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Fix for bug#14188793 - "DEADLOCK CAUSED BY ALTER TABLE DOEN'T CLEAR

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STATUS OF ROLLBACKED TRANSACTION" and bug #17054007 - "TRANSACTION
IS NOT FULLY ROLLED BACK IN CASE OF INNODB DEADLOCK".

The problem in the first bug report was that although deadlock involving
metadata locks was reported using the same error code and message as InnoDB
deadlock it didn't rollback transaction like the latter. This caused
confusion to users as in some cases after ER_LOCK_DEADLOCK transaction
could have been restarted immediately and in some cases rollback was
required.

The problem in the second bug report was that although InnoDB deadlock
caused transaction rollback in all storage engines it didn't cause release
of metadata locks. So concurrent DDL on the tables used in transaction was
blocked until implicit or explicit COMMIT or ROLLBACK was issued in the
connection which got InnoDB deadlock.

The former issue has stemmed from the fact that when support for detection
and reporting metadata locks deadlocks was added we erroneously assumed
that InnoDB doesn't rollback transaction on deadlock but only last statement
(while this is what happens on InnoDB lock timeout actually) and so didn't
implement rollback of transactions on MDL deadlocks.

The latter issue was caused by the fact that rollback of transaction due
to deadlock is carried out by setting THD::transaction_rollback_request
flag at the point where deadlock is detected and performing rollback
inside of trans_rollback_stmt() call when this flag is set. And
trans_rollback_stmt() is not aware of MDL locks, so no MDL locks are
released.

This patch solves these two problems in the following way:

- In case when MDL deadlock is detect transaction rollback is requested
  by setting THD::transaction_rollback_request flag.

- Code performing rollback of transaction if THD::transaction_rollback_request
  is moved out from trans_rollback_stmt(). Now we handle rollback request
  on the same level as we call trans_rollback_stmt() and release statement/
  transaction MDL locks.
This commit is contained in:
Dmitry Lenev
2013-08-20 13:12:34 +04:00
parent c250dbf385
commit fc2c669297
21 changed files with 257 additions and 142 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
sql/sql_parse.cc
View File

@ -1,4 +1,4 @@
/* Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@ -1183,6 +1183,18 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
close_thread_tables(thd);
thd->mdl_context.rollback_to_savepoint(mdl_savepoint);
if (thd->transaction_rollback_request)
{
/*
Transaction rollback was requested since MDL deadlock was
discovered while trying to open tables. Rollback transaction
in all storage engines including binary log and release all
locks.
*/
trans_rollback_implicit(thd);
thd->mdl_context.release_transactional_locks();
}
thd->cleanup_after_query();
break;
}
@ -1833,7 +1845,7 @@ err:
can free its locks if LOCK TABLES locked some tables before finding
that it can't lock a table in its list
*/
trans_commit_implicit(thd);
trans_rollback(thd);
/* Close tables and release metadata locks. */
close_thread_tables(thd);
DBUG_ASSERT(!thd->locked_tables_mode);
@ -1884,6 +1896,13 @@ mysql_execute_command(THD *thd)
#endif
DBUG_ASSERT(thd->transaction.stmt.is_empty() || thd->in_sub_stmt);
/*
Each statement or replication event which might produce deadlock
should handle transaction rollback on its own. So by the start of
the next statement transaction rollback request should be fulfilled
already.
*/
DBUG_ASSERT(! thd->transaction_rollback_request || thd->in_sub_stmt);
/*
In many cases first table of main SELECT_LEX have special meaning =>
check that it is first table in global list and relink it first in
@ -2070,8 +2089,8 @@ mysql_execute_command(THD *thd)
or triggers as all such statements prohibited there.
*/
DBUG_ASSERT(! thd->in_sub_stmt);
/* Commit or rollback the statement transaction. */
thd->is_error() ? trans_rollback_stmt(thd) : trans_commit_stmt(thd);
/* Statement transaction still should not be started. */
DBUG_ASSERT(thd->transaction.stmt.is_empty());
/* Commit the normal transaction if one is active. */
if (trans_commit_implicit(thd))
goto error;
@ -4503,7 +4522,17 @@ finish:
DEBUG_SYNC(thd, "execute_command_after_close_tables");
#endif
if (stmt_causes_implicit_commit(thd, CF_IMPLICIT_COMMIT_END))
if (! thd->in_sub_stmt && thd->transaction_rollback_request)
{
/*
We are not in sub-statement and transaction rollback was requested by
one of storage engines (e.g. due to deadlock). Rollback transaction in
all storage engines including binary log.
*/
trans_rollback_implicit(thd);
thd->mdl_context.release_transactional_locks();
}
else if (stmt_causes_implicit_commit(thd, CF_IMPLICIT_COMMIT_END))
{
/* No transaction control allowed in sub-statements. */
DBUG_ASSERT(! thd->in_sub_stmt);