[IronPython] how to generate multiple concurrent scriptign engines?

surangika ranathunga lady_radsu at yahoo.com
Fri Apr 15 05:18:30 CEST 2011

Below is the exception I receive:
here, D:\PhD Work\Research\libomv\test\MonitorService\MonitorService\ExpectationMonitor.cs:line 88 refers to source.Execute(scope); in the below given code.

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceExce
ption: Object reference not set to an instance of an object.
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Collections.Generic.Dictionary`2.set_Item(TKey key, TValue value)
   at IronPython.Runtime.PythonContext.GetEqualSite(Type type)
   at IronPython.Runtime.CommonDictionaryStorage.UpdateHelperFunctions(Type t, Object key)
   at IronPython.Runtime.CommonDictionaryStorage.AddNoLock(Object key, Object value)
   at IronPython.Runtime.CommonDictionaryStorage.Add(Object key, Object value)
   at IronPython.Runtime.PythonDictionary.SetItem(Object key, Object value)
   at IronPython.Runtime.PythonDictionary.set_Item(Object key, Object value)
   at IronPython.Modules.PythonCopyReg.PerformModuleReload(PythonContext context, PythonDictionary dict)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle._InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
   at System.RuntimeMethodHandle.InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
   at IronPython.Runtime.PythonContext.CreateBuiltinModule(String moduleName, Type type, ModuleOptions options)
   at IronPython.Runtime.PythonContext.CreateBuiltinModule(String moduleName, Type type)
   at IronPython.Runtime.PythonContext.CreateBuiltinModule(String name)
   at IronPython.Runtime.PythonContext.GetBuiltinModule(String name)
   at IronPython.Runtime.Importer.ImportBuiltin(CodeContext context, String name)
   at IronPython.Modules.PythonCopyReg.EnsureModuleInitialized(CodeContext context)
   at IronPython.Modules.PythonCopyReg.GetDispatchTable(CodeContext context)
   at IronPython.Modules.PythonRegex.PerformModuleReload(PythonContext context,PythonDictionary dict)
   --- End of inner exception stack trace ---
   at Microsoft.Scripting.Actions.Calls.MethodCandidate.Caller.Call(Object[] args, Boolean& shouldOptimize)
   at IronPython.Runtime.Types.BuiltinFunction.BuiltinFunctionCaller`5.Call4(CallSite site, CodeContext context, TFuncType func, T0 arg0, T1 arg1, T2 arg2, T3 arg3)
   at System.Dynamic.UpdateDelegates.UpdateAndExecute6[T0,T1,T2,T3,T4,T5,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5)
   at IronPython.Runtime.Importer.Import(CodeContext context, String fullName, PythonTuple from, Int32 level)
   at IronPython.Runtime.Operations.PythonOps.ImportTop(CodeContext context, String fullName, Int32 level)
   at Microsoft.Scripting.Interpreter.FuncCallInstruction`4.Run(InterpretedFrame frame)
   at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame)
   at Microsoft.Scripting.Interpreter.LightLambda.Run2[T0,T1,TRet](T0 arg0, T1 arg1)
   at IronPython.Compiler.PythonScriptCode.RunWorker(CodeContext ctx)
   at IronPython.Compiler.PythonScriptCode.Run(Scope scope)
   at IronPython.Compiler.RuntimeScriptCode.InvokeTarget(Scope scope)
   at IronPython.Compiler.RuntimeScriptCode.Run(Scope scope)
   at Microsoft.Scripting.SourceUnit.Execute(Scope scope, ErrorSink errorSink)
   at Microsoft.Scripting.SourceUnit.Execute(Scope scope)
   at Microsoft.Scripting.Hosting.ScriptSource.Execute(ScriptScope scope)
   at MonitorService.ExpectationMonitor.Initialize(String rule) in D:\PhD Work\Research\libomv\test\MonitorService\MonitorService\ExpectationMonitor.cs:line 88

--- On Thu, 14/4/11, Jeff Hardy <jdhardy at gmail.com> wrote:

From: Jeff Hardy <jdhardy at gmail.com>
Subject: Re: [IronPython] how to generate multiple concurrent scriptign engines?
To: "Discussion of IronPython" <users at lists.ironpython.com>
Cc: "surangika ranathunga" <lady_radsu at yahoo.com>
Received: Thursday, 14 April, 2011, 7:35 AM

As long as you have a ScriptScope per thread, you should be able to
share the ScriptEngine & Runtime between threads.

What is the exception that you are getting? If it's a GUI program,
remember that UI elements can only be manipulated from the main

- Jeff

On Thu, Apr 14, 2011 at 1:02 AM, surangika ranathunga
<lady_radsu at yahoo.com> wrote:
> Hi,
> I am using Ironpython to connect to a legacy python code from C#.
> I am not fully familiar with Ironpython, but managed to get it working for a single-threaded application.
> This is how I implemented this:
>                 ScriptEngine engine = Python.CreateEngine();
>                 ScriptRuntime runtime = engine.Runtime;
>                 ScriptScope scope = runtime.CreateScope();
>                 ops = engine.Operations;
>                 ScriptSource source = engine.CreateScriptSourceFromFile("ironpython.py");
>                 source.Execute(scope);
>                 string class_param = rule;
>                 object[] parameters = new object[1];
>                 parameters[0] = class_param;
>                 object klass = scope.GetVariable("model_checker");
>                 object instance = ops.Invoke(klass, parameters);
>                 method = ops.GetMember(instance, "check_model");
> Now I want to make my application multi-threaded, and I want to have concurrently running scripting engines. Essentially, these engines should access the same underlying python code, and hence these scripting engines are identical to each other.
> Without any change, the above code works fine for most of the time for a multi-threaded application. However, there is an exception that appears from time to time, and I suspect that it is due to a concurrency issue.
> Is there anything specific that I should do to generate multiple scripting engines running in separate threads without interfering with each other?
> any ideas greatly appreciated
> _______________________________________________
> Users mailing list
> Users at lists.ironpython.com
> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
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