spanner: If panic occurs in ReadWriteTransaction, the session will leak

[8398a7]

Client

Spanner

Environment

macOS Catalina

Go Environment

$ go version

go version go1.15.6 darwin/amd64

$ go env

Code

e.g.

package main

import (
	"context"
	"fmt"
	"log"

	"cloud.google.com/go/spanner"
)

const db = "projects/your-project/instances/your-instance/databases/your-db"

func main() {
	ctx := context.Background()
	client, _ := spanner.NewClientWithConfig(ctx, db, spanner.ClientConfig{
		SessionPoolConfig: spanner.SessionPoolConfig{MaxOpened: 5},
	})

	for i := 0; i < 5; i++ {
		func() {
			defer func() { recover() }()

			_, err := client.ReadWriteTransaction(ctx, func(ctx context.Context, tx *spanner.ReadWriteTransaction) error {
				panic("test")
				return nil
			})
			if err != nil {
				log.Println(err)
			}
		}()
		fmt.Println(i)
	}

	log.Println("start")
	_, err := client.ReadWriteTransaction(ctx, func(ctx context.Context, tx *spanner.ReadWriteTransaction) error {
		return nil
	})
	log.Println("end")
	if err != nil {
		log.Println(err)
	}
}

Expected behavior

When a panic occurs in ReadWriteTransaction, the session will leak.
I want to solve this problem.

I think that I need to rebuild the client to recover from the leaked session, but this is difficult to take care of.

Actual behavior

This is the output result. The last result is not returned.

0
1
2
3
4
2020/12/14 21:54:28 start

If you set the loop count to 4, it will return.

0
1
2
3
2020/12/14 21:55:46 start
2020/12/14 21:55:46 end

Additional context

I have a proposed fix for the problem and will create a pull request.

go.mod

module spanner-session-leak

go 1.15

require cloud.google.com/go/spanner v1.12.0