Exceptions in customizers __jclass_init__ crash the JVM

[astrelsky]

Below is a silly example to reproduce the problem. I just picked a class at random that didn't have a customizer provided by jpype. There is no purpose for a customizer for this class other then demonstrating the issue.

import jpype
from jpype.imports import *

jpype.startJVM()

@jpype.JImplementationFor("java.io.Console")
class Console:
    def __jclass_init__(self):
        raise Exception("hi")


from java.io import Console

The crash appears to be from an uncaught exception in PyJPClass_hook around (pyjp_class.cpp:1200)

[Thrameos]

I did not get a crash on my machine. Perhaps we need more details in terms of versions or arch....

Traceback (most recent call last):
  File "test3.py", line 11, in <module>
    from java.io import Console
  File "<frozen importlib._bootstrap>", line 1075, in _handle_fromlist
Exception: hi

[astrelsky]

I did not get a crash on my machine. Perhaps we need more details in terms of versions or arch....

Traceback (most recent call last):
  File "test3.py", line 11, in <module>
    from java.io import Console
  File "<frozen importlib._bootstrap>", line 1075, in _handle_fromlist
Exception: hi

Windows 10 and 11. JDK 21, 22 and JDK 8. Python 3.11.7, 3.12.1 and 3.8.10. I tried the lowest supported versions of Java and Python that had pre-built wheels for Jpype1 (to eliminate variables), that I could get my hands on.

Also I had to debug the setup.py script and step through it to change the flags to get a release build with debug info. If you do setup.py build_ext -g it will exit as soon as you import jpype and complain about the gil. I did this on a machine I can't share from but if you need it I'd be more than happy to do it on my laptop and provide a copy of the pyd and pdb

[Thrameos]

Got it. Will try though I have a few other items in the queue already.

Edit: I was successfully able to replicate the issue with Windows 11 so I have a place to work from.

[Thrameos]

I understand the issue. The problem is to prevent name mangling we are declaring functions as extern "C" but also supplying /EHsc which means that they are not allowed to throw. Because of this we end up with an exception which is going from C++ to C++ failing. Either we have to remove all extern "C" declarations or switch to ``/EHa /EHs" when compiling.

The problem was compounded because the extern "C" was in the header rather than definition. Thus absolutely nothing appears wrong in the code.

[Thrameos]

A PR with the fix is posted. It will be included in the next release. Though I haven't seen any responses from the maintainer in a while so not sure when it will get reviewed.

[astrelsky]

A PR with the fix is posted. It will be included in the next release. Though I haven't seen any responses from the maintainer in a while so not sure when it will get reviewed.

Nice, that was quick. Thank you very much.

[Thrameos]

It was a one liner. So not that impressive. The longer job would be verifying all of the other calls in module dont have the same problem.

[astrelsky]

It was a one liner. So not that impressive. The longer job would be verifying all of the other calls in module don't have the same problem.

I did take a quick look yesterday and I think everything else is ok.