Internal context leak in client connection

[carzil]

What version of gRPC are you using?

v1.46.0

What version of Go are you using (go version)?

go version go1.17 darwin/amd64

What operating system (Linux, Windows, …) and version?

MacOS

What did you do?

Run following code:

package main

import (
	"context"
	"log"
	"net/http"
	_ "net/http/pprof"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/backoff"
	"google.golang.org/grpc/reflection/grpc_reflection_v1alpha"
)

func main() {
	go func() {
		if err := http.ListenAndServe("127.0.0.1:9090", nil); err != nil {
			log.Fatalf("http err: %s", err)
		}
	}()

	del := 500 * time.Microsecond

	// Connection to this address should cause some error (connection refused, i/o timeout, etc)
	conn, err := grpc.Dial("127.0.0.1:12131", grpc.WithInsecure(), grpc.WithConnectParams(
		grpc.ConnectParams{
			Backoff: backoff.Config{
				BaseDelay:  del,
				Multiplier: 1,
				Jitter:     0,
				MaxDelay:   del,
			},
		},
	))
	if err != nil {
		log.Fatalf("err: %s", err)
	}

	c := grpc_reflection_v1alpha.NewServerReflectionClient(conn)

	for {
		_, _ = c.ServerReflectionInfo(context.Background())
		time.Sleep(del)
	}
}

What did you expect to see?

I did expect that this code doesn't cause memory leak.

What did you see instead?

This code leaks. Also, del could be decreased: this code will receive i/o timeout instead of connection refused, but will leak faster.
Heap profile:

I've found that:

1. hctx is allocated here.
2. Corresponding cancel function hcancel is called in onClose.
3. But onClose is not called, if newHTTP2Client fails before transport is created (here, for example).