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MDEV-16664: Change the default to innodb_lock_schedule_algorithm=fcfs

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The parameter innodb_lock_schedule_algorithm was introduced in
MariaDB Server 10.1.19, 10.2.13, 10.3.4 as part of MDEV-11039.
In MariaDB 10.1, the default value of the parameter is 'fcfs',
that is, the existing algorithm is used by default. But in
later versions of MariaDB Server, the parameter was 'vats',
enabling the new algorithm.

Because the new algorithm is triggering a debug assertion failure
that suggests corruption of the transactional lock data structures,
we will revert to the old algorithm by default until we have
resolved the problem.
This commit is contained in:
Marko Mäkelä 2018-07-07 11:34:26 +03:00
parent 8b0d4cff07
commit 1cc1d0429d
2 changed files with 3 additions and 3 deletions
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4
mysql-test/suite/sys_vars/r/sysvars_innodb.result
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@ -1604,9 +1604,9 @@ READ_ONLY YES
COMMAND_LINE_ARGUMENT NONE
VARIABLE_NAME INNODB_LOCK_SCHEDULE_ALGORITHM
SESSION_VALUE NULL
GLOBAL_VALUE vats
GLOBAL_VALUE fcfs
GLOBAL_VALUE_ORIGIN COMPILE-TIME
DEFAULT_VALUE vats
DEFAULT_VALUE fcfs
VARIABLE_SCOPE GLOBAL
VARIABLE_TYPE ENUM
VARIABLE_COMMENT The algorithm Innodb uses for deciding which locks to grant next when a lock is released. Possible values are FCFS grant the locks in First-Come-First-Served order; VATS use the Variance-Aware-Transaction-Scheduling algorithm, which uses an Eldest-Transaction-First heuristic.

2
storage/innobase/handler/ha_innodb.cc
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@ -20424,7 +20424,7 @@ static MYSQL_SYSVAR_ENUM(lock_schedule_algorithm, innodb_lock_schedule_algorithm
" VATS"
" use the Variance-Aware-Transaction-Scheduling algorithm, which"
" uses an Eldest-Transaction-First heuristic.",
NULL, NULL, INNODB_LOCK_SCHEDULE_ALGORITHM_VATS,
NULL, NULL, INNODB_LOCK_SCHEDULE_ALGORITHM_FCFS,
&innodb_lock_schedule_algorithm_typelib);
static MYSQL_SYSVAR_ULONG(buffer_pool_instances, srv_buf_pool_instances,