In order to not block modifications to the hashmap of collection truncate markers needed for Change Collection and Pre-Image collection management under one mutex we must create a lock-free hashmap. Otherwise we risk having large contention of entries.

A read-copy-update approach is suitable here as it would let us:

• Perform CollectionTruncate marker updates without any locks
• Free us from lifetime concerns in the remover thread

This map in particular should make it so all values between map instances are shared in order to coordinate correctly between threads.