Merge pull request #83373 from liggitt/automated-cherry-pick-of-#83333-upstream-release-1.14

Automated cherry pick of #83333: Don't leak a go routine on timeout

Kubernetes-commit: b1d90868ad049c8db13d4240f21e13ce3ec550a3

pkg/server/filters/timeout.go

@@ -28,6 +28,7 @@ import (
 	"time"
 
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/apiserver/pkg/endpoints/metrics"
 	apirequest "k8s.io/apiserver/pkg/endpoints/request"
 )
@@ -92,7 +93,8 @@ func (t *timeoutHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	errCh := make(chan interface{})
+	// resultCh is used as both errCh and stopCh
+	resultCh := make(chan interface{})
 	tw := newTimeoutWriter(w)
 	go func() {
 		defer func() {
@@ -103,17 +105,34 @@ func (t *timeoutHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				buf = buf[:runtime.Stack(buf, false)]
 				err = fmt.Sprintf("%v\n%s", err, buf)
 			}
-			errCh <- err
+			resultCh <- err
 		}()
 		t.handler.ServeHTTP(tw, r)
 	}()
 	select {
-	case err := <-errCh:
+	case err := <-resultCh:
 		if err != nil {
 			panic(err)
 		}
 		return
 	case <-after:
+		defer func() {
+			// resultCh needs to have a reader, since the function doing
+			// the work needs to send to it. This is defer'd to ensure it runs
+			// ever if the post timeout work itself panics.
+			go func() {
+				res := <-resultCh
+				if res != nil {
+					switch t := res.(type) {
+					case error:
+						utilruntime.HandleError(t)
+					default:
+						utilruntime.HandleError(fmt.Errorf("%v", res))
+					}
+				}
+			}()
+		}()
+
 		postTimeoutFn()
 		tw.timeout(err)
 	}