Thanks for the info. Looking at this, an idea came to mind that might be worth looking into: Is GenerateReport() called on a per-request basis as a web service? If so, you might try initializing the python engine once at startup rather than per-request. I'm actually not sure that reinitializing the engine in the same process will work in any reliable way (there are allegations on the python lists that this is a grey area in regard to the C python runtime). If nothing else, it could be causing two instances of Reporting to try to initialize the engine at the same time. Since they are both essentially initializing a single C runtime, I could imagine the GIL getting balled up in that case pretty easily. -Brian
-----Original Message----- From: Matthew Pontefract [mailto:MP@credaris.com] Sent: Tuesday, June 06, 2006 11:37 AM To: Brian Lloyd; pythondotnet@python.org Subject: RE: [Python.NET] .NET 2 and hang with AcquireLock
Thanks for your reply Brian - I have been playing around with this a fair bit. I checked out the source code from Subversion; the revision from 2nd June built with no problems and so I now have a .NET 2 build which appears to work well from the console etc.
Using this from my C# web service exhibits the same behaviour as before however! The problem is really quite tricky because in fact it is wider than I previously suspected: the web service will successfully acquire the lock once or twice in a row, but will then hang at the AcquireLock call regardless of whether a Python exception had been raised in code or not.
I don't think any of the C# code would have been called again (and I kept tabs on calls to acquire and drop the lock), nor is there any re-entrant code.
This prompted me to change my approach to a rather more satisfactory one anyway: I use ZSI to create a separate web service from python directly and call that web service from my C# app. I use PythonNet because I want to use business code available in .NET assemblies. Thanks to PythonNet it's been a breeze to use Python in what is otherwise a very C# environment - I'm really pleased.
Even though I've changed tack, when I have time I'll get a debugger onto the PythonNet code and try and trace this further - I'll post back if I get anywhere. It would be interesting to know if it's something peculiar to me!
For your information, as requested, the code where the problem occurred is as follows (it's all a touch noddy - various permutations of this were tried, so that's why the gs lock object rather bizarrely ended up static etc...):
public class Reporting { private static IntPtr gs; public static void GenerateReport(String report) { if (!PythonEngine.IsInitialized) { PythonEngine.Initialize(); gs = PythonEngine.AcquireLock(); try {
PythonEngine.RunSimpleString("import sys");
PythonEngine.RunSimpleString("sys.path.append('g:/pyccolo')");
PythonEngine.RunSimpleString("from report.server_init import *");
PythonEngine.RunSimpleString("print(sys.path)");
PythonEngine.RunSimpleString("o.flush()"); } finally { PythonEngine.ReleaseLock(gs); } }
gs = PythonEngine.AcquireLock(); try {
PythonEngine.RunSimpleString("runReport('"+report+"')");
PythonEngine.RunSimpleString("o.flush()"); } finally { PythonEngine.ReleaseLock(gs); } } }
Regards Matthew
-----Original Message----- From: Brian Lloyd [mailto:Brian.Lloyd@revolution.com] Sent: 06 June 2006 14:24 To: Matthew Pontefract; pythondotnet@python.org Subject: RE: [Python.NET] .NET 2 and hang with AcquireLock
Hi Matthew -
This is a tough kind of problem to debug through email ;)
Is there any chance that the exceptions you raise cause any of your C# to be called again?
If not, if there is any way you can distill your code to a relatively small example that demonstrates the problem, send it to me and I'll take a look.
-Brian
-----Original Message----- From: pythondotnet-bounces@python.org [mailto:pythondotnet-bounces@python.org] On Behalf Of Matthew Pontefract Sent: Tuesday, June 06, 2006 6:08 AM To: pythondotnet@python.org Subject: [Python.NET] .NET 2 and hang with AcquireLock
Hello
I have a question pertaining to running Python NET under .NET version 2 which, admittedly, is not the version for which the packages are built.
All works just fine - I am using the PythonEngine inside a web service, acquiring the GIL before operations, releasing it in a 'finally' block afterwards. This is fine provided no python exceptions are raised in the Python code. Even though the GIL is released in the C#, a subsequent call to AcquireLock will hang as if waiting for it to be released. No calls to acquirelock have been made between the last call to release the GIL and the call that hangs.
Has anyone else had this problem?
I am using Python 2.4
Regards
Matthew
Dr Matthew Pontefract
Credaris Portfolio Management
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