Bug Report: Panic in Rollback of a transaction after MySQL crash

[GuptaManan100]

Overview of the Issue

Vttablet runs into a panic while running Rollback on a transaction after MySQL crashes. Because the go-routine panics, we don't call endRequest and this causes the request to wait in CheckMySQL to block.

The panic looks like this -

E1128 15:11:07.099516       1 tabletserver.go:1361] Uncaught panic for Sql: "rollback", BindVars: {}:
startEphemeralPacketWithHeader cannot be used while a packet is already started.
vitess.io/vitess/go/mysql/conn.go:637 (0xde7fbc)
vitess.io/vitess/go/mysql/query.go:45 (0xdfea99)
vitess.io/vitess/go/mysql/query.go:320 (0xe01373)
vitess.io/vitess/go/mysql/query.go:303 (0x1202d08)
vitess.io/vitess/go/vt/dbconnpool/connection.go:47 (0x1202cfe)
vitess.io/vitess/go/vt/vttablet/tabletserver/connpool/dbconn.go:160 (0x134a804)
vitess.io/vitess/go/vt/vttablet/tabletserver/connpool/dbconn.go:188 (0x1483824)
vitess.io/vitess/go/vt/vttablet/tabletserver/stateful_connection.go:98 (0x1483816)
vitess.io/vitess/go/vt/vttablet/tabletserver/tx_pool.go:222 (0x14a5844)
...

Reproduction Steps

1. Setup a cluster
2. Run transactions via vtgate
3. Stop MySQL
4. Repeat until the panic is observed. This is inherently a timing issue and doesn't repeat easily

Binary Version

main and all previous versions

Operating System and Environment details

all

Log Fragments

No response