Fail fast:
_do now allow modification in object, within the iteration loop
Ex: HashMap gives concurrent modification exception when try to modify map within the iteration. Data structure: HashMap, Array list Suitable for Single threaded system provides strong consistency Iterator works on original object. fast processing
Fail Fast
Ex: ConcurrentHashMap does not give concurrent modification exception when try to modify map within the iteration. `Data structure: ConcurrentHashMap Suitable for multi threaded system provides weak consistency Iterator works on copy of object. slow processing