doc/go1.20: remove mention of arena goexperiment

The arena goexperiment contains code used inside Google in very
limited use cases that we will maintain, but the discussion on #51317
identified serious problems with the very idea of adding arenas to the
standard library. In particular the concept tends to infect many other
APIs in the name of efficiency, a bit like sync.Pool except more
publicly visible.

It is unclear when, if ever, we will pick up the idea and try to push
it forward into a public API, but it's not going to happen any time
soon, and we don't want users to start depending on it: it's a true
experiment and may be changed or deleted without warning.

The arena text in the release notes makes them seem more official
and supported than they really are, and we've already seen a couple
blog posts based on that erroneous belief. Delete the text to try to
set expectations better.

Change-Id: I4f6e328ac470a9cd410f5f722d0769ef62d5e5ba
Reviewed-on: https://go-review.googlesource.com/c/go/+/462355
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Eli Bendersky <eliben@google.com>

diff --git a/doc/go1.20.html b/doc/go1.20.html
index a497f87712a4a84999e53a1262d8a851a3bd8e50..6c007fe1ffc79216bd08ce1d03168878c6f2e5c2 100644 (file)
--- a/doc/go1.20.html
+++ b/doc/go1.20.html
@@ -289,17 +289,6 @@ Do not send CLs removing the interior tags from such phrases.
 
 <h2 id="runtime">Runtime</h2>
 
-<p><!-- CL 423359, https://go.dev/issue/51317 -->
-  The runtime now has experimental support for memory-safe arena allocation
-  that makes it possible to eagerly free memory in bulk.
-  When used appropriately, it has the potential to improve CPU performance by
-  up to 15% in memory-allocation-heavy applications.
-  To try it out, build your Go program with <code>GOEXPERIMENT=arenas</code>,
-  which will make the <code>arena</code> package visible to your program.
-  Source files that import the <code>arena</code> package must require the
-  <code>goexperiment.arenas</code> build tag.
-</p>
-
 <p><!-- CL 422634 -->
   Some of the garbage collector's internal data structures were reorganized to
   be both more space and CPU efficient.
@@ -1240,3 +1229,4 @@ proxyHandler := &httputil.ReverseProxy{
 <!-- CL 453616 fix deprecation comment in archive/zip -->
 <!-- CL 453617 fix deprecation comment in encoding/csv -->
 <!-- https://go.dev/issue/54661 x/tools/go/analysis -->
+<!-- CL 423359, https://go.dev/issue/51317 arena -->