XmlSerializer startup HUGE performance loss on 64bit systems

I am experiencing a really HUGE performance loss while calling a simple XmlSerializer.Deserizlize() on a class with lots of fields.

NOTE: I'm writing the code without Visual Studio, at home, so it may have some errors.

My serializable class is flat and has hundreds of fields:

[Serializable]
class Foo
{
    public Foo() { }

    [XmlElement(ElementName = "Field1")]
    public string Field1;

    // [...] 500 Fields defined in the same way

    [XmlElement(ElementName = "Field500")]
    public string Field500;
}

My application deserializes an input string (even small):

 StringReader sr = new StringReader(@"<Foo><Field1>foo</Field1></Foo>");
 XmlSerializer serializer = new XmlSerializer(typeof(Foo));
 object o = serializer.Deserialize(sr);

Running the application in 32bit systems (or with 32bit forced with corflags.exe), the code takes about ONE SECOND the first time (temp serialization class generation, and all...), then it's close to 0.

Running the application in 64bit systems, the code takes ONE MINUTE the first time, then it's close to 0.

What could possibly hang the system for such a long time, during the first execution of an XmlSerializer, for a big class, in a 64bit system?

Right now I'm not sure if I have to blame temp class generation/remove, xml name table initialization, CAS, Windows Search, AntiVirus, or Santa Claus...

SPOILERS

Here are my tests, don't read this if you don't want to be sidetracked by my (possible) analysys mistakes.

Running the code the from Visual Studio debugger makes the code run FAST even in 64 bit systems
Adding the (totally undocumented) system.diagnostic switch "XmlSerialization.Compile", which prevents the system from removing the serialization tem

.net 64-bit xmlserializer

Edit Report

To clarify the "XmlSerialization.compile" this is what it's happening:

If we run the code without a .config file on 64 bit it's slow.

If we add the following section to the .config file for the application

<configuration>
   <system.diagnostics>
     <switches>
        <add name="XmlSerialization.Compilation" value="4"/>
     </switches>
   </system.diagnostics>
</configuration>

The result is the following:

.cs file, DLL and PDB file for the serializer are left in the temp folder
serializer start quicky, it's still slower than on 32 bit but definitively acceptable (1-2 seconds instead of 60)

Maybe creating the DLL in debug mode (because there are PDB files available) change the behavior of the JIT compiler making it fast again...

answered 2010-11-10T08:32:39.687

XmlSerializer startup HUGE performance loss on 64bit systems

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