From 79e9ff44d18f5fb986870cfac17fc661fb098098 Mon Sep 17 00:00:00 2001 From: Kristian Nielsen Date: Mon, 23 Feb 2015 13:37:34 +0100 Subject: [PATCH] MDEV-7458: Deadlock in parallel replication can allow following transaction to start replicating too early In parallel replication, don't rollback inside ha_commit_trans() in case of error. The rollback will be done later, but the parallel replication code needs to run unmark_start_commit() before the rollback to properly control the sequencing of transactions. I did not manage to come up with a reliable automatic test case for this, but I tested it manually. --- sql/handler.cc | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/sql/handler.cc b/sql/handler.cc index 518ca7b860d..b92db125cf5 100644 --- a/sql/handler.cc +++ b/sql/handler.cc @@ -1445,7 +1445,13 @@ done: /* Come here if error and we need to rollback. */ err: error= 1; /* Transaction was rolled back */ - ha_rollback_trans(thd, all); + /* + In parallel replication, rollback is delayed, as there is extra replication + book-keeping to be done before rolling back and allowing a conflicting + transaction to continue (MDEV-7458). + */ + if (!(thd->rgi_slave && thd->rgi_slave->is_parallel_exec)) + ha_rollback_trans(thd, all); end: if (rw_trans && mdl_request.ticket)