Attempt to make SqlWorkload.exe a service fails with 'Type cannot be instantiated'

[schnorea]

I'm trying to run the commandline tool SqlWorkload.exe in mono in a docker container but I am getting an error when the Listener is getting instanced.

Process:

• Stand up mono docker container (have used this before for compiling C# commandline apps)
• git cloned WorkloadTools repo into container
• Edit WorkloadTools.sln so the SqlWorkload and WorkloadTools projects are the only ones in the sln file.
• run nuget restore
• run msbuild /p:Configuration=Debug WorkloadTools.sln it compiles to x64
• Compiles with no errors or warnings
• run mono --debug SqlWorkload.exe
• Executes without SqlWorkload.json to print help screen
• Execution with the SqlWorkload.json file below, prints out the exception/backtrace below.

SqlWorkload.json

{
    "Controller": {

        "Listener":
        {
            "__type": "ExtendedEventsWorkloadListener",
            "ConnectionInfo":
            {
                "ServerName": "192.168.2.225",
                "DatabaseName": "MontyPython",
                "SchemaName": "dbo",
                "UserName": "sa",
                "Password": "PA55vv0rD"
            }
            //,
            //"DatabaseFilter": "benchmark",
            //"TraceRolloverCount": 100,
            //"TimeoutMinutes": 10
        },
        "Consumers":
        [
            {
                "__type": "WorkloadFileWriterConsumer",
                "OutputFile": "first_capture.sqlite"
            }
       ]
    }
}

Error message

root@6c93561df728:/WorkloadTools/SqlWorkload/bin/x64/Debug# mono --debug SqlWorkload.exe
Info - SqlWorkload.Program : SqlWorkload, Version=1.7.1.0, Culture=neutral, PublicKeyToken=null 1.7.1
Info - SqlWorkload.Program : Reading configuration from '/WorkloadTools/SqlWorkload/bin/x64/Debug/SqlWorkload.json'
Error - SqlWorkload.Program : System.FormatException: Unable to load configuration from '/WorkloadTools/SqlWorkload/bin/x64/Debug/SqlWorkload.json'. The file contains semantic errors. ---> System.ArgumentException: Type cannot be instantiated
Parameter name: type
  at (wrapper managed-to-native) System.Runtime.Remoting.Activation.ActivationServices.AllocateUninitializedClassInstance(System.Type)
  at System.Runtime.Serialization.FormatterServices.nativeGetUninitializedObject (System.RuntimeType type) [0x00000] in <de882a77e7c14f8ba5d298093dde82b2>:0 
  at System.Runtime.Serialization.FormatterServices.GetUninitializedObject (System.Type type) [0x00035] in <de882a77e7c14f8ba5d298093dde82b2>:0 
  at WorkloadTools.Util.ModelConverter.Deserialize (System.Collections.Generic.IDictionary`2[TKey,TValue] dictionary, System.Type type, System.Web.Script.Serialization.JavaScriptSerializer serializer) [0x0000e] in /WorkloadTools/WorkloadTools/Util/ModelConverter.cs:51 
  at WorkloadTools.Util.ModelConverter.Deserialize (System.Collections.Generic.IDictionary`2[TKey,TValue] dictionary, System.Type type, System.Web.Script.Serialization.JavaScriptSerializer serializer) [0x001c0] in /WorkloadTools/WorkloadTools/Util/ModelConverter.cs:89 
  at WorkloadTools.Util.ModelConverter.Deserialize (System.Collections.Generic.IDictionary`2[TKey,TValue] dictionary, System.Type type, System.Web.Script.Serialization.JavaScriptSerializer serializer) [0x001c0] in /WorkloadTools/WorkloadTools/Util/ModelConverter.cs:89 
  at System.Web.Script.Serialization.JavaScriptSerializer.ConvertToType (System.Object obj, System.Type targetType) [0x0003c] in <258c42715fee4479b0f6509f80f9cdc7>:0 
  at System.Web.Script.Serialization.JavaScriptSerializer.ConvertToType[T] (System.Object obj) [0x0000d] in <258c42715fee4479b0f6509f80f9cdc7>:0 
  at System.Web.Script.Serialization.JavaScriptSerializer.Deserialize[T] (System.String input) [0x00008] in <258c42715fee4479b0f6509f80f9cdc7>:0 
  at WorkloadTools.Config.SqlWorkloadConfig.LoadFromFile (System.String path) [0x00066] in /WorkloadTools/WorkloadTools/Config/SqlWorkloadConfig.cs:50 
   --- End of inner exception stack trace ---
  at WorkloadTools.Config.SqlWorkloadConfig.LoadFromFile (System.String path) [0x00076] in /WorkloadTools/WorkloadTools/Config/SqlWorkloadConfig.cs:54 
  at SqlWorkload.Program.Run (SqlWorkload.Options options) [0x00198] in /WorkloadTools/SqlWorkload/Program.cs:102 
  at SqlWorkload.Program.Main (System.String[] args) [0x000c2] in /WorkloadTools/SqlWorkload/Program.cs:47 

In a previous attempt at debugging the issue I put in print statements to determine where things went sideways and what the type was that it was not able to instance.

The source seems to be at the p = System.Runtime.Serialization.FormatterServices.GetUninitializedObject(type); line in the ModelConverter.cs file as seen below.

The type it was attempting to get (and seems to fail at) was WorkloadTools.WorkloadListener. It did fine with the first pass were it got the WorkloadTools.WorkloadController.

        public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
        {
            object p;
            try
            {
                // try to create the object using its parameterless constructor
                p = Activator.CreateInstance(type);
            }
            catch {
                // try to create the object using this scary initializer that 
                // doesn't need the parameterless constructor
                p = System.Runtime.Serialization.FormatterServices.GetUninitializedObject(type);
            }

I verified the DB could be reached via the connection string I provided (the one above is modified) using sqlcmd from a docker container so I am pretty sure that works. Hunting around for what setup would cause GetUninitializedObject to fail didn't turn up anything.

Any ideas what might cause this would be appreciated.

[spaghettidba]

Hi, this looks like a very tricky issue.
I never have tried to make WorkloadTools compile and run under Mono. Seems to me that System.Runtime.Serialization.FormatterServices.GetUninitializedObject(type); is implementation dependent. I don't think I can add much to your analysis, except that the exception is happening outside my code, probably in native code.
Sorry, I wish I could help you but this is outside my area of expertise

[schnorea]

I appreciate the reply. I'm not as strong in C# either. I might take a look at creating a config file parser that is simpler when I get some time.

Another question: I have read alot about WorkloadTool and it seems like its can keep up with pretty high transacation rates. Any idea of the highest rate recorded to date might be?

Thank you

[spaghettidba]

Hi, sorry for the delay, I got a few health issues. I honestly don't know. I have been told it managed to capture the workload on servers with 20K batches per second. I have experienced myself over 3K batches replayed per second.