IronPython stops to work with module (json) after a while

Python 2.7.11 on .NET Core 3.1 hosted in Azure on service fabric. Initially everything works, after a while a certain library fails, namely json

{
    "ClassName": "System.MissingMemberException",
    "Message": "'module' object has no attribute 'dumps'",
    "Data": null,
    "InnerException": null,
    "HelpURL": null,
    "StackTraceString": "   at IronPython.Runtime.Operations.PythonOps.ObjectGetAttribute(CodeContext context, Object o, String name)\r\n   at IronPython.Runtime.PythonModule.__getattribute__(CodeContext context, String name)\r\n   at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1)\r\n   at Microsoft.Scripting.Interpreter.FuncCallInstruction`5.Run(InterpretedFrame frame)\r\n   at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame)\r\n   at Microsoft.Scripting.Interpreter.LightLambda.Run2[T0,T1,TRet](T0 arg0, T1 arg1)\r\n   at IronPython.Compiler.PythonScriptCode.RunWorker(CodeContext ctx)\r\n   at Ic.RestMocker.Core.Scripting.ScriptSession.Execute(String script, Dictionary`2 scope) in I:\\agent\\_work\\817\\s\\Ic.RestMocker.Core\\Scripting\\ScriptSession.cs:line 93\r\n   at Ic.RestMocker.Core.Controllers.ScriptsController.Post() in I:\\agent\\_work\\817\\s\\Ic.RestMocker.Core\\Controllers\\ScriptsController.cs:line 38",
    "RemoteStackTraceString": null,
    "RemoteStackIndex": 0,
    "ExceptionMethod": null,
    "HResult": -2146233070,
    "Source": "IronPython",
    "WatsonBuckets": null,
    "MMClassName": null,
    "MMMemberName": null,
    "MMSignature": null
}

If I create a script like

import sys
sys.path

Output is

[
    "D:\\SvcFab\\_App\\RestMocker.ApplicationType_App66\\RestMocker.ApiPkg.Code.1.0.0.RestMocker_master_20201123.2\\pylib"
]

Which is the correct path to pylib

[AndersMalmgren]

This is output from your commands btw, will test again when it breaks

11/23/2020, 7:25:34 PM

TRACE
['JSONDecoder', 'JSONEncoder', '__all__', '__author__', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__', '__version__', '_default_decoder', '_default_encoder', 'decoder', 'dump', 'dumps', 'encoder', 'load', 'loads', 'scanner']
Severity level: Information
11/23/2020, 7:25:34 PM

TRACE
<module 'json' from 'D:\SvcFab\_App\RestMocker.ApplicationType_App66\RestMocker.ApiPkg.Code.1.0.0.RestMocker_master_20201123.4\pylib\json\__init__.py'>
Severity level: Information

[AndersMalmgren]

@slozier

I have been able to repro! The total failure of the module only happens about 1 each 5 or 10 time for above test. So I rewrote my test to this, and now it fails every time

            var session = provider.GetService<IScriptSession>();
            var script = @"import json
json.dumps({ 'Foobar': 1 }, ensure_ascii = False)";

            foreach (var foo in Enumerable.Range(0, 10))
            {

                var error = false;

                while (!error)
                {
                    try
                    {
                        Parallel.ForEach(Enumerable.Range(1, 1000),
                            new ParallelOptions {MaxDegreeOfParallelism = Environment.ProcessorCount},
                            i => session.Execute(null, script));
                    }
                    catch (Exception e)
                    {
                        Console.WriteLine(e.Message);
                        error = true;
                    }
                }

                var result = session.Execute(null, script);
                Assert.IsNotNull(result);
            }

            await Database.Instance.TakeDown();
            await Database.Instance.WaitForCleanup();
        }

My solution

            var hash = script.GetHashCode();
            if (!_importLookup.ContainsKey(hash))
                _importLookup[hash] = script.Contains("import", StringComparison.InvariantCultureIgnoreCase);
            var locked = _importLookup[hash];

            if (locked)
                _importLock.Wait();

            object result;

            try
            {

                result = compiled.Execute(_engine.CreateScope(scope));
            }
            finally
            {
                if (locked)
                    _importLock.Release();
            }