWriter

开发者 https://www.devze.com 2022-12-23 17:51 出处:网络
I am trying to squeeze as much performance as i can from a custom Ht开发者_如何学编程tpHandler that serves Xml content.

I am trying to squeeze as much performance as i can from a custom Ht开发者_如何学编程tpHandler that serves Xml content.

I' m wondering which is better for performance. Using the XmlTextWriter class or ad-hoc StringBuilder operations like:

StringBuilder sb = new StringBuilder("<?xml version="1.0" encoding="UTF-8" ?>");    
sb.AppendFormat("<element>{0}</element>", SOMEVALUE);

Does anyone have first hand experience?


As Josh said, this is a micro-optimization that you shouldn't even consider if you haven't proved its necessity. It's also really not difficult to test:

static void Main(string[] arguments)
{
    const int iterations = 100000;

    Stopwatch sw = new Stopwatch();
    sw.Start();
    string s = CreateUsingStringBuilder("content", iterations);
    sw.Stop();
    Console.WriteLine(String.Format("CreateUsingStringBuilder: {0}", sw.ElapsedMilliseconds));

    sw.Reset();
    sw.Start();
    s = CreateUsingXmlWriter("content", iterations);
    sw.Stop();
    Console.WriteLine(String.Format("CreateUsingXmlWriter: {0}", sw.ElapsedMilliseconds));

    Console.ReadKey();
}

private static string CreateUsingStringBuilder(string content, int iterations)
{
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < iterations; i++ )
        sb.AppendFormat("<element>{0}</element>", content);

    return sb.ToString();
}

private static string CreateUsingXmlWriter(string content, int iterations)
{
    StringBuilder sb = new StringBuilder();
    using (StringWriter sw = new StringWriter(sb))
    using (XmlWriter xw = XmlWriter.Create(sw))
    {
        xw.WriteStartElement("root");
        for (int i = 0; i < iterations; i++ )
            xw.WriteElementString("element", content);
        xw.WriteEndElement();
    }
    return sb.ToString();
}

Not only is the XmlWriter version consistently faster by a millisecond or two, it produces well-formed XML, which the other method doesn't.

But both methods are creating 100,000-element XML documents in about 60 milliseconds on my two-year-old laptop, an amount of time that dwindles into insignificance compared with the time it will take to push that much data over the network.


I agree that XmlWriter is better for code maintainability, but if we are talking about performance optimization, you should avoid both XmlWriter and StringBuilder.AppendFormat, because using a formatter ruins performance.

changing

sb.AppendFormat("<element>{0}</element>", content);

to

sb.Append("<element>").Append(content).Append("</element>");

makes the StringBuilder version 2.5 times faster then the other from Robert's answer.


When SOMEVALUE has a & or < in it, this approach will get you into trouble. Use xml-aware classes to to generate xml. Have a read of HOWTO Avoid Being Called a Bozo When Producing XML.


Honestly until you really, really, really, really, really need to care about performance... don't.

Go with the more maintainable solution first, and only compromise when performance becomes a measurable issue. XmlTextWriter offers you the benefit of "Knowing" about how Xml is supposed to work. StringBuilder does not, and is therefore error prone. You don't want to spend a day tracking down a malformed node somewhere in your gnarly stringbuilder code.

Let the framework work for you.

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