Always remove finished transient_tasks.

[gmsoft-tuxicoman]

The original code only remove tasks from self.transient_tasks when an exception occurs.

This lead to a high CPU scenario when the for loop checks all the tasks for their done status as the task list keeps growing forever.

This should fixes #236.

[BenjiU]

It also works on my side.

I've a question to your change: you remove all tasks that are 'done', the "exeption print" will not work any longer, right?

    async def _remove_finished_transient_tasks(self) -> None:
        while True:
            await asyncio.sleep(1)
            finished_tasks = [x for x in self.transient_tasks if x.done()]
            if not finished_tasks:
                continue
==> Your fix will remove all tasks that are "done" even the one with exceptions.
            for task in finished_tasks:
                self.transient_tasks.remove(task)
<==
            results = await asyncio.gather(*finished_tasks, return_exceptions=True)
            for i, exception in [
                x for x in enumerate(results) if isinstance(x[1], Exception)
                    raise exception
                except Exception:  # pylint: disable=broad-except
                    _LOG.exception("Exception in task: %r:", task)
==> you removed
                finally:
                    self.transient_tasks.remove(task)
<== 

So we should first print the exceptions and then remove all tasks?

    async def _remove_finished_transient_tasks(self) -> None:
        while True:
            await asyncio.sleep(1)
            finished_tasks = [x for x in self.transient_tasks if x.done()]
            if not finished_tasks:
                continue
            results = await asyncio.gather(*finished_tasks, return_exceptions=True)
            for i, exception in [
                x for x in enumerate(results) if isinstance(x[1], Exception)
                    raise exception
                except Exception:  # pylint: disable=broad-except
                    _LOG.exception("Exception in task: %r:", task)
==> Your fix will remove all tasks after the exceptions
            for task in finished_tasks:
                self.transient_tasks.remove(task)
<==

Am I right?

[gmsoft-tuxicoman]

self.transient_tasks.remove(task) only remove the reference to the tasks from the transient_tasks list. Eventually the finished tasks are still referenced in the finished_tasks list so the exception part will still work since it doesn't reference self.transient_tasks.