Wait for all exec process child before exiting from shim

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

containerd-shim/main.go

@@ -106,7 +106,7 @@ func start(log *os.File) error {
 		case s := <-signals:
 			switch s {
 			case syscall.SIGCHLD:
-				exits, _ := osutils.Reap()
+				exits, _ := osutils.Reap(false)
 				for _, e := range exits {
 					// check to see if runtime is one of the processes that has exited
 					if e.Pid == p.pid() {
@@ -117,6 +117,9 @@ func start(log *os.File) error {
 			}
 			// runtime has exited so the shim can also exit
 			if exitShim {
+				// Wait for all the childs this process may have created
+				// (only needed for exec, but it won't hurt when done on init)
+				osutils.Reap(true)
 				// Let containerd take care of calling the runtime delete
 				f.Close()
 				p.Wait()

osutils/reaper.go

@@ -12,13 +12,17 @@ type Exit struct {
 
 // Reap reaps all child processes for the calling process and returns their
 // exit information
-func Reap() (exits []Exit, err error) {
+func Reap(wait bool) (exits []Exit, err error) {
 	var (
 		ws  syscall.WaitStatus
 		rus syscall.Rusage
 	)
+	flag := syscall.WNOHANG
+	if wait {
+		flag = 0
+	}
 	for {
-		pid, err := syscall.Wait4(-1, &ws, syscall.WNOHANG, &rus)
+		pid, err := syscall.Wait4(-1, &ws, flag, &rus)
 		if err != nil {
 			if err == syscall.ECHILD {
 				return exits, nil