Get rid of patched version of Go 1.8.1

build/build-image/Dockerfile

@@ -19,7 +19,7 @@ FROM gcr.io/google_containers/kube-cross:KUBE_BUILD_IMAGE_CROSS_TAG
 RUN touch /kube-build-image
 
 # To run as non-root we sometimes need to rebuild go stdlib packages.
-RUN chmod -R a+rwx /usr/local/go/pkg ${K8S_PATCHED_GOROOT}/pkg
+RUN chmod -R a+rwx /usr/local/go/pkg
 
 # For running integration tests /var/run/kubernetes is required
 # and should be writable by user

build/build-image/cross/Dockerfile

@@ -77,22 +77,3 @@ RUN export ETCD_VERSION=v3.0.17; \
   && cd /usr/local/src/etcd \
   && curl -fsSL https://github.com/coreos/etcd/releases/download/${ETCD_VERSION}/etcd-${ETCD_VERSION}-linux-amd64.tar.gz | tar -xz \
   && ln -s ../src/etcd/etcd-${ETCD_VERSION}-linux-amd64/etcd /usr/local/bin/
-
-
-# There is a significant performance regression in Go 1.8 comparing to Go 1.7.
-# Until this is solved in Go itself, we are patching 1.8.1 version of Go to
-# reduce the impact of this regression - for more detailed discussion see:
-# https://github.com/kubernetes/kubernetes/issues/45216
-#
-# TODO: Once this issue is fixed in Go itself, we can get rid of the code below.
-ENV K8S_PATCHED_GOLANG_VERSION=1.8.1 \
-    K8S_PATCHED_GOROOT=/usr/local/go_k8s_patched
-RUN mkdir -p ${K8S_PATCHED_GOROOT} \
-  && curl -sSL https://github.com/golang/go/archive/go${K8S_PATCHED_GOLANG_VERSION}.tar.gz | tar -xz -C ${K8S_PATCHED_GOROOT} --strip-components=1
-
-COPY go_181_performance_fix.patch ${K8S_PATCHED_GOROOT}/
-RUN cd ${K8S_PATCHED_GOROOT} \
-  && patch -p1 < go_181_performance_fix.patch \
-  && cd src \
-  && GOROOT_FINAL=${K8S_PATCHED_GOROOT} GOROOT_BOOTSTRAP=/usr/local/go ./make.bash \
-  && for platform in ${KUBE_CROSSPLATFORMS}; do GOOS=${platform%/*} GOARCH=${platform##*/} GOROOT=${K8S_PATCHED_GOROOT} go install std; done

build/build-image/cross/go_181_performance_fix.patch

-diff --git a/src/net/http/h2_bundle.go b/src/net/http/h2_bundle.go
-index 4536b2ff5d..84e78534a9 100644
---- a/src/net/http/h2_bundle.go
-+++ b/src/net/http/h2_bundle.go
-@@ -3536,9 +3536,17 @@ func (sc *http2serverConn) serve() {
- 		sc.idleTimerCh = sc.idleTimer.C
- 	}
- 
--	var gracefulShutdownCh <-chan struct{}
-+	var gracefulShutdownCh chan struct{}
- 	if sc.hs != nil {
--		gracefulShutdownCh = http2h1ServerShutdownChan(sc.hs)
-+		ch := http2h1ServerShutdownChan(sc.hs)
-+		gracefulShutdownCh = make(chan struct{})
-+		go func() {
-+			select {
-+			case <-sc.doneServing:
-+			case <-ch:
-+				close(gracefulShutdownCh)
-+			}
-+		}()
- 	}
- 
- 	go sc.readFrames()

hack/lib/golang.sh

@@ -267,11 +267,6 @@ kube::golang::set_platform_envs() {
 
   # Do not set CC when building natively on a platform, only if cross-compiling from linux/amd64
   if [[ $(kube::golang::host_platform) == "linux/amd64" ]]; then
-    # We are currently using go 1.8.1, which has significant performance
-    # regression. Until this is fixed in Golang head, we are using patched
-    # version of Go that eliminates this problem.
-    export GOROOT=${K8S_PATCHED_GOROOT:-${GOROOT}}
-
     # Dynamic CGO linking for other server architectures than linux/amd64 goes here
     # If you want to include support for more server platforms than these, add arch-specific gcc names here
     case "${platform}" in