The 1.9 release allows for the inclusion of transparent monotonic time support and better supports test helper functions. It adds parallel compilation of functions within a package and a new bit manipulation package. On top of all that, 1.9 has a novel concurrent map type. Go 1.9 also compiles functions within a package in a concurrent fashion in order to improve the speed of the Go compiler. The Go compiler now lets you compile the functions of a package in parallel so you make the most of multiple cores.
On top of that, there is the existing support for parallel compilation of totally separate packages too. Golang 1.9 also integrates a great number more improvement, additions, and fixes. The Golang 1.9 release introduces a large number of changes to the runtime, standard library, language, and tooling. Some of the most significant changes will be discussed here. The majority of the engineering that went into this release contributed to improved runtime and tooling. That might make this release seem a little less dynamic, but it includes some important and useful changes.