From 801a520ec2abf8baee54f769096763398085a6d7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A1nos=20Benjamin=20Antal?=
 <benjamin.antal@clickhouse.com>
Date: Fri, 5 Dec 2025 15:49:29 +0000
Subject: [PATCH] Lock topic partition when reading leader epoch while fetching
 topic partitions

---
 src/rdkafka_fetcher.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/rdkafka_fetcher.c b/src/rdkafka_fetcher.c
index e275ee5a88..2b614f6230 100644
--- a/src/rdkafka_fetcher.c
+++ b/src/rdkafka_fetcher.c
@@ -1106,6 +1106,7 @@ int rd_kafka_broker_fetch_toppars(rd_kafka_broker_t *rkb, rd_ts_t now) {
 
                 if (rd_kafka_buf_ApiVersion(rkbuf) >= 9) {
                         /* CurrentLeaderEpoch */
+                        rd_kafka_toppar_lock(rktp);
                         if (rktp->rktp_leader_epoch < 0 &&
                             rd_kafka_has_reliable_leader_epochs(rkb)) {
                                 /* If current leader epoch is set to -1 and
@@ -1121,6 +1122,7 @@ int rd_kafka_broker_fetch_toppars(rd_kafka_broker_t *rkb, rd_ts_t now) {
                                 rd_kafka_buf_write_i32(rkbuf,
                                                        rktp->rktp_leader_epoch);
                         }
+                        rd_kafka_toppar_unlock(rktp);
                 }
                 /* FetchOffset */
                 rd_kafka_buf_write_i64(rkbuf,