AsyncIOEventEmitter should keep a reference to scheduled futures

[ofacklam]

The documentation for asyncio.ensure_future indicates:

Important See also the create_task() function which is the preferred way for creating new Tasks.
Save a reference to the result of this function, to avoid a task disappearing mid-execution.

Currently, this doesn't seem to be the case in AsyncIOEventEmitter, which to my understanding only adds a "done" callback, but doesn't keep the future's reference any longer.

[jfhbrook]

I think that assigning to fut and having callback close around it might be enough. I really don't want to get in the business of storing futures in a set and tests are consistently behaving so I'm going to hold off on anything more obvious, but if there ends up being a concrete bug I'm happy to take a closer look.

[auxsvr]

When _emit_run finishes, fut is out of scope, so the future may be garbage-collected. This causes a bug in playwright that loses events, as the corresponding futures vanish before they're fully executed and the corresponding error message appears when the program finishes. A solution is to store the futures in a file-level variable, then use the callback to remove them once finished.

[hidaris]

Is there any further conclusion here?

[jfhbrook]

I'm currently pushing a fix in v9.1.1 - give it a shot, and if you still have issues let me know.

[elacuesta]

For the record, we're still observing this issue with pyee==11.0.0 (see scrapy-plugins/scrapy-playwright#188 & scrapy-plugins/scrapy-playwright#233).
I'm mostly leaving this message to keep track of this, at the time I'm not able to provide a reproducible example using only pyee and I'm well aware that the issues I mentioned add two layers of dependencies 😞.