[root@centos3 shim-sigchld]# uname -a
Linux centos3 3.10.0-957.21.3.el7.x86_64 #1 SMP Tue Jun 18 16:35:19 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

@@ -41,12 +41,13 @@ type subscriber struct {

 func (s *subscriber) close() {
        s.Lock()
+       defer s.Unlock()
+
        if s.closed {
                return
        }
        close(s.c)
        s.closed = true
-       s.Unlock()
 }

 func (s *subscriber) do(fn func()) {
@@ -128,13 +129,14 @@ func (m *Monitor) Subscribe() chan runc.Exit {

 func (s *subscriber) do(fn func()) {
@@ -128,13 +129,14 @@ func (m *Monitor) Subscribe() chan runc.Exit {
 // Unsubscribe to process exit changes
 func (m *Monitor) Unsubscribe(c chan runc.Exit) {
        m.Lock()
+       defer m.Unlock()
+
        s, ok := m.subscribers[c]
        if !ok {
                return
        }
        s.close()
        delete(m.subscribers, c)
-       m.Unlock()
 }

 func (m *Monitor) getSubscribers() map[chan runc.Exit]*subscriber {
@@ -148,18 +150,18 @@ func (m *Monitor) getSubscribers() map[chan runc.Exit]*subscriber {
 }

 func (m *Monitor) notify(e runc.Exit) chan struct{} {
-       const timeout = 10 * time.Millisecond
        // make sure reaper can get exit events as soon as possible,  10ms is long
+       const timeout = time.Millisecond
        var (
                done    = make(chan struct{}, 1)
                timer   = time.NewTimer(timeout)
                success = make(map[chan runc.Exit]struct{})
        )
-       stop(timer)
+       stop(timer, true)

        go func() {
                defer close(done)

               // with consumers, it is not a dead cycle,if a value is specified, there is theoretically a risk of failure.
-               for i := 0; i < 100; i++ {
+               for ;; {
                        var (
                                failed      int
                                subscribers = m.getSubscribers()
@@ -173,27 +175,29 @@ func (m *Monitor) notify(e runc.Exit) chan struct{} {
                                                return
                                        }
                                        timer.Reset(timeout)
+
+                                       needRcv := true
                                        select {
+
+                                       needRcv := true
                                        select {
                                        case s.c <- e:
                                                success[s.c] = struct{}{}
                                        case <-timer.C:
+                                               needRcv = false
                                                failed++
                                        }
                                        // avoid call <-timer.C twice
-                                       stop(timer)
+                                       stop(timer, needRcv)
                                })
                        }
                        // all subscribers received the message
                        if failed == 0 {
                                return
                        }
                        // make sure reaper can get exit events as soon as possible, 100ms is too long
-                       time.Sleep(100 * time.Millisecond)
                }
        }()
        return done
 }
-func stop(timer *time.Timer) {
-       if !timer.Stop() {
+func stop(timer *time.Timer, needRcv bool) {
+       if !timer.Stop() && needRcv {
                <-timer.C
        }
 }

const bufferSize = 2048