foo.diff

diff --git a/go/vt/vttablet/tabletserver/tx_pool.go b/go/vt/vttablet/tabletserver/tx_pool.go
index 872e3825e..a1080420e 100644
--- a/go/vt/vttablet/tabletserver/tx_pool.go
+++ b/go/vt/vttablet/tabletserver/tx_pool.go
@@ -426,30 +426,31 @@ func (axp *TxPool) SetPoolTimeout(timeout time.Duration) {
 // are failures.
 type TxConnection struct {
 	*connpool.DBConn
 	TransactionID     int64
 	pool              *TxPool
 	StartTime         time.Time
 	EndTime           time.Time
 	Queries           []string
 	NewMessages       map[string][]*messager.MessageRow
 	ChangedMessages   map[string][]string
 	Conclusion        string
 	LogToFile         sync2.AtomicInt32
 	ImmediateCallerID *querypb.VTGateCallerID
 	EffectiveCallerID *vtrpcpb.CallerID
 	Autocommit        bool
+	concludeMu 		  sync.Mutex
 }
 
 func newTxConnection(conn *connpool.DBConn, transactionID int64, pool *TxPool, immediate *querypb.VTGateCallerID, effective *vtrpcpb.CallerID, autocommit bool) *TxConnection {
 	return &TxConnection{
 		DBConn:            conn,
 		TransactionID:     transactionID,
 		pool:              pool,
 		StartTime:         time.Now(),
 		NewMessages:       make(map[string][]*messager.MessageRow),
 		ChangedMessages:   make(map[string][]string),
 		ImmediateCallerID: immediate,
 		EffectiveCallerID: effective,
 		Autocommit:        autocommit,
 	}
 }
@@ -487,30 +488,37 @@ func (txc *TxConnection) BeginAgain(ctx context.Context) error {
 // active.
 func (txc *TxConnection) Recycle() {
 	if txc.IsClosed() {
 		txc.conclude(TxClose, "closed")
 	} else {
 		txc.pool.activePool.Put(txc.TransactionID)
 	}
 }
 
 // RecordQuery records the query against this transaction.
 func (txc *TxConnection) RecordQuery(query string) {
 	txc.Queries = append(txc.Queries, query)
 }
 
 func (txc *TxConnection) conclude(conclusion, reason string) {
+	txc.concludeMu.Lock()
+	defer txc.concludeMu.Unlock()
+	if (txc.DBConn == nil) {
+		// Another process already concluded this connection. Bail to avoid a go panic.
+		return
+	}
+
 	txc.pool.activePool.Unregister(txc.TransactionID, reason)
 	txc.DBConn.Recycle()
 	txc.DBConn = nil
 	txc.pool.limiter.Release(txc.ImmediateCallerID, txc.EffectiveCallerID)
 	txc.log(conclusion)
 }
 
 func (txc *TxConnection) log(conclusion string) {
 	txc.Conclusion = conclusion
 	txc.EndTime = time.Now()
 
 	username := callerid.GetPrincipal(txc.EffectiveCallerID)
 	if username == "" {
 		username = callerid.GetUsername(txc.ImmediateCallerID)
 	}