Cyclic dependency between Context and Instance

[mottosso]

from pyblish.api
context = pyblish.api.Context()
instance = context.create_instance("MyInstance")

At this point, the Context holds a reference to MyInstance as a child of itself, and MyInstance holds a reference to Context through instance.parent and instance.context.

This means that neither can ever be freed from memory, causing a linear increase in memory use per added instance.

[mottosso]

This can be solved by storing a weak reference to the Context in each instance.

• weakref

[mottosso]

I think another consequence of this is that the result dictionaries stored within the context during and after publishing would also never get garbage collected, resulting in ever-increasing memory use per reset and publish. Take a moment to think about how much data that can actually, every plug-in and log message is included there. Kilobytes per result, at least, multiplied by tens if not hundreds of results per publish.

[tokejepsen]

Guessing this is the source of the constant memory increase we have been reporting?

[mottosso]

Possibly. I've managed to plug this particular hole for now so it's likely we'll experience whether or not that's what it was. I'll be doing some proper memory hunting next.