Thanks for looking at the patch Nick Dimiduk.
don't see why it's limited to HFileV3. Can it be made a general feature
I put the preload logic into the v3 reader because v3 is 'experimental'. Could trivially go into the v2 reader instead.
I think it could be smart about loading the blocks, load either sequentially or over a random distribution until the cache is full
Files to be preloaded are queued and scheduled to be handled by a small threadpool. When a thread picks up work for a file, the blocks are loaded sequentially using a non-pread scanner from offset 0 to the end of the index.
By random did you mean randomly select work from the file queue?
The "until full" part seems tricky as eviction detection isn't very straight-forward
Right. If we had it, I could make use of it.