From 6104252873adb30736f8d352ebd1a30434e5805e Mon Sep 17 00:00:00 2001
From: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Date: Sun, 31 Aug 2025 12:42:45 +0300
Subject: [PATCH 1/2] experimental: mutex protection for AppendGTIDInPlace

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
---
 go/vt/vttablet/tabletserver/schema/engine.go       | 6 ++++++
 go/vt/vttablet/tabletserver/vstreamer/vstreamer.go | 4 +++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/go/vt/vttablet/tabletserver/schema/engine.go b/go/vt/vttablet/tabletserver/schema/engine.go
index 31646744c24..5bc93b21120 100644
--- a/go/vt/vttablet/tabletserver/schema/engine.go
+++ b/go/vt/vttablet/tabletserver/schema/engine.go
@@ -413,6 +413,12 @@ func (se *Engine) ReloadAtEx(ctx context.Context, pos replication.Position, incl
 	return nil
 }
 
+func (se *Engine) MutexProtected(f func()) {
+	se.mu.Lock()
+	defer se.mu.Unlock()
+	f()
+}
+
 func populateInnoDBStats(ctx context.Context, conn *connpool.Conn) (map[string]*Table, error) {
 	innodbTableSizesQuery := conn.BaseShowInnodbTableSizes()
 	if innodbTableSizesQuery == "" {
diff --git a/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go b/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
index 9a9b2a169ad..e8424ed95a0 100644
--- a/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
+++ b/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
@@ -491,7 +491,9 @@ func (vs *vstreamer) parseEvent(ev mysql.BinlogEvent, bufferAndTransmit func(vev
 				SequenceNumber: sequenceNumber,
 			})
 		}
-		vs.pos = replication.AppendGTIDInPlace(vs.pos, gtid)
+		vs.se.MutexProtected(func() {
+			vs.pos = replication.AppendGTIDInPlace(vs.pos, gtid)
+		})
 		vs.commitParent = commitParent
 		vs.sequenceNumber = sequenceNumber
 		vs.eventGTID = gtid

From 24e2a2e824af87331e23827018b0a7f6897c1903 Mon Sep 17 00:00:00 2001
From: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Date: Sun, 31 Aug 2025 14:05:13 +0300
Subject: [PATCH 2/2] use AppendGTID

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
---
 go/vt/vttablet/tabletserver/schema/engine.go       | 6 ------
 go/vt/vttablet/tabletserver/vstreamer/vstreamer.go | 4 +---
 2 files changed, 1 insertion(+), 9 deletions(-)

diff --git a/go/vt/vttablet/tabletserver/schema/engine.go b/go/vt/vttablet/tabletserver/schema/engine.go
index 5bc93b21120..31646744c24 100644
--- a/go/vt/vttablet/tabletserver/schema/engine.go
+++ b/go/vt/vttablet/tabletserver/schema/engine.go
@@ -413,12 +413,6 @@ func (se *Engine) ReloadAtEx(ctx context.Context, pos replication.Position, incl
 	return nil
 }
 
-func (se *Engine) MutexProtected(f func()) {
-	se.mu.Lock()
-	defer se.mu.Unlock()
-	f()
-}
-
 func populateInnoDBStats(ctx context.Context, conn *connpool.Conn) (map[string]*Table, error) {
 	innodbTableSizesQuery := conn.BaseShowInnodbTableSizes()
 	if innodbTableSizesQuery == "" {
diff --git a/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go b/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
index e8424ed95a0..2602c4e4f6a 100644
--- a/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
+++ b/go/vt/vttablet/tabletserver/vstreamer/vstreamer.go
@@ -491,9 +491,7 @@ func (vs *vstreamer) parseEvent(ev mysql.BinlogEvent, bufferAndTransmit func(vev
 				SequenceNumber: sequenceNumber,
 			})
 		}
-		vs.se.MutexProtected(func() {
-			vs.pos = replication.AppendGTIDInPlace(vs.pos, gtid)
-		})
+		vs.pos = replication.AppendGTID(vs.pos, gtid)
 		vs.commitParent = commitParent
 		vs.sequenceNumber = sequenceNumber
 		vs.eventGTID = gtid