Granularity describes the size of independently mutable units in a data structure. In a concurrent simulator, an outer map can contain separately mutable values, allowing one internal value to change without updating the whole map. section 8.2.2
Compare the two designs when multiple threads update stored values:
- Coarse-grained design: use MVar (Map Key Value); replace values in the map and update the outer MVar repeatedly. section 8.2.2
- Choose finer granularity when repeated updates target individual keys and concurrency benefits from distributing control across values. section 8.2.2
