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Data race between mysqlConn watcher and okHandler during context cancellation #1559
Description
Issue description
I have one goroutine running database transactions in a loop and another goroutine cancels the context being used. This leads to the data race shown below.
Example code
Execute with go test -v -race . -test.count 1000 -test.failfast -test.run 'TestRace'
func TestRace(t *testing.T) {
r := require.New(t)
driver := mysql.MySQLDriver{}
connector, err := driver.OpenConnector("root:SoupOrSecret@/mysql")
r.NoError(err)
db := sql.OpenDB(connector)
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
triggerCancel := make(chan struct{})
done := make(chan struct{})
go func() {
defer close(done)
didTrigger := false
for ctx.Err() == nil {
tx, err := db.BeginTx(ctx, nil)
if errors.Is(err, context.Canceled) {
return
}
r.NoError(err)
var one int
err = tx.QueryRowContext(ctx, "SELECT 1").Scan(&one)
if errors.Is(err, context.Canceled) {
return
}
r.NoError(err)
_ = tx.Rollback()
if !didTrigger {
didTrigger = true
close(triggerCancel)
}
}
}()
<-triggerCancel
time.Sleep(10 * time.Millisecond)
cancel()
<-done
}Error log
WARNING: DATA RACE
Write at 0x00c000392458 by goroutine 28578:
github.com/go-sql-driver/mysql.(*mysqlConn).clearResult()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/packets.go:630 +0x1c4
github.com/go-sql-driver/mysql.(*mysqlConn).cleanup()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/connection.go:156 +0x1a4
github.com/go-sql-driver/mysql.(*mysqlConn).cancel()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/connection.go:441 +0x84
github.com/go-sql-driver/mysql.(*mysqlConn).startWatcher.func1()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/connection.go:628 +0x234
Previous read at 0x00c000392458 by goroutine 30352:
github.com/go-sql-driver/mysql.(*okHandler).handleOkPacket()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/packets.go:650 +0xfd
github.com/go-sql-driver/mysql.(*okHandler).readResultSetHeaderPacket()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/packets.go:536 +0x36f
github.com/go-sql-driver/mysql.(*mysqlConn).exec()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/connection.go:336 +0x18d
github.com/go-sql-driver/mysql.(*mysqlConn).begin()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/connection.go:121 +0x8a
github.com/go-sql-driver/mysql.(*mysqlConn).BeginTx()
/home/runner/go/pkg/mod/github.com/go-sql-driver/mysql@v1.8.0/connection.go:498 +0x156
database/sql.ctxDriverBegin()
/opt/hostedtoolcache/go/1.20.14/x64/src/database/sql/ctxutil.go:104 +0x105
database/sql.(*DB).beginDC.func1()
/opt/hostedtoolcache/go/1.20.14/x64/src/database/sql/sql.go:1868 +0x156
database/sql.withLock()
/opt/hostedtoolcache/go/1.20.14/x64/src/database/sql/sql.go:3405 +0xa2
database/sql.(*DB).beginDC()
/opt/hostedtoolcache/go/1.20.14/x64/src/database/sql/sql.go:1864 +0x113
database/sql.(*DB).begin()
/opt/hostedtoolcache/go/1.20.14/x64/src/database/sql/sql.go:1857 +0x104
database/sql.(*DB).BeginTx.func1()
Configuration
Driver version (or git SHA): 1.8.0
Go version: 1.20.7 & 1.22.1
Server version: mysql-v8 & mariadb-v10
Server OS: Ubuntu 22.04 (an ubuntu-latest GitHub actions runner)
Reacted by Maria Ines Parnisari and Kei Arima
Activity
miparnisari commentedon Mar 16, 2024
I am seeing something similar: https://github.com/openfga/openfga/actions/runs/8271747091/job/22632184961
fix race condition when context is canceled (#1562)
fix race condition when context is canceled (go-sql-driver#1562)
fix race condition when context is canceled (go-sql-driver#1562)
fix race condition when context is canceled (#1565)
methane commentedon Mar 17, 2024
I merged the fix to 1.8 branch.
Please try
go get -u github.com/go-sql-driver/mysql@1.8.bobvawter commentedon Mar 17, 2024
That fix is working for me. Thank you for the quick response.
update changelog for releasing v1.8.1 (#1576)
update changelog for releasing v1.8.1 (go-sql-driver#1576)