fixup 21e1d7217d60407d7de74a21bc6d0f9f1b19424e: Better workaround

1 files changed, 24 insertions, 2 deletions

diff --git a/storage/innobase/lock/lock0lock.cc b/storage/innobase/lock/lock0lock.cc
index 660a8421187..6fb21740655 100644
--- a/storage/innobase/lock/lock0lock.cc
+++ b/storage/innobase/lock/lock0lock.cc
@@ -5469,14 +5469,36 @@ void lock_sys_t::cancel(trx_t *trx, lock_t *lock)
 /** Cancel a waiting lock request (if any) when killing a transaction */
 void lock_sys_t::cancel(trx_t *trx)
 {
-  lock_sys.wr_lock(SRW_LOCK_CALL);
+#if 1 /* Work around MDEV-25016 (FIXME: remove this!) */
+  /* Parallel replication tests would occasionally hang if we did not
+  acquire exclusive lock_sys.latch here. This is not a real fix, but a
+  work-around!
+
+  It would be nice if thd_need_wait_reports() did not hold when no
+  parallel replication is in use, and only the binlog is enabled. */
+
+  if (innodb_deadlock_detect && thd_need_wait_reports(trx->mysql_thd))
+  {
+    lock_sys.wr_lock(SRW_LOCK_CALL);
+    mysql_mutex_lock(&lock_sys.wait_mutex);
+    if (lock_t *lock= trx->lock.wait_lock)
+    {
+      trx->error_state= DB_INTERRUPTED;
+      cancel(trx, lock);
+    }
+    lock_sys.wr_unlock();
+    goto func_exit;
+  }
+#endif
+  lock_sys.rd_lock(SRW_LOCK_CALL);
   mysql_mutex_lock(&lock_sys.wait_mutex);
   if (lock_t *lock= trx->lock.wait_lock)
   {
     trx->error_state= DB_INTERRUPTED;
     cancel(trx, lock);
   }
-  lock_sys.wr_unlock();
+  lock_sys.rd_unlock();
+func_exit:
   lock_sys.deadlock_check();
   mysql_mutex_unlock(&lock_sys.wait_mutex);
 }