For anyone looking for more examples of 1BRC in Go, we had a friendly competition at work and collected the results here: https://github.com/dhartunian/1brcgo/

In addition to the loop-unrolling and bit-twiddling tricks that also show up in the fastest Java and C++ versions, some Go-specific things I learned were:

- unsafe.Pointer can be used to read memory without bounds checks

- many functions in the bytes and bits packages in the standard library are written in assembly

- debug.SetGCPercent and SetMemoryLimit to turn off GC

- runtime.LockOSThread to lock a goroutine to a thread

- print is slightly faster than fmt.Printf (but writes to stderr)