Add stack dump.

Signed-off-by: Lantao Liu <lantaol@google.com>

cmd/cri-containerd/cri_containerd.go

@@ -19,6 +19,9 @@ package main
 import (
 	"flag"
 	"os"
+	"os/signal"
+	"runtime"
+	"syscall"
 
 	"github.com/docker/docker/pkg/reexec"
 	"github.com/golang/glog"
@@ -83,6 +86,7 @@ func main() {
 	cmd.AddCommand(versionCommand())
 
 	cmd.Run = func(cmd *cobra.Command, args []string) {
+		setupDumpStacksTrap()
 		if err := o.InitFlags(cmd.Flags()); err != nil {
 			glog.Exitf("Failed to init CRI containerd flags: %v", err)
 		}
@@ -118,3 +122,28 @@ func validateConfig(o *options.CRIContainerdOptions) {
 		selinux.SetDisabled()
 	}
 }
+
+func setupDumpStacksTrap() {
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, syscall.SIGUSR1)
+	go func() {
+		for range c {
+			dumpStacks()
+		}
+	}()
+}
+
+func dumpStacks() {
+	var (
+		buf       []byte
+		stackSize int
+	)
+	bufferLen := 16384
+	for stackSize == len(buf) {
+		buf = make([]byte, bufferLen)
+		stackSize = runtime.Stack(buf, true)
+		bufferLen *= 2
+	}
+	buf = buf[:stackSize]
+	glog.V(0).Infof("=== BEGIN goroutine stack dump ===\n%s\n=== END goroutine stack dump ===", buf)
+}