Since log_throttle is not available in 5.5. Logging of
error message for failure of thread to create new connection
in "create_thread_to_handle_connection" is not backported.
Since, function "my_plugin_log_message" is not available in
5.5 version and since there is incompatibility between
sql_print_XXX function compiled with g++ and alog files with
gcc to use sql_print_error, changes related to audit log
plugin is not backported.
bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ
LOCK" and bug #54673 "It takes too long to get readlock for
'FLUSH TABLES WITH READ LOCK'".
The first bug manifested itself as a deadlock which occurred
when a connection, which had some table open through HANDLER
statement, tried to update some data through DML statement
while another connection tried to execute FLUSH TABLES WITH
READ LOCK concurrently.
What happened was that FTWRL in the second connection managed
to perform first step of GRL acquisition and thus blocked all
upcoming DML. After that it started to wait for table open
through HANDLER statement to be flushed. When the first connection
tried to execute DML it has started to wait for GRL/the second
connection creating deadlock.
The second bug manifested itself as starvation of FLUSH TABLES
WITH READ LOCK statements in cases when there was a constant
stream of concurrent DML statements (in two or more
connections).
This has happened because requests for protection against GRL
which were acquired by DML statements were ignoring presence of
pending GRL and thus the latter was starved.
This patch solves both these problems by re-implementing GRL
using metadata locks.
Similar to the old implementation acquisition of GRL in new
implementation is two-step. During the first step we block
all concurrent DML and DDL statements by acquiring global S
metadata lock (each DML and DDL statement acquires global IX
lock for its duration). During the second step we block commits
by acquiring global S lock in COMMIT namespace (commit code
acquires global IX lock in this namespace).
Note that unlike in old implementation acquisition of
protection against GRL in DML and DDL is semi-automatic.
We assume that any statement which should be blocked by GRL
will either open and acquires write-lock on tables or acquires
metadata locks on objects it is going to modify. For any such
statement global IX metadata lock is automatically acquired
for its duration.
The first problem is solved because waits for GRL become
visible to deadlock detector in metadata locking subsystem
and thus deadlocks like one in the first bug become impossible.
The second problem is solved because global S locks which
are used for GRL implementation are given preference over
IX locks which are acquired by concurrent DML (and we can
switch to fair scheduling in future if needed).
Important change:
FTWRL/GRL no longer blocks DML and DDL on temporary tables.
Before this patch behavior was not consistent in this respect:
in some cases DML/DDL statements on temporary tables were
blocked while in others they were not. Since the main use cases
for FTWRL are various forms of backups and temporary tables are
not preserved during backups we have opted for consistently
allowing DML/DDL on temporary tables during FTWRL/GRL.
Important change:
This patch changes thread state names which are used when
DML/DDL of FTWRL is waiting for global read lock. It is now
either "Waiting for global read lock" or "Waiting for commit
lock" depending on the stage on which FTWRL is.
Incompatible change:
To solve deadlock in events code which was exposed by this
patch we have to replace LOCK_event_metadata mutex with
metadata locks on events. As result we have to prohibit
DDL on events under LOCK TABLES.
This patch also adds extensive test coverage for interaction
of DML/DDL and FTWRL.
Performance of new and old global read lock implementations
in sysbench tests were compared. There were no significant
difference between new and old implementations.
This assert could be triggered if ALTER EVENT failed to load the
event after altering it. Failing to load the event could for
example happen because of KILL QUERY.
The assert tested that the result of a failed load_named_event()
was OP_LOAD_ERROR. However since load_named_event() returns bool,
this assert did not make any sense. This patch therefore removes
the assert, fixing the problem. The patch also removes
enum_events_error_code since it was unused.
No test case added. The bug fix is trivial and this bug was
easily detected by RQG tests. Further, adding a MTR test case
for this bug would require adding sync points to make the
test case repeatable.
This patch:
- Moves all definitions from the mysql_priv.h file into
header files for the component where the variable is
defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h
This deadlock could occour betweeen one connection executing
SET GLOBAL EVENT_SCHEDULER= ON and another executing SET GLOBAL
EVENT_SCHEDULER= OFF. The bug was introduced by WL#4738.
The first connection would hold LOCK_event_metadata (protecting
the global variable) while trying to lock LOCK_global_system_variables
starting the event scheduler thread (in THD:init()).
The second connection would hold LOCK_global_system_variables
while trying to get LOCK_event_scheduler after stopping the event
scheduler inside event_scheduler_update().
This patch fixes the problem by not using LOCK_event_metadata to
protect the event_scheduler variable. It is still protected using
LOCK_global_system_variables. This fixes the deadlock as it removes
one of the two mutexes used to produce it.
However, this patch opens up the possibility that the event_scheduler
variable and the real event_scheduler state can become out of sync
(e.g. variable = OFF, but scheduler running). But this can only
happen under very unlikely conditions - two concurrent SET GLOBAL
statments, with one thread interrupted at the exact wrong moment.
This is preferable to having the possibility of a deadlock.
This patch also fixes a bug where it was possible to exit create_event()
without releasing LOCK_event_metadata if running out of memory during
its exection.
No test case added since a repeatable test case would have required
excessive use of new sync points. Instead we rely on the fact that
this bug was easily reproduceable using RGQ tests.
Bug#16565 mysqld --help --verbose does not order variablesBug#20413 sql_slave_skip_counter is not shown in show variables
Bug#20415 Output of mysqld --help --verbose is incomplete
Bug#25430 variable not found in SELECT @@global.ft_max_word_len;
Bug#32902 plugin variables don't know their names
Bug#34599 MySQLD Option and Variable Reference need to be consistent in formatting!
Bug#34829 No default value for variable and setting default does not raise error
Bug#34834 ? Is accepted as a valid sql mode
Bug#34878 Few variables have default value according to documentation but error occurs
Bug#34883 ft_boolean_syntax cant be assigned from user variable to global var.
Bug#37187 `INFORMATION_SCHEMA`.`GLOBAL_VARIABLES`: inconsistent status
Bug#40988 log_output_basic.test succeeded though syntactically false.
Bug#41010 enum-style command-line options are not honoured (maria.maria-recover fails)
Bug#42103 Setting key_buffer_size to a negative value may lead to very large allocations
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
Bug#44797 plugins w/o command-line options have no disabling option in --help
Bug#46314 string system variables don't support expressions
Bug#46470 sys_vars.max_binlog_cache_size_basic_32 is broken
Bug#46586 When using the plugin interface the type "set" for options caused a crash.
Bug#47212 Crash in DBUG_PRINT in mysqltest.cc when trying to print octal number
Bug#48758 mysqltest crashes on sys_vars.collation_server_basic in gcov builds
Bug#49417 some complaints about mysqld --help --verbose output
Bug#49540 DEFAULT value of binlog_format isn't the default value
Bug#49640 ambiguous option '--skip-skip-myisam' (double skip prefix)
Bug#49644 init_connect and \0
Bug#49645 init_slave and multi-byte characters
Bug#49646 mysql --show-warnings crashes when server dies
when there are no up-to-date system tables to support it:
- initialize the scheduler before reporting "Ready for connections".
This ensures that warnings, if any, are printed before "Ready for
connections", and this message is not mangled.
- do not abort the scheduler if there are no system tables
- check the tables once at start up, remember the status and disable
the scheduler if the tables are not up to date.
If one attempts to use the scheduler with bad tables,
issue an error message.
- clean up the behaviour of the module under LOCK TABLES and pre-locking
mode
- make sure implicit commit of Events DDL works as expected.
- add more tests
Collateral clean ups in the events code.
This patch fixes Bug#23631 Events: SHOW VARIABLES doesn't work
when mysql.event is damaged
This patch implements the idea of the bug report by making Event_queue
unaware of Event_db_repository by making a higher level class - Events,
which is aware of most of all classes, responsible for passing all data
needed for adding/updating/deleting an event to/from the queue.
Introduces few new classes :
- Event_worker_thread
- Event_queue_element_for_exec
Remove SHOW SCHEDULER STATUS command and migrate the
information output to `mysqladmin debug` (COM_DEBUG)
SHOW SCHEDULER STATUS was introduced in 5.1.11, provided
some debug information about event scheduler internals and
was enabled only in debug builds.
This is a post-review patch.
Fixes the typelib implementation, available only in 5.1.11.
--event-scheduler cmdline : DISABLED | ON | OFF | 0 | 1
DISABLED - makes the scheduler unavailable during the server run
(ON|1)- When the server is started the scheduler will be started. It can
be stopped and restarted by setting appropriate values to
GLOBAL event_scheduler
(OFF|0)- When the server is started, the scheduler won't be started. It
can be started and again stopped by setting appropriate values to
GLOBAL event_scheduler. _DEFAULT_ value
The GLOBAL variable event_scheduler can have the following values:
OFF | ON | 0 | 1
DISABLED is not possible and every attempt will end with an error that
it's not a valid value for the variable.
OFF | 0 - This is the pre-5.1.11 behavior - The scheduler stops, if not
already stopped, and can be started again by setting
the value of the variable to ON|1.
ON | 1 - This is the pre-5.1.11 behavior - The scheduler starts, if not
already started, and can be stopped again by setting the value
of the variable to OFF|0.
More small fixes to the API : use LEX_STRING instead of LEX_STRING* and if error
then return bool(true) instead of error code.
Merged functions. Reduced usage of sp_name.
Fixed a lot of function documentation errors.
Added function documentation wherever needed.
Removed some unused defines and error codes.
Next to come is batch rename of Event_scheduler_ng to Event_scheduler.
This patch introduces specialized Event data objects
Event_basic as parent.
Event_queue_element used for queue storage
Event_timed used for SHOW EVENTS/ I_S.EVENTS / SHOW CREATE EVENT
Event_job_data using during execution.
Methods were moved out of Event_timed to other classes.
This patch also introduces Events::LOCK_event_metadata.
This patch gives new implementation of Events::dump_internal_status().
Now both the Event_scheduler and Event_queue return information during
their ::dump_internal_status().
Shortened a bit the runtime for executing events test cases.
Cleaned up the code a bit. Fixed few leaks.
This code still does not load events on server startup
from disk. The problem is that there is a need for a THD instance, which
does not exist during server boot. This will be solved soon.
Still Event_timed is used both for the memory queue and for exectution.
This will be changed according to WL#3337 probably in the next commit.
Cut Nr. 8.
All tests pass.
Separated Event_scheduler into Event_queue and Event_scheduler.
Added new Event_scheduler_ng which is the new scheduler and is used
system-wide. Will be moved to the event_scheduler.cc in the future.
Using Event_timed in Event_queue as well as cloned during execution.
Next step is to have Event_worker_data which will be used during execution
and will take ::compile()/::execute() out of Event_timed.
This cut No 7 should finish the part of fixing the parsing of the events :
- Event_timed is no more used during parsing. Less problems because it has
a mutex. Event_parse_data class is used during parsing. It is suited only
for this purpose. It's pretty lightweight
- Late checking of data from parsing is being performed. This should solve
the problems of nested events in SP or other events (for the situation
of no nested bodies). Before if an ALTER EVENT was in a SP, then when the
SP was compiled, and not executed, the actual init_xxx methods of Event_timed
were called, which is wrong.
- It could be a side effect of using a specialized class, but test events_stress is
now 25% quicker.
Cut No8 will start splitting Event_scheduler into 2 parts, the QUEUE will be moved
to Event_queue.
Cut 7 (refactoring)
db_repository is no more embedded in the Events
singleton. Therefore a change to Events_db_repository
won't mean recompile of all files in the server which include events.h
5th cut, moved DB related code to Event_db_repository and
updated accordingly the remanining code.
Moved change/restore_security_context() to class THD
Removed events_priv.h
Next step is to reorganize create/update_event() and parsing for them.
But probably some other refactoring could be done in the meanwhile.
The changes so far pass the test suite.
Third cut to simplify parsing phase. Now DROP EVENT works.
Overloaded few functions to be able to use either sp_name or pass two LEX_STRINGs
instead of a Event_timed pointer. This is transitional and eventually the old
functions will be removed. For now DROP EVENT also works, does not need anymore
a parsing object (Event_timed) and definer initialization because everyone who
has EVENT_ACL can drop events, and this is checked on execution time in sql_parse.cc
from the security context, as it should be.
Unify method naming -> create/update/drop_event
Move class Event_timed to event_timed.h
class Events is in events.h (renamed from event.h)
The implementation is in events.cc (renamed from event.h)
