The majority of parallel select works. Current problems:

There still exist subtle race conditions. Parallel chunks should be higher due to thread overhead.
We currently deal with drilling down into the last "chunk" serially (should be made log(n) parallel). More importantly, we almost always say the first is bad -- this is because of our counting approach doesn't reset. In the last chunk, they've all been touched by the parallel block, so there's a high chance that we'll erroneously pick one of the first ones.