Cloned from launchpad blueprint https://blueprints.launchpad.net/swift/+spec/reduce-container-contention.

Description:

Instead of always flushing the pending update log in list_objects_iter(),  check if there is a prefix parameter, and if so, only flush if:
(a) The log file reached a size threshhold (similar to the PUT logic) or an age threshhold
(b) The log file has an entry where 'obj'=<some value with the prefix> (a flush is required for correctness)
I think this could reduce the contention/frequency of flushing (and cause less fsync())  when listings are frequent.

Specification URL (additional information):

None