[IronPython] IronPython and Threads

[Dan Eloff]

> For now, you'll probably want to wrap any function used as a thread "main" in a try/except and do something to log the error in the exception handler.

I guess that's what I need to do, seeing as I don't create the thread,
Silverlight does. Logging/printing is out because it's silverlight.

> printing to std out isn't too useful in Silverlight but we could also look
> at having that display in Silverlight somehow too.

Tell me about it, I'm going to have to think very carefully just to
find a way to see this error that's bringing everything down. It would
be great if you guys think of something for Silverlight, (more likely
just pass the task on to one of the Silverlight guys (Jimmy, are you
reading this)) because it just silently catches the error, and it's
very difficult to try to display it, depending on where/when it
occurs.

-Dan


On Sun, Jun 8, 2008 at 12:55 PM, Dino Viehland
<dinov at exchange.microsoft.com> wrote:
> If you use the thread module we will wrap the newly created thread in a
> try/except for you and print to std-out when the unhandled exception
> occurs.  That way we match the CPython behavior but you can get the standard
> .NET behavior if you want by going to System.Threading.  Unfortunately
> printing to std out isn't too useful in Silverlight but we could also look
> at having that display in Silverlight somehow too.
>
>
>
> From: users-bounces at lists.ironpython.com
> [mailto:users-bounces at lists.ironpython.com] On Behalf Of Curt Hagenlocher
> Sent: Sunday, June 08, 2008 10:04 AM
> To: Discussion of IronPython
> Subject: Re: [IronPython] IronPython and Threads
>
>
>
> Under CLR 2, any uncaught exception in a thread other than the primary
> thread will take down the entire process.  This is not specific to
> IronPython.  I don't know what the Silverlight CLR will do under these
> circumstances.
>
>
>
> You could make a case that a Python-initiated thread shouldn't terminate the
> process given that CPython wouldn't do the same, but as far as I know, we
> haven't gotten any requests along those lines.  For now, you'll probably
> want to wrap any function used as a thread "main" in a try/except and do
> something to log the error in the exception handler.
>
> On Sun, Jun 8, 2008 at 8:23 AM, Dan Eloff <dan.eloff at gmail.com> wrote:
>
> I'm having a problem debugging some issues that I suspect are thread
> related in Silverlight. My application is failing silently, so I have
> no way to be sure yet. Is it possible that exceptions in a background
> thread are quietly swallowed? I'm pretty sure my callback is being
> called, but all that is in it right now is a raise statement.
>
> I've enabled debug.
> <param name="initParams" value="debug=true,reportErrors=errorLocation" />
>
> I've been trying to explore Threads a little more with IronPython to
> see what might be the problem, but even there I'm not having much
> luck. I could swear this used to work in Beta 1. Now it crashes the
> interpreter.
>
> IronPython 2.0 Beta (2.0.0.2000) on .NET 2.0.50727.1433
> Copyright (c) Microsoft Corporation. All rights reserved.
>>>> from System.Threading import Thread, ThreadStart
>>>> def foo():
> ...     raise ValueError
> ...
>>>> t = Thread(ThreadStart(foo))
>>>> t.Start()
>>>>
> Unhandled Exception: System.ArgumentException
>   at foo$1##16(Closure )
>   at _stub_##25(Closure , CallSite , CodeContext , Object )
>   at Microsoft.Scripting.Utils.InvokeHelper`5.Invoke(Object arg0,
> Object arg1, Object arg2, Object arg3)
>   at Microsoft.Scripting.Utils.ReflectedCaller.InvokeInstance(Object
> instance, Object[] args)
>   at
> Microsoft.Scripting.Actions.ActionBinder.UpdateSiteAndExecute[T](CodeContext
> context, CallSite`1 site, Object[] args)
>   at Microsoft.Scripting.Actions.UpdateDelegates.Update1[T0,TRet](CallSite
> site, CodeContext context, T0 arg0)
>   at System.Void(), using PythonBinder##20(Closure )
>   at System.Threading.ExecutionContext.Run(ExecutionContext
> executionContext, ContextCallback callback, Object state)
>   at System.Threading.ThreadHelper.ThreadStart()
>
> What's going wrong? How should I be doing this?
>
> Thanks,
> -Dan
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