Add SIGUSR1 to print the stack of containerd

Signed-off-by: Lei Jitang <leijitang@huawei.com>

cmd/containerd/main.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/signal"
 	"path/filepath"
+	"runtime"
 	"time"
 
 	"github.com/boltdb/bolt"
@@ -436,3 +437,18 @@ func interceptor(ctx gocontext.Context,
 	}
 	return grpc_prometheus.UnaryServerInterceptor(ctx, req, info, handler)
 }
+
+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]
+	logrus.Infof("=== BEGIN goroutine stack dump ===\n%s\n=== END goroutine stack dump ===", buf)
+}