cmd/go: enable concurrent backend compilation by default

It can be disabled by setting the environment variable
GO19CONCURRENTCOMPILATION=0, or with -gcflags=-c=1.

Fixes #15756.

Change-Id: I7acbf16330512b62ee14ecbab1f46b53ec5a67b6
Reviewed-on: https://go-review.googlesource.com/41820
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/go/internal/work/build.go b/src/cmd/go/internal/work/build.go
index 0419eb29c2f55303a05d771d7ef6b98bf66e07d4..1cd2138087bd47f4ee250bf91ba6185c68db43e4 100644 (file)
--- a/src/cmd/go/internal/work/build.go
+++ b/src/cmd/go/internal/work/build.go
@@ -144,7 +144,7 @@ See also: go install, go get, go clean.
        `,
 }
 
-const concurrentGCBackendCompilationEnabledByDefault = false
+const concurrentGCBackendCompilationEnabledByDefault = true
 
 func init() {
        // break init cycle