Feature description:
Testing whether background-thread access to all parts of a memory-mapped disk file of metrics will reduce or eliminate I/O when accessed on the main thread.

Eng owner: bcwhite
Product owner: asvitkine

Design doc: n/a

Are you planning on experimenting before launch? yes
Any new strings? no
Any implications for Google webservices (i.e. sync, translate)? no
Binary size? negligible
Do the existing perf tests exercise all aspects of your new feature(s)? no