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MDEV-9416: MariaDB galera got signal 11 when altering table add unique index

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When a BF thread attempts to abort a victim thread's transaction,
the victim thread is not locked and thus its not safe to rely on
its data structures like htons registered for the trx.

So, instead of getting the registered htons from victim, innodb's
hton can be looked up directly from installed_htons[] and used to
abort the transaction. (Same technique is used in older versions)
This commit is contained in:
Nirbhay Choubey 2016-09-28 13:27:34 -04:00
parent 7c525ce36b
commit d5dfa0f1c2
1 changed files with 15 additions and 21 deletions
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32
sql/handler.cc
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@ -6096,6 +6096,13 @@ void handler::set_lock_type(enum thr_lock_type lock)
@note Aborting the transaction does NOT end it, it still has to
be rolled back with hton->rollback().
@note It is safe to abort from one thread (bf_thd) the transaction,
running in another thread (victim_thd), because InnoDB's lock_sys and
trx_mutex guarantee the necessary protection. However, its not safe
to access victim_thd->transaction, because it's not protected from
concurrent accesses. And it's an overkill to take LOCK_plugin and
iterate the whole installed_htons[] array every time.
@param bf_thd brute force THD asking for the abort
@param victim_thd victim THD to be aborted
@ -6112,29 +6119,16 @@ int ha_abort_transaction(THD *bf_thd, THD *victim_thd, my_bool signal)
DBUG_RETURN(0);
}
/* Try statement transaction if standard one is not set. */
THD_TRANS *trans= (victim_thd->transaction.all.ha_list) ?
&victim_thd->transaction.all : &victim_thd->transaction.stmt;
Ha_trx_info *ha_info= trans->ha_list, *ha_info_next;
for (; ha_info; ha_info= ha_info_next)
{
handlerton *hton= ha_info->ht();
if (!hton->abort_transaction)
{
/* Skip warning for binlog & wsrep. */
if (hton->db_type != DB_TYPE_BINLOG && hton != wsrep_hton)
{
WSREP_WARN("Cannot abort transaction.");
}
}
else
handlerton *hton= installed_htons[DB_TYPE_INNODB];
if (hton && hton->abort_transaction)
{
hton->abort_transaction(hton, bf_thd, victim_thd, signal);
}
ha_info_next= ha_info->next();
else
{
WSREP_WARN("Cannot abort InnoDB transaction");
}
DBUG_RETURN(0);
}