database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-29 05:21:33 +03:00
Code Activity

MDEV-21953 deadlock between BACKUP STAGE BLOCK_COMMIT and parallel repl.

Browse Source 
The issue was:
T1, a parallel slave worker thread, is waiting for another worker thread to
commit. While waiting, it has the MDL_BACKUP_COMMIT lock.
T2, working for mariabackup, is doing BACKUP STAGE BLOCK_COMMIT and blocks
all commits.
This causes a deadlock as the thread T1 is waiting for can't commit.

Fixed by moving locking of MDL_BACKUP_COMMIT from ha_commit_trans() to
commit_one_phase_2()

Other things:
- Added a new argument to ha_comit_one_phase() to signal if the
  transaction was a write transaction.
- Ensured that ha_maria::implicit_commit() is always called under
  MDL_BACKUP_COMMIT. This code is not needed in 10.5
- Ensure that MDL_Request values 'type' and 'ticket' are always
  initialized. This makes it easier to check the state of the MDL_Request.
- Moved thd->store_globals() earlier in handle_rpl_parallel_thread() as
  thd->init_for_queries() could use a MDL that could crash if store_globals
  where not called.
- Don't call ha_enable_transactions() in THD::init_for_queries() as this
  is both slow (uses MDL locks) and not needed.
This commit is contained in:
Monty
2020-07-20 15:19:25 +03:00
parent c4d5b6b157
commit fc48c8ff4c
11 changed files with 210 additions and 59 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
sql/handler.h
View File

@ -5021,7 +5021,7 @@ int ha_change_key_cache(KEY_CACHE *old_key_cache, KEY_CACHE *new_key_cache);
/* transactions: interface to handlerton functions */
int ha_start_consistent_snapshot(THD *thd);
int ha_commit_or_rollback_by_xid(XID *xid, bool commit);
int ha_commit_one_phase(THD *thd, bool all);
int ha_commit_one_phase(THD *thd, bool all, bool rw_trans);
int ha_commit_trans(THD *thd, bool all);
int ha_rollback_trans(THD *thd, bool all);
int ha_prepare(THD *thd);
@ -5093,4 +5093,10 @@ int del_global_table_stat(THD *thd, const LEX_CSTRING *db, const LEX_CSTRING *t
@note This does not need to be multi-byte safe or anything */
char *xid_to_str(char *buf, const XID &xid);
#endif // !DBUG_OFF
#if defined(WITH_ARIA_STORAGE_ENGINE) && MYSQL_VERSION_ID < 100500
extern void ha_maria_implicit_commit(THD *thd, bool new_trans);
#else
#define ha_maria_implicit_commit(A, B) while(0)
#endif
#endif /* HANDLER_INCLUDED */