reproduce goroutine leak in bigtable/client+grpc

main.go

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"runtime"
	"time"

	"golang.org/x/net/context"
	"golang.org/x/oauth2/google"
	"google.golang.org/cloud"
	"google.golang.org/cloud/bigtable"
)

func main() {
	if len(os.Args) == 1 {
		fmt.Println("Usage: go run main.go project zone cluster path-to-json-key table row")
		os.Exit(1)
	}

	project := os.Args[1]
	zone := os.Args[2]
	cluster := os.Args[3]
	key := os.Args[4]
	table := os.Args[5]
	row := os.Args[6]

	jsonKey, _ := ioutil.ReadFile(key)
	config, _ := google.JWTConfigFromJSON(jsonKey, bigtable.Scope) // or bigtable.AdminScope, etc.
	ctx := context.Background()
	client, _ := bigtable.NewClient(ctx, project, zone, cluster, cloud.WithTokenSource(config.TokenSource(ctx)))
	for _ = range time.Tick(1 * time.Second) {
		tbl := client.Open(table)
		r, err := tbl.ReadRow(context.Background(), row)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf("row %q: %v, goroutines: %v\n", row, r, runtime.NumGoroutine())
	}
}