Merge pull request #223 from crosbymichael/reap-shim

Remove sigchld reaper from containerd process

containerd/main.go

@@ -134,10 +134,7 @@ func daemon(context *cli.Context) error {
 	// setup a standard reaper so that we don't leave any zombies if we are still alive
 	// this is just good practice because we are spawning new processes
 	s := make(chan os.Signal, 2048)
-	signal.Notify(s, syscall.SIGCHLD, syscall.SIGTERM, syscall.SIGINT)
+	signal.Notify(s, syscall.SIGTERM, syscall.SIGINT)
-	if err := osutils.SetSubreaper(1); err != nil {
-		logrus.WithField("error", err).Error("containerd: set subpreaper")
-	}
 	sv, err := supervisor.New(
 		context.String("state-dir"),
 		context.String("runtime"),
@@ -169,10 +166,6 @@ func daemon(context *cli.Context) error {
 	}
 	for ss := range s {
 		switch ss {
-		case syscall.SIGCHLD:
-			if _, err := osutils.Reap(); err != nil {
-				logrus.WithField("error", err).Warn("containerd: reap child processes")
-			}
 		default:
 			logrus.Infof("stopping containerd after receiving %s", ss)
 			server.Stop()

runtime/container.go

@@ -478,6 +478,7 @@ func (c *container) Exec(pid string, pspec specs.ProcessSpec, s Stdio) (pp Proce
 }
 
 func (c *container) startCmd(pid string, cmd *exec.Cmd, p *process) error {
+	p.cmd = cmd
 	if err := cmd.Start(); err != nil {
 		if exErr, ok := err.(*exec.Error); ok {
 			if exErr.Err == exec.ErrNotFound || exErr.Err == os.ErrNotExist {
@@ -699,6 +700,9 @@ func (c *container) waitForStart(p *process, cmd *exec.Cmd) error {
 
 // isAlive checks if the shim that launched the container is still alive
 func isAlive(cmd *exec.Cmd) (bool, error) {
+	if _, err := syscall.Wait4(cmd.Process.Pid, nil, syscall.WNOHANG, nil); err == nil {
+		return true, nil
+	}
 	if err := syscall.Kill(cmd.Process.Pid, 0); err != nil {
 		if err == syscall.ESRCH {
 			return false, nil

runtime/process.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strconv"
 	"syscall"
@@ -39,6 +40,8 @@ type Process interface {
 	SystemPid() int
 	// State returns if the process is running or not
 	State() State
+	// Wait reaps the shim process if avaliable
+	Wait()
 }
 
 type processConfig struct {
@@ -139,6 +142,7 @@ type process struct {
 	container   *container
 	spec        specs.ProcessSpec
 	stdio       Stdio
+	cmd         *exec.Cmd
 }
 
 func (p *process) ID() string {
@@ -219,6 +223,13 @@ func (p *process) getPidFromFile() (int, error) {
 	return i, nil
 }
 
+// Wait will reap the shim process
+func (p *process) Wait() {
+	if p.cmd != nil {
+		p.cmd.Wait()
+	}
+}
+
 func getExitPipe(path string) (*os.File, error) {
 	if err := syscall.Mkfifo(path, 0755); err != nil && !os.IsExist(err) {
 		return nil, err

supervisor/sort_test.go

@@ -61,6 +61,10 @@ func (p *testProcess) State() runtime.State {
 	return runtime.Running
 }
 
+func (p *testProcess) Wait() {
+
+}
+
 func TestSortProcesses(t *testing.T) {
 	p := []runtime.Process{
 		&testProcess{"ls"},

supervisor/supervisor.go

@@ -274,6 +274,7 @@ func (s *Supervisor) SendTask(evt Task) {
 
 func (s *Supervisor) exitHandler() {
 	for p := range s.monitor.Exits() {
+		p.Wait()
 		e := &ExitTask{
 			Process: p,
 		}