From dd54ce9e10ff6553ab946bb35ec08381865ea42b Mon Sep 17 00:00:00 2001
From: Denis Protivensky <denis.protivensky@galeracluster.com>
Date: Tue, 18 Feb 2025 16:09:44 +0300
Subject: [PATCH] MDEV-36116: Remove debug assert in TOI when executing thread
 is killed

Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>
---
 mysql-test/suite/galera/r/MDEV-36116.result | 22 +++++++++++
 mysql-test/suite/galera/t/MDEV-36116.test   | 43 +++++++++++++++++++++
 sql/wsrep_mysqld.cc                         |  3 +-
 3 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 mysql-test/suite/galera/r/MDEV-36116.result
 create mode 100644 mysql-test/suite/galera/t/MDEV-36116.test

diff --git a/mysql-test/suite/galera/r/MDEV-36116.result b/mysql-test/suite/galera/r/MDEV-36116.result
new file mode 100644
index 00000000000..11899b9c09b
--- /dev/null
+++ b/mysql-test/suite/galera/r/MDEV-36116.result
@@ -0,0 +1,22 @@
+connection node_2;
+connection node_1;
+connect con1,127.0.0.1,root,,test,$NODE_MYPORT_1;
+connection node_1;
+CALL mtr.add_suppression("CREATE TABLE isolation failure");
+SET DEBUG_SYNC = 'wsrep_kill_thd_before_enter_toi SIGNAL may_kill WAIT_FOR continue';
+CREATE TABLE t1 (a INT) ENGINE=InnoDB;
+connection con1;
+SET DEBUG_SYNC = 'now WAIT_FOR may_kill';
+SET DEBUG_SYNC = 'now SIGNAL continue';
+connection node_1;
+ERROR HY000: Lost connection to MySQL server during query
+connection node_2;
+SHOW TABLES LIKE 't1';
+Tables_in_test (t1)
+connection con1;
+SHOW TABLES LIKE 't1';
+Tables_in_test (t1)
+SET DEBUG_SYNC = 'RESET';
+disconnect con1;
+disconnect node_2;
+disconnect node_1;
diff --git a/mysql-test/suite/galera/t/MDEV-36116.test b/mysql-test/suite/galera/t/MDEV-36116.test
new file mode 100644
index 00000000000..eb166e69066
--- /dev/null
+++ b/mysql-test/suite/galera/t/MDEV-36116.test
@@ -0,0 +1,43 @@
+#
+# MDEV-36116: TOI crashes in debug assert if executing thread is killed.
+#
+
+--source include/galera_cluster.inc
+--source include/have_innodb.inc
+--source include/have_debug_sync.inc
+--source include/have_debug.inc
+
+--connect con1,127.0.0.1,root,,test,$NODE_MYPORT_1
+
+# Start TOI operation and wait for the thread to be killed.
+--connection node_1
+CALL mtr.add_suppression("CREATE TABLE isolation failure");
+
+--let $connection_id = `SELECT CONNECTION_ID()`
+SET DEBUG_SYNC = 'wsrep_kill_thd_before_enter_toi SIGNAL may_kill WAIT_FOR continue';
+--send
+  CREATE TABLE t1 (a INT) ENGINE=InnoDB;
+
+# Kill the thread and let it continue.
+--connection con1
+SET DEBUG_SYNC = 'now WAIT_FOR may_kill';
+--disable_query_log
+--eval KILL CONNECTION $connection_id
+--enable_query_log
+SET DEBUG_SYNC = 'now SIGNAL continue';
+
+--connection node_1
+--error 2013
+--reap
+
+# Verify no tables created on either nodes.
+--connection node_2
+SHOW TABLES LIKE 't1';
+
+--connection con1
+SHOW TABLES LIKE 't1';
+
+# Cleanup
+SET DEBUG_SYNC = 'RESET';
+--disconnect con1
+--source include/galera_end.inc
diff --git a/sql/wsrep_mysqld.cc b/sql/wsrep_mysqld.cc
index d6332ae947d..22d66379835 100644
--- a/sql/wsrep_mysqld.cc
+++ b/sql/wsrep_mysqld.cc
@@ -2625,12 +2625,13 @@ int wsrep_to_isolation_begin(THD *thd, const char *db_, const char *table_,
                              const wsrep::key_array *fk_tables,
                              const HA_CREATE_INFO *create_info)
 {
+  DEBUG_SYNC(thd, "wsrep_kill_thd_before_enter_toi");
   mysql_mutex_lock(&thd->LOCK_thd_kill);
   const killed_state killed = thd->killed;
   mysql_mutex_unlock(&thd->LOCK_thd_kill);
   if (killed)
   {
-    DBUG_ASSERT(FALSE);
+    /* The thread may have been killed as a result of memory pressure. */
     return -1;
   }