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
The reason for the deadlock was an improper exit from
MDL_context::wait_for_locks() which caused mysys_var->current_mutex to remain
LOCK_mdl even though LOCK_mdl was no longer held by that connection.
This could for example lead to a deadlock in the following way:
1) INSERT DELAYED tries to open a table but fails, and trying to recover it
calls wait_for_locks().
2) Due to a pending exclusive request, wait_for_locks() fails and exits without
resetting mysys_var->current_mutex for the delayed insert handler thread. So it
continues to point to LOCK_mdl.
3) The handler thread manages to open a table.
4) A different connection takes LOCK_open and tries to take LOCK_mdl.
5) FLUSH TABLES from a third connection notices that the handler thread has a
table open, and tries to kill it. This involves locking mysys_var->current_mutex
while having LOCK_open locked. Since current_mutex mistakenly points to LOCK_mdl,
we have a deadlock.
This patch makes sure MDL_EXIT_COND() is called before exiting wait_for_locks().
This clears mysys->current_mutex which resolves the issue.
An assert is added to recover_from_failed_open_table_attempt() after
wait_for_locks() is called, to check that current_mutex is indeed reset.
With this assert in place, existing tests in (e.g.) mdl_sync.test will fail
without this patch.
The reason for the deadlock was an improper exit from
MDL_context::wait_for_locks() which caused mysys_var->current_mutex to remain
LOCK_mdl even though LOCK_mdl was no longer held by that connection.
This could for example lead to a deadlock in the following way:
1) INSERT DELAYED tries to open a table but fails, and trying to recover it
calls wait_for_locks().
2) Due to a pending exclusive request, wait_for_locks() fails and exits without
resetting mysys_var->current_mutex for the delayed insert handler thread. So it
continues to point to LOCK_mdl.
3) The handler thread manages to open a table.
4) A different connection takes LOCK_open and tries to take LOCK_mdl.
5) FLUSH TABLES from a third connection notices that the handler thread has a
table open, and tries to kill it. This involves locking mysys_var->current_mutex
while having LOCK_open locked. Since current_mutex mistakenly points to LOCK_mdl,
we have a deadlock.
This patch makes sure MDL_EXIT_COND() is called before exiting wait_for_locks().
This clears mysys->current_mutex which resolves the issue.
An assert is added to recover_from_failed_open_table_attempt() after
wait_for_locks() is called, to check that current_mutex is indeed reset.
With this assert in place, existing tests in (e.g.) mdl_sync.test will fail
without this patch.
-----------------------------------------------------------
2630.28.28 Magne Mahre 2008-12-05
Bug #38661 'all threads hang in "opening tables" or "waiting for table"
and cpu is at 100%'
Concurrent execution of FLUSH TABLES statement and at least two statements
using the same table might have led to live-lock which caused all three
connections to stall and hog 100% of CPU.
tdc_wait_for_old_versions() wrongly assumed that there cannot be a share
with an old version and no used TABLE instances and thus was failing to
perform wait in situation when such old share was cached in MDL subsystem
thanks to a still active metadata lock on the table. So it might have
happened that two or more connections simultaneously executing statements
which involve table being flushed managed to prevent each other from
waiting in this function by keeping shared metadata lock on the table
constantly active (i.e. one of the statements managed to take/hold this
lock while other statements were calling tdc_wait_for_old_versions()).
Thus they were forcing each other to loop infinitely in open_tables() -
close_thread_tables_for_reopen() - tdc_wait_for_old_versions() cycle
causing CPU hogging.
This patch fixes this problem by removing this false assumption from
tdc_wait_for_old_versions().
Note that the problem is specific only for server versions >= 6.0.
No test case is submitted for this test, as the test infrastructure
hasn't got the necessary primitives to test the behaviour. The
manifestation is that throughput will decrease to a low level
(possibly 0) after some time, and stay at that level. Several
transactions will not complete.
Manual testing can be done by running the code submitted by Shane
Bester attached to the bug report. If the bug persists, the
transaction thruput will almost immediately drop to near zero
(shown as the transaction count output from the test program staying
on a close to constant value, instead of increasing rapidly).
-----------------------------------------------------------
2630.28.28 Magne Mahre 2008-12-05
Bug #38661 'all threads hang in "opening tables" or "waiting for table"
and cpu is at 100%'
Concurrent execution of FLUSH TABLES statement and at least two statements
using the same table might have led to live-lock which caused all three
connections to stall and hog 100% of CPU.
tdc_wait_for_old_versions() wrongly assumed that there cannot be a share
with an old version and no used TABLE instances and thus was failing to
perform wait in situation when such old share was cached in MDL subsystem
thanks to a still active metadata lock on the table. So it might have
happened that two or more connections simultaneously executing statements
which involve table being flushed managed to prevent each other from
waiting in this function by keeping shared metadata lock on the table
constantly active (i.e. one of the statements managed to take/hold this
lock while other statements were calling tdc_wait_for_old_versions()).
Thus they were forcing each other to loop infinitely in open_tables() -
close_thread_tables_for_reopen() - tdc_wait_for_old_versions() cycle
causing CPU hogging.
This patch fixes this problem by removing this false assumption from
tdc_wait_for_old_versions().
Note that the problem is specific only for server versions >= 6.0.
No test case is submitted for this test, as the test infrastructure
hasn't got the necessary primitives to test the behaviour. The
manifestation is that throughput will decrease to a low level
(possibly 0) after some time, and stay at that level. Several
transactions will not complete.
Manual testing can be done by running the code submitted by Shane
Bester attached to the bug report. If the bug persists, the
transaction thruput will almost immediately drop to near zero
(shown as the transaction count output from the test program staying
on a close to constant value, instead of increasing rapidly).
----------------------------------------------------
2736.2.10 Michael Widenius 2008-10-22
Fix for bug#39395 Maria: ma_extra.c:286: maria_extra:
Assertion `share->reopen == 1' failed
sql/sql_base.cc:
Race condition in wait_while_table_is_used() where a table used
by another connection could be forced closed, but there was no protection against the other thread re-opening the table and trying to lock it
again before the table was name locked by original thread.
(diagnostics_area)
Execution of CREATE TABLE ... SELECT statement was not atomic in
the sense that concurrent statements trying to affect its target
table might have sneaked in between the moment when the table was
created and moment when it was filled according to SELECT clause.
This resulted in inconsistent binary log, unexpected target table
contents. In cases when concurrent statement was a DDL statement
CREATE TABLE ... SELECT might have failed with ER_CANT_LOCK error.
In more detail:
Due to premature metadata lock downgrade which occured after CREATE
TABLE SELECT statement created table but before it managed to obtain
table-level lock on it other statements were allowed to open, lock
and change target table in the middle of CREATE TABLE SELECT
execution. This also meant that it was possible that CREATE TABLE
SELECT would wait in mysql_lock_tables() when it was called for newly
created table and that this wait could have been aborted by concurrent
DDL. The latter led to execution of unexpected branch of code and
CREATE TABLE SELECT ending with ER_CANT_LOCK error.
The premature downgrade occured because open_table(), which was called
for newly created table, decided that it is OK to downgrade metadata
lock from exclusive to shared since table exists, even although it
was not acquired within this call.
This fix ensures that open_table() does not downgrade metadata lock
if it is not acquired during its current invocation.
Testing:
The bug is exposed in a race condition, and is thus difficult to
expose in a standard mysql-test-run test case. Instead, a stress
test using the Random Query Generator (https://launchpad.net/randgen)
will trip the problem occasionally.
% perl runall.pl \
--basedir=<build dir> \
--mysqld=--table-lock-wait-timeout=5 \
--mysqld=--skip-safemalloc \
--grammar=conf/maria_bulk_insert.yy \
--reporters=ErrorLog,Backtrace,WinPackage \
--mysqld=--log-output=file \
--queries=100000 \
--threads=10 \
--engine=myisam
Note: You will need a debug build to expose the bug
When the bug is tripped, the server will abort and dump core.
Backport from 6.0-codebase (revid: 2617.53.4)
(diagnostics_area)
Execution of CREATE TABLE ... SELECT statement was not atomic in
the sense that concurrent statements trying to affect its target
table might have sneaked in between the moment when the table was
created and moment when it was filled according to SELECT clause.
This resulted in inconsistent binary log, unexpected target table
contents. In cases when concurrent statement was a DDL statement
CREATE TABLE ... SELECT might have failed with ER_CANT_LOCK error.
In more detail:
Due to premature metadata lock downgrade which occured after CREATE
TABLE SELECT statement created table but before it managed to obtain
table-level lock on it other statements were allowed to open, lock
and change target table in the middle of CREATE TABLE SELECT
execution. This also meant that it was possible that CREATE TABLE
SELECT would wait in mysql_lock_tables() when it was called for newly
created table and that this wait could have been aborted by concurrent
DDL. The latter led to execution of unexpected branch of code and
CREATE TABLE SELECT ending with ER_CANT_LOCK error.
The premature downgrade occured because open_table(), which was called
for newly created table, decided that it is OK to downgrade metadata
lock from exclusive to shared since table exists, even although it
was not acquired within this call.
This fix ensures that open_table() does not downgrade metadata lock
if it is not acquired during its current invocation.
Testing:
The bug is exposed in a race condition, and is thus difficult to
expose in a standard mysql-test-run test case. Instead, a stress
test using the Random Query Generator (https://launchpad.net/randgen)
will trip the problem occasionally.
% perl runall.pl \
--basedir=<build dir> \
--mysqld=--table-lock-wait-timeout=5 \
--mysqld=--skip-safemalloc \
--grammar=conf/maria_bulk_insert.yy \
--reporters=ErrorLog,Backtrace,WinPackage \
--mysqld=--log-output=file \
--queries=100000 \
--threads=10 \
--engine=myisam
Note: You will need a debug build to expose the bug
When the bug is tripped, the server will abort and dump core.
Backport from 6.0-codebase (revid: 2617.53.4)
2630.16.14 Sergei Golubchik 2008-08-25
fixed a crash in partition tests
introduced by HA_EXTRA_PREPARE_FOR_DROP patch
sql/sql_base.cc:
Don't call ::extra() for closed tables.
Bug #46654 False deadlock on concurrent DML/DDL with partitions,
inconsistent behavior
The problem was that if one connection is running a multi-statement
transaction which involves a single partitioned table, and another
connection attempts to alter the table, the first connection gets
ER_LOCK_DEADLOCK and cannot proceed anymore, even when the ALTER TABLE
statement in another connection has timed out or failed.
The reason for this was that the prepare phase for ALTER TABLE for
partitioned tables removed all instances of the table from the table
definition cache before it started waiting on the lock. The transaction
running in the first connection would notice this and report ER_LOCK_DEADLOCK.
This patch changes the prep_alter_part_table() ALTER TABLE code so that
tdc_remove_table() is no longer called. Instead, only the TABLE instance
changed by prep_alter_part_table() is marked as needing reopen.
The patch also removes an unnecessary call to tdc_remove_table() from
mysql_unpack_partition() as the changed TABLE object is destroyed by the
caller at a later point.
Test case added in partition_sync.test.
Bug #46654 False deadlock on concurrent DML/DDL with partitions,
inconsistent behavior
The problem was that if one connection is running a multi-statement
transaction which involves a single partitioned table, and another
connection attempts to alter the table, the first connection gets
ER_LOCK_DEADLOCK and cannot proceed anymore, even when the ALTER TABLE
statement in another connection has timed out or failed.
The reason for this was that the prepare phase for ALTER TABLE for
partitioned tables removed all instances of the table from the table
definition cache before it started waiting on the lock. The transaction
running in the first connection would notice this and report ER_LOCK_DEADLOCK.
This patch changes the prep_alter_part_table() ALTER TABLE code so that
tdc_remove_table() is no longer called. Instead, only the TABLE instance
changed by prep_alter_part_table() is marked as needing reopen.
The patch also removes an unnecessary call to tdc_remove_table() from
mysql_unpack_partition() as the changed TABLE object is destroyed by the
caller at a later point.
Test case added in partition_sync.test.
Bug#42546 Backup: RESTORE fails, thinking it finds an existing table
The problem occured when a MDL locking conflict happened for a non-existent
table between a CREATE and a INSERT statement. The code for CREATE
interpreted this lock conflict to mean that the table existed,
which meant that the statement failed when it should not have.
The problem could occur for CREATE TABLE, CREATE TABLE LIKE and
ALTER TABLE RENAME.
This patch fixes the problem for CREATE TABLE and CREATE TABLE LIKE.
It is based on code backported from the mysql-6.1-fk tree written
by Dmitry Lenev. CREATE now uses normal open_and_lock_tables() code
to acquire exclusive locks. This means that for the test case in the bug
description, CREATE will wait until INSERT completes so that it can
get the exclusive lock. This resolves the reported bug.
The patch also prohibits CREATE TABLE and CREATE TABLE LIKE under
LOCK TABLES. Note that this is an incompatible change and must
be reflected in the documentation. Affected test cases have been
updated.
mdl_sync.test contains tests for CREATE TABLE and CREATE TABLE LIKE.
Fixing the issue for ALTER TABLE RENAME is beyond the scope of this
patch. ALTER TABLE cannot be prohibited from working under LOCK TABLES
as this could seriously impact customers and a proper fix would require
a significant rewrite.
Bug#42546 Backup: RESTORE fails, thinking it finds an existing table
The problem occured when a MDL locking conflict happened for a non-existent
table between a CREATE and a INSERT statement. The code for CREATE
interpreted this lock conflict to mean that the table existed,
which meant that the statement failed when it should not have.
The problem could occur for CREATE TABLE, CREATE TABLE LIKE and
ALTER TABLE RENAME.
This patch fixes the problem for CREATE TABLE and CREATE TABLE LIKE.
It is based on code backported from the mysql-6.1-fk tree written
by Dmitry Lenev. CREATE now uses normal open_and_lock_tables() code
to acquire exclusive locks. This means that for the test case in the bug
description, CREATE will wait until INSERT completes so that it can
get the exclusive lock. This resolves the reported bug.
The patch also prohibits CREATE TABLE and CREATE TABLE LIKE under
LOCK TABLES. Note that this is an incompatible change and must
be reflected in the documentation. Affected test cases have been
updated.
mdl_sync.test contains tests for CREATE TABLE and CREATE TABLE LIKE.
Fixing the issue for ALTER TABLE RENAME is beyond the scope of this
patch. ALTER TABLE cannot be prohibited from working under LOCK TABLES
as this could seriously impact customers and a proper fix would require
a significant rewrite.
------------------------------------------------------------
revno: 2617.68.25
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg-pre2-2
timestamp: Wed 2009-09-16 18:26:50 +0400
message:
Follow-up for one of pre-requisite patches for fixing bug #30977
"Concurrent statement using stored function and DROP FUNCTION
breaks SBR".
Made enum_mdl_namespace enum part of MDL_key class and removed MDL_
prefix from the names of enum members. In order to do the latter
changed name of PROCEDURE symbol to PROCEDURE_SYM (otherwise macro
which was automatically generated for this symbol conflicted with
MDL_key::PROCEDURE enum member).
------------------------------------------------------------
revno: 2617.68.25
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg-pre2-2
timestamp: Wed 2009-09-16 18:26:50 +0400
message:
Follow-up for one of pre-requisite patches for fixing bug #30977
"Concurrent statement using stored function and DROP FUNCTION
breaks SBR".
Made enum_mdl_namespace enum part of MDL_key class and removed MDL_
prefix from the names of enum members. In order to do the latter
changed name of PROCEDURE symbol to PROCEDURE_SYM (otherwise macro
which was automatically generated for this symbol conflicted with
MDL_key::PROCEDURE enum member).
