为什么删除包含对象引用的集合时不调用“obj.__del__（）”

问：

我正在尝试构建一个子类以在我的桌面中使用多个 GPU。Process

class GPUProcess(mp.Process):
    used_ids: list[int] = []
    next_id: int = 0

    def __init__(self, *, target: Callable[[Any], Any], kwargs: Any):
        gpu_id = GPUProcess.next_id
        if gpu_id in GPUProcess.used_ids:
            raise RuntimeError(
                f"Attempt to reserve reserved processor {gpu_id} {self.used_ids=}"
            )
        GPUProcess.next_id += 1
        GPUProcess.used_ids.append(gpu_id)
        self._gpu_id = gpu_id

        # Define target process func with contant gpu_id
        def _target(**_target_kwargs):
            target(
                **_target_kwargs,
                gpu_id=self.gpu_id,
            )
        super(GPUProcess, self).__init__(target=_target, kwargs=kwargs)

    @property
    def gpu_id(self):
        return self._gpu_id

    def __del__(self):
        GPUProcess.used_ids.remove(self.gpu_id)

    def __repr__(self) -> str:
        return f"<{type(self)} gpu_id={self.gpu_id} hash={hash(self)}>"
# Test creation
def test_process_creation():
    # Expect two gpus
    def dummy_func(*args):
        return args
    processes = []
    for _ in range(2):
        p = GPUProcess(
            target=dummy_func,
            kwargs=dict(a=("a", "b", "c")),
        )
        processes.append(p)
    
    for p in processes:
        p.start()

    for p in processes:
        p.join()

    del processes

    assert GPUProcess.used_ids == [], f"{GPUProcess.used_ids=}!=[]"

if __name__ == "__main__":
    test_process_creation()

__del__不为第二个进程调用。

AssertionError: GPUProcess.used_ids=[1]!=[]

为什么不叫第二个？__del__

稍后，我将利用这个类来运行大量有效负载，每个 GPU 使用一个有效负载和一个使用关键字来决定使用设备的函数。这在 Python 中是否明智？mp.PoolGPUProcessgpu_id