Retry CGroup detection using pid

main.go

@@ -15,6 +15,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/filters"
@@ -99,10 +100,17 @@ func listenForMounts() {
 				panic(err)
 			} else {
 				pid := info.State.Pid
-				version, err := cgroup.GetDeviceCGroupVersion("/", pid)
-
+				var version int
+				var err error
+				for i := 0; i < 20; i++ {
+					version, err = cgroup.GetDeviceCGroupVersion("/", pid)
+					if err == nil {
+						break
+					} else {
+						time.Sleep(200 * time.Millisecond)
+					}
+				}
 				log.Printf("The cgroup version for process %d is: %v\n", pid, version)
-
 				if err != nil {
 					log.Println(err)
 					break