Mechanism 4: Shared State

Use 2-phase commit to ensure consistency and atomicity of updates.

Cluster Hash Table (CHT):

• atomic put operation, which implements swap function. Can be used to implement synchronization primitives (like test-and-set instruction)

• build apply operation, which allows a function to be applied at each replica node.

• weak apply does not ensure updates applied in same order at all nodes (but better performance).

• potential of livelock.