Author: baolin.hbl <baolin.hbl@alibaba-inc.com>
Date:   Fri Oct 28 09:18:46 2022 +0800

[Bugfix] [bug#107991] Clone_persist_gtid causes memory leak

Problem:
========
This is a fix for bug#107991.

Since MySQL8.0, the Clone_persist_gtid thread is responsible for saving
GTID into dd table gtid_executed periodically (every 100ms).

The Clone_persist_gtid thread requests memory from thd->mem_root during
lock_tables.

Because the thread will not be closed until shutdown, the memory will not
be freed or reused.

Solution:
=========
Clear mem_root after each flush_gtids

diff --git a/storage/innobase/clone/clone0repl.cc b/storage/innobase/clone/clone0repl.cc
index 1d22a6814f4..db3488521e7 100644
--- a/storage/innobase/clone/clone0repl.cc
+++ b/storage/innobase/clone/clone0repl.cc
@@ -607,6 +607,7 @@ void Clone_persist_gtid::periodic_write() {
     os_event_reset(m_event);
     /* Write accumulated GTIDs to disk table */
     flush_gtids(thd);
+    thd->mem_root->ClearForReuse();
   }