[jpsim]

(JP from Realm here)

Realm's transactions are entirely ACID, and all transactions are thread safe. This means you can't get "faults" like you would in Core Data if one thread deletes an object being accessed in another.

On the flip side of this, it makes it difficult to share mutable object graphs across threads, mostly because then you'd need to know which Realm and which object is at what version of the db. Realm's underlying db engine supports this, but it's difficult to expose/enforce at the API level.

We have some designs in mind to allow scoping around passing objects between threads (see #3136[0]), and some other ideas for passing immutable Realms across threads, so you can expect to see some improvements there in the future.

About improving our documentation around threading, we're always open to feedback. I'd appreciate if you could read through the "Threading" section of our docs[1] and share how you think it could be improved.

[0]: https://github.com/realm/realm-cocoa/issues/3136 [1]: https://realm.io/docs/swift/latest#threading