Reap zombie processes

services/kubelet.go

@@ -38,7 +38,7 @@ import (
 
 var kubeKubelet = &Unit{
 	Name:         "kubelet",
-	Dependencies: []*Unit{masterDiscovery, containerdGRPC, containerdTTRPC, pkiCA, pkiNode, kubeLogger},
+	Dependencies: []*Unit{masterDiscovery, containerdGRPC, containerdTTRPC, pkiCA, pkiNode, kubeLogger, reaper},
 	Run: func(u *Unit, c *Cluster, ctx context.Context) error {
 		// Sleep before starting, to make sure that containerd is actually ready
 		// (very difficult to check otherwise)

services/reaper.go

+package services
+
+import (
+	"context"
+	"os"
+	"os/signal"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+var reaper = &Unit{
+	Name: "reaper",
+	Run: func(u *Unit, c *Cluster, ctx context.Context) error {
+		sigs := make(chan os.Signal, 1)
+		signal.Notify(sigs, unix.SIGCHLD)
+		u.Markready()
+		for {
+			<-sigs
+			// Sleep before reaping, to avoid racing with native waitpid
+			// any delay will do, since we merely try to avoid accumulating defuncts
+			time.Sleep(60 * time.Second)
+			for {
+				var status unix.WaitStatus
+				_, err := unix.Wait4(-1, &status, unix.WNOHANG, nil)
+				if err != nil {
+					break
+				}
+			}
+
+		}
+	},
+}