As brought up under HDFS-14277, we should make sure SBN read has no performance impact when it is not enabled. One potential overhead of SBN read is maintaining and updating additional state status on NameNode. Specifically, this is done by creating/updating/checking a GlobalStateIdContext instance. Currently, even without enabling SBN read, this logic is still be checked. We can make this configurable so that when SBN read is not enabled, there is no such overhead and everything works as-is.
- is related to
HDFS-14277 [SBN read] Observer benchmark results