content: Go 1.9 is released

Change-Id: I386de65619857af423548316f134298dc1974da4
Reviewed-on: https://go-review.googlesource.com/58591
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 68 insertions, 0 deletions

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+Go 1.9 is released
+24 Aug 2017
+
+Francesc Campoy
+campoy@golang.org
+
+* Introduction
+
+Today the Go team is happy to announce the release of Go 1.9.
+You can get it from the [[https://golang.org/dl/][download page]].
+There are many changes to the language, standard library, runtime, and tooling.
+This post covers the most significant visible ones.
+Most of the engineering effort put into this release went to improvements of the runtime and tooling,
+which makes for a less exciting announcement, but nonetheless a great release.
+
+The most important change to the language is the introduction of type aliases: a feature
+created to support gradual code repair. A type alias declaration has the form:
+
+	type T1 = T2
+
+This declaration introduces an alias name `T1` for the type `T2`, in the same way that `byte` has
+always been an alias for `uint8`.
+The [[https://golang.org/design/18130-type-alias][type alias design document]] and
+[[https://talks.golang.org/2016/refactor.article][an article on refactoring]] cover this addition in more detail.
+
+The new [[https://golang.org/pkg/math/bits][math/bits]] package provides bit counting and manipulation functions
+for unsigned integers, implemented by special CPU instructions when possible.
+For example, on x86-64 systems, `bits.TrailingZeros(x)` uses the
+[[https://pdos.csail.mit.edu/6.828/2010/readings/i386/BSF.htm][BSF]] instruction.
+
+The `sync` package has added a new [[https://golang.org/pkg/sync#Map][Map]] type, safe for concurrent access.
+You can read more about it from its documentation and learn more about why it was created from this
+[[https://www.youtube.com/watch?v=C1EtfDnsdDs][GopherCon 2017 lightning talk]]
+([[https://github.com/gophercon/2017-talks/blob/master/lightningtalks/BryanCMills-AnOverviewOfSyncMap/An%20Overview%20of%20sync.Map.pdf][slides]]).
+It is not a general replacement for Go's map type; please see the documentation to learn when it should be used.
+
+The `testing` package also has an addition. The new `Helper` method, added to both
+[[https://golang.org/pkg/testing#T.Helper][testing.T]] and [[https://golang.org/pkg/testing#B.Helper][testing.B]],
+marks the calling function as a test helper function.
+When the testing package prints file and line information, it shows the location of the call to a helper function
+instead of a line in the helper function itself.
+
+For example, consider this test:
+
+.code go1.9/helper_test.go /package p/,
+
+Because `failure` identifies itself as a test helper, the error message printed during `Test` will indicate line 11,
+where `failure` is called, instead of line 7, where `failure` calls `t.Fatal`.
+
+The `time` package now transparently tracks monotonic time in each `Time` value,
+making computing durations between two `Time` values a safe operation in the presence of wall clock adjustments.
+For example, this code now computes the right elapsed time even across a leap second clock reset:
+
+	start := time.Now()
+	f()
+	elapsed := time.Since(start)
+
+See the [[http://beta.golang.org/pkg/time/#hdr-Monotonic_Clocks][package docs]] and
+[[https://github.com/golang/proposal/blob/master/design/12914-monotonic.md][design document]] for details.
+
+Finally, as part of the efforts to make the Go compiler faster, Go 1.9 compiles functions in a package concurrently.
+
+Go 1.9 includes many more additions, improvements, and fixes. Find the complete set of changes,
+and more information about the improvements listed above, in the
+[[https://golang.org/doc/go1.9][Go 1.9 release notes]].
+
+To celebrate the release, Go User Groups around the world are holding
+[[https://github.com/golang/cowg/blob/master/events/2017-08-go1.9-release-party.md][release parties]].
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