Realm-java: "Realm instance has been closed" exception on un-closed Realm

[bmeike]

@cmelchior and @zhuinden recall quirky experiences with RealmCache causing an open Realm to appear closed.

The issue arose, recently in #4641

This issue tracks identifying and fixing the bug

[bmeike]

@zaki50 suggests that this may be related to #4551

[zaki50]

@bmeike No, since #4551 is only in the master branch and not yet released.
Sorry for confusing.

[Zhuinden]

I wanted to find this odd behavior a while ago to pinpoint it if there truly is an issue somewhere - all I know is that Realm instance doesn't "auto-close" unless you actually call close() on a Realm instance somewhere. But I don't know if calling close() on one instance can truly affect other instance.

I've been using a single UI-thread Realm instance since, but that's not really a solution :stuck_out_tongue:

[cmelchior]

Note, I don't think it is related to the RealmCache, but to the activity lifecycle. If I remember correctly last I checked, it appeared that sometimes things like ListView/RecyclerView would get invalidated during onDestroy() which would force a redraw and then naturally crash since the Realm was closed and data not available. I did not get to the bottom of it though.

[bmeike]

@cmelchior Shall I move this issue to #adapters?

[xiaogu-space]

I also encountered the same problem，is there a good solution？

[beeender]

@bmeike do we have any reproduce steps for this? After checking the original issue, it looks very much something wrong in the user's code with controlling Realm life-cycles.

[Zhuinden]

I think it was all caused by just that RealmResults and its Change listener is not invalidated / removed when activity.onDestroy is called so if a change happens after activity dies, the RealmResults is not guaranteed to be dead and can still try to update adapter even though it is a dead view hierarchy

[Zhuinden]

Also Realm should be closed only after super.onDestroy because of some accessibility magic

[Zhuinden]

@beeender so it is as if even though local instance is closed, then RealmResults is invalid even if global instance is open.

[beeender]

should be a user issue, don't see there is an issue with RealmCache. close it.