Once the user map has been reconstructed, it is necessary to reconstruct the soft state at user managers with new user responsibilities. Specifically, this soft state is the user profile soft state and the mailbox fragment list for each user. Essentially, every node pushes soft state corresponding to any of its hard state to new user managers responsible for that soft state.
Reconstruction is a two-step process, completely distributed, but unsynchronized.
The first step occurs immediately after membership reconfiguration. Here, each node compares the previous and current user maps to identify any buckets having fresh assignments. Recall that the user map associates nodes with hash buckets, so the relevant soft state belonging on a node is that corresponding to those users who hash into the buckets assigned to the node. Each node proceeds independently to the second step. Here, every node identifying another node's fresh bucket assignment sends it any soft state corresponding to the hard state for that bucket maintained on the sending node.