2 files changed, 21 insertions, 12 deletions

diff --git a/src/net/http/http_test.go b/src/net/http/http_test.go
index 49c2b4196a..3f1d7cee71 100644
--- a/src/net/http/http_test.go
+++ b/src/net/http/http_test.go
@@ -13,13 +13,8 @@ import (
 	"os/exec"
 	"reflect"
 	"testing"
-	"time"
 )
 
-func init() {
-	shutdownPollInterval = 5 * time.Millisecond
-}
-
 func TestForeachHeaderElement(t *testing.T) {
 	tests := []struct {
 		in   string
diff --git a/src/net/http/server.go b/src/net/http/server.go
index ba473d14f5..4776d960e5 100644
--- a/src/net/http/server.go
+++ b/src/net/http/server.go
@@ -15,6 +15,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"math/rand"
 	"net"
 	"net/textproto"
 	"net/url"
@@ -2691,14 +2692,14 @@ func (srv *Server) Close() error {
 	return err
 }
 
-// shutdownPollInterval is how often we poll for quiescence
-// during Server.Shutdown. This is lower during tests, to
-// speed up tests.
+// shutdownPollIntervalMax is the max polling interval when checking
+// quiescence during Server.Shutdown. Polling starts with a small
+// interval and backs off to the max.
 // Ideally we could find a solution that doesn't involve polling,
 // but which also doesn't have a high runtime cost (and doesn't
 // involve any contentious mutexes), but that is left as an
 // exercise for the reader.
-var shutdownPollInterval = 500 * time.Millisecond
+const shutdownPollIntervalMax = 500 * time.Millisecond
 
 // Shutdown gracefully shuts down the server without interrupting any
 // active connections. Shutdown works by first closing all open
@@ -2731,8 +2732,20 @@ func (srv *Server) Shutdown(ctx context.Context) error {
 	}
 	srv.mu.Unlock()
 
-	ticker := time.NewTicker(shutdownPollInterval)
-	defer ticker.Stop()
+	pollIntervalBase := time.Millisecond
+	nextPollInterval := func() time.Duration {
+		// Add 10% jitter.
+		interval := pollIntervalBase + time.Duration(rand.Intn(int(pollIntervalBase/10)))
+		// Double and clamp for next time.
+		pollIntervalBase *= 2
+		if pollIntervalBase > shutdownPollIntervalMax {
+			pollIntervalBase = shutdownPollIntervalMax
+		}
+		return interval
+	}
+
+	timer := time.NewTimer(nextPollInterval())
+	defer timer.Stop()
 	for {
 		if srv.closeIdleConns() && srv.numListeners() == 0 {
 			return lnerr
@@ -2740,7 +2753,8 @@ func (srv *Server) Shutdown(ctx context.Context) error {
 		select {
 		case <-ctx.Done():
 			return ctx.Err()
-		case <-ticker.C:
+		case <-timer.C:
+			timer.Reset(nextPollInterval())
 		}
 	}
 }