Question

I have a program that takes objects stored as XML in a database (basicly a message queue) and de-serializes them. Intermittently, I will get one of the following errors:

System.Runtime.InteropServices.ExternalException: Cannot execute a program. The command being executed was "C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\csc.exe" /noconfig /fullpaths @"C:\Documents and Settings\useraccount\Local Settings\Temp\lh21vp3m.cmdline".
   at System.CodeDom.Compiler.Executor.ExecWaitWithCaptureUnimpersonated(SafeUserTokenHandle userToken, String cmd, String currentDir, TempFileCollection tempFiles, String& outputName, String& errorName, String trueCmdLine)
   at System.CodeDom.Compiler.Executor.ExecWaitWithCapture(SafeUserTokenHandle userToken, String cmd, String currentDir, TempFileCollection tempFiles, String& outputName, String& errorName, String trueCmdLine)
   at Microsoft.CSharp.CSharpCodeGenerator.Compile(CompilerParameters options, String compilerDirectory, String compilerExe, String arguments, String& outputFile, Int32& nativeReturnValue, String trueArgs)
   at Microsoft.CSharp.CSharpCodeGenerator.FromFileBatch(CompilerParameters options, String[] fileNames)
   at Microsoft.CSharp.CSharpCodeGenerator.FromSourceBatch(CompilerParameters options, String[] sources)
   at Microsoft.CSharp.CSharpCodeGenerator.System.CodeDom.Compiler.ICodeCompiler.CompileAssemblyFromSourceBatch(CompilerParameters options, String[] sources)
   at System.CodeDom.Compiler.CodeDomProvider.CompileAssemblyFromSource(CompilerParameters options, String[] sources)
   at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, XmlSerializerCompilerParameters xmlParameters, Evidence evidence)
   at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, XmlSerializerCompilerParameters parameters, Assembly assembly, Hashtable assemblies)
   at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence)
   at System.Xml.Serialization.XmlSerializer.GenerateTempAssembly(XmlMapping xmlMapping, Type type, String defaultNamespace)
   at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)
   at System.Xml.Serialization.XmlSerializer..ctor(Type type)
   .....

Or I’ll get this one:

System.InvalidOperationException: Unable to generate a temporary class (result=1).
error CS0016: Could not write to output file 'c:\Documents and Settings\useraccount\Local Settings\Temp\nciktsd7.dll' -- 'Could not execute CVTRES.EXE.'

   at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, XmlSerializerCompilerParameters xmlParameters, Evidence evidence)
   at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, XmlSerializerCompilerParameters parameters, Assembly assembly, Hashtable assemblies)
   at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence)
   at System.Xml.Serialization.XmlSerializer.GenerateTempAssembly(XmlMapping xmlMapping, Type type, String defaultNamespace)
   at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)
   at System.Xml.Serialization.XmlSerializer..ctor(Type type)
   ....

The program process thousands of messages a day successfully, but I only get these errors maybe 2 or 3 times a day. They don’t appear to be correlated to any specific kind of message, just completely random.

Any idea what causes those errors and how to fix it?

ETA – Here’s the code that is causing the errors, in case that helps:

public class MessageContextBuilder<T> where T : MessageContextBase 
{
    private static IDictionary<string, XmlSerializer> SerializerCache { get; set; }
    public ILog Logger { get; set; }


    public MessageContextBuilder() {
        if (SerializerCache == null) SerializerCache = new Dictionary<string, XmlSerializer>();
        Logger = LogContextManager.Context.GetLogger<MessageContextBuilder<T>>();
    }

    public T BuildContextFromMessage(IEmailQueueMessage msg) {
        XmlSerializer serializer = GetSerializer(typeof(T));
        XmlReader r = XmlReader.Create(new StringReader(msg.MessageDetails));
        if (serializer.CanDeserialize(r)) {
            T rval = (T)serializer.Deserialize(r);
            rval.EmailAddress = msg.EmailAddress;
            rval.LocaleID = msg.LocaleID;
            rval.StoreID = msg.StoreID;
            rval.MessageID = msg.UniqueKey;
            return rval;
        } else {
            throw new ArgumentException("Cannot deserialize XML in message details for message #" + msg.UniqueKey);
        }
    }

    public XmlSerializer GetSerializer(Type t) {
        if (!SerializerCache.ContainsKey(t.FullName)) {
            SerializerCache.Add(t.FullName, new XmlSerializer(t)); // Error occurs here, in XmlSerializer constructor, intermittently
        }
        return SerializerCache[t.FullName];
    }
}

Answer 1

You can pre-create serializers: http://msdn.microsoft.com/en-us/library/bk3w6240%28v=VS.100%29.aspx Just give it a try. The next canonical candidate for such problems is your virus scanner. Your tool is writing to disc while creating serializers. I have seen virus scanner producing all kind of strange errors in such situations.