[BUG]: `cuda.core` Event failed to complete cleanup properly

[yangcal]

Is this a duplicate?

• I confirmed there appear to be no duplicate issues for this bug and that I agree to the Code of Conduct

Type of Bug

Runtime Error

Component

cuda.core

Describe the bug

In our project, one of the custom object holds a reference to the cuda.core.experimental.Event and the following occurred during resource cleanup stage, e.,g

[2025-07-31T06:01:25.076Z] Traceback (most recent call last):
[2025-07-31T06:01:25.076Z] File "cuda/core/experimental/_event.pyx", line 114, in cuda.core.experimental._event.Event.close
[2025-07-31T06:01:25.076Z] AttributeError: 'NoneType' object has no attribute 'cuEventDestroy'
[2025-07-31T06:01:25.076Z] Exception ignored in: 'cuda.core.experimental._event.Event.del'
[2025-07-31T06:01:25.076Z] Traceback (most recent call last):
[2025-07-31T06:01:25.076Z] File "cuda/core/experimental/_event.pyx", line 114, in cuda.core.experimental._event.Event.close
[2025-07-31T06:01:25.076Z] AttributeError: 'NoneType' object has no attribute 'cuEventDestroy'
[2025-07-31T06:01:25.076Z] Traceback (most recent call last):
[2025-07-31T06:01:25.076Z] File "cuda/core/experimental/_event.pyx", line 114, in cuda.core.experimental._event.Event.close
[2025-07-31T06:01:25.076Z] AttributeError: 'NoneType' object has no attribute 'cuEventDestroy'
[2025-07-31T06:01:25.076Z] Exception ignored in: 'cuda.core.experimental._event.Event.del'
[2025-07-31T06:01:25.076Z] Traceback (most recent call last):
[2025-07-31T06:01:25.076Z] File "cuda/core/experimental/_event.pyx", line 114, in cuda.core.experimental._event.Event.close
[2025-07-31T06:01:25.076Z] AttributeError: 'NoneType' object has no attribute 'cuEventDestroy'

On our side, we had to explicitly release the reference to the Event object and then the issue was resolved, e.g,

def free(self):
     self.event = None # without this, the error occurred in an MPI simulation

How to Reproduce

This is part of an integrated example and we don't have a minimal reproducer.

Expected behavior

del should properly execute to free the Event.

Operating System

No response

nvidia-smi output

No response

[brandon-b-miller]

I'm able to reproduce this with a Stream object with the following code:

from cuda.core.experimental import Device
from numba import cuda

@cuda.jit
def kernel():
    pass


device = Device()
device.set_current()
stream = device.create_stream()

kernel[1, 1]()

  File "cuda/core/experimental/_stream.pyx", line 199, in cuda.core.experimental._stream.Stream.close
AttributeError: 'NoneType' object has no attribute 'cuStreamDestroy

[rwgk]

We have only three __del__ in cuda_core:

 $ git grep __del__
cuda/core/experimental/_event.pyx:    def __del__(self):
cuda/core/experimental/_memory.pyx:    def __del__(self):
cuda/core/experimental/_stream.pyx:    def __del__(self):

An easy approach could be to inspect the three close() implementations, and check is not None for all variables used.

I took a quick look, it seems very straightforward in all three cases.

[rwgk]

I forgot to mention: I'm assuming, if the interpreter is shutting down, "complete cleanup" isn't critical.