This adds a new pool type that allows byte slices
to be re-used across clients. A sync.Pool can't be used in some
cases because the the slices not in use end up getting garbage
collected due to frequent GCs.
A slower disk can can cause excessive allocations to occur when
writing to the WAL because the slower encoding and compression occurs
before taking the write lock. The encoding/compression grabs a large
byte slice from a pool and ultimately waits until it can acquire the
write lock.
This adds a throttle to limit how many inflight WAL writes can be queued
up to prevent OOMing the processess with slower disks and heavy writes.
Jason Wilder
aviau
Ben Johnson
Jonathan A. Sternberg
Philip O'Toole
Steffen Windoffer
David Howden
Cory LaNou