This was a deadlock between ALTER TABLE and another DML statement
(or LOCK TABLES ... READ). ALTER TABLE would wait trying to upgrade
its lock to MDL_EXCLUSIVE and the DML statement would wait trying
to acquire a TL_READ_NO_INSERT table level lock.
This could happen if one connection first acquired a MDL_SHARED_READ
lock on a table. In another connection ALTER TABLE is then started.
ALTER TABLE eventually blocks trying to upgrade to MDL_EXCLUSIVE,
but while holding a TL_WRITE_ALLOW_READ table level lock.
If the first connection then tries to acquire TL_READ_NO_INSERT,
it will block and we have a deadlock since neither connection can
proceed.
This patch fixes the problem by allowing TL_READ_NO_INSERT
locks to be granted if another connection holds TL_WRITE_ALLOW_READ
on the same table. This will allow the DML statement to proceed
such that it eventually can release its MDL lock which in turn
makes ALTER TABLE able to proceed.
Note that TL_READ_NO_INSERT was already partially compatible with
TL_WRITE_ALLOW_READ as the latter would be granted if the former
lock was held. This patch just makes the opposite true as well.
Also note that since ALTER TABLE takes an upgradable MDL lock,
there will be no starvation of ALTER TABLE statements by
statements acquiring TL_READ or TL_READ_NO_INSERT.
Test case added to lock_sync.test.
Fix Bug#50555 "handler commands crash server in my_hash_first()"
as a post-merge fix (the new handler tests are not passing
otherwise).
- in hash.c, don't call calc_hash if ! my_hash_inited().
- add tests and results for the test case for Bug#50555
INFILE".
Attempts to execute an INSERT statement for a MEMORY table which invoked
a trigger or called a stored function which tried to perform LOW_PRIORITY
update on the table being inserted into, resulted in debug servers aborting
due to an assertion failure. On non-debug servers such INSERTs failed with
"Can't update table t1 in stored function/trigger because it is already used
by statement which invoked this stored function/trigger" as expected.
The problem was that in the above scenario TL_WRITE_CONCURRENT_INSERT
is converted to TL_WRITE inside the thr_lock() function since the MEMORY
engine does not support concurrent inserts. This triggered an assertion
which assumed that for the same table, one thread always requests locks with
higher thr_lock_type value first. When TL_WRITE_CONCURRENT_INSERT is
upgraded to TL_WRITE after the locks have been sorted, this is no longer true.
In this case, TL_WRITE was requested after acquiring a TL_WRITE_LOW_PRIORITY
lock on the table, triggering the assert.
This fix solves the problem by adjusting this assert to take this
scenario into account.
An alternative approach to change handler::store_locks() methods for all engines
which do not support concurrent inserts in such way that
TL_WRITE_CONCURRENT_INSERT is upgraded to TL_WRITE there instead,
was considered too intrusive.
Commit on behalf of Dmitry Lenev.
Conflicts:
Conflict adding files to server-tools. Created directory.
Conflict because server-tools is not versioned, but has versioned children. Versioned directory.
Conflict adding files to server-tools/instance-manager. Created directory.
Conflict because server-tools/instance-manager is not versioned, but has versioned children. Versioned directory.
Contents conflict in server-tools/instance-manager/instance_map.cc
Contents conflict in server-tools/instance-manager/listener.cc
Contents conflict in server-tools/instance-manager/options.cc
Contents conflict in server-tools/instance-manager/user_map.cc
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 problem is a somewhat common misusage of the strmake function.
The strmake(dst, src, len) function writes at most /len/ bytes to
the string pointed to by src, not including the trailing null byte.
Hence, if /len/ is the exact length of the destination buffer, a
one byte buffer overflow can occur if the length of the source
string is equal to or greater than /len/.
When compressed myisam files are opened, they are always memory mapped
sometimes causing memory swapping problems.
When we mmap the myisam compressed tables of size greater than the memory
available, the kswapd0 process utilization is very high consuming 30-40% of
the cpu. This happens only with linux kernels older than 2.6.9
With newer linux kernels, we don't have this problem of high cpu consumption
and this option may not be required.
The option 'myisam_mmap_size' is added to limit the amount of memory used for
memory mapping of myisam files. This option is not dynamic.
The default value on 32 bit system is 4294967295 bytes and on 64 bit system it
is 18446744073709547520 bytes.
Note: Testcase only tests the option variable. The actual bug has be to
tested manually.
from mysql-next-mr-bugfixing into mysql-trunk-bugfixing.
NOTE: the "utf8_phone_ci" collation does not exist in mysql-trunk yet,
so another collation with 2-byte collation ID is used: "utf8_test_ci".
This patch will be null-merged to mysql-next-mr-bugfixing.
Original revision:
------------------------------------------------------------
revision-id: bar@mysql.com-20091207121153-hs3bqbmr0719ws21
committer: Alexander Barkov <bar@mysql.com>
branch nick: mysql-next-mr.b47756
timestamp: Mon 2009-12-07 16:11:53 +0400
message:
Bug#47756 Setting 2byte collation ID with 'set names' crashes the server
The problem is not actually related to 2byte collation IDs.
The same crash happens if you change the collation ID in
mysql-test/str_data/Index.xml to a value smaller than 256.
Crash happened in SQL parser, because the "ident_map" and "state_map"
arrays were not initialized in loadable utf8 collations.
Fix: adding proper initialization of the "ident_map" and "state_map"
members for loadable utf8 collations.
------------------------------------------------------------
Problem: add_collation did not check that cs->number is smaller
than the number of elements in the array all_charsets[],
so server could crash when loading an Index.xml file with
a collation ID greater the number of elements
(for example when downgrading from 5.5).
Fix: adding a condition to check that cs->number is not out of valid range.
As documented in the bug report, the double checked locking
pattern has inherent issues, and cannot guarantee correct
initialization.
This patch replaces the logic in init_available_charsets()
with the use of pthread_once(3). A wrapper function,
my_pthread_once(), is introduced and is used in lieu of direct
calls to init_available_charsets(). Related defines
MY_PTHREAD_ONCE_* are also introduced.
For the Windows platform, the implementation in lp:sysbench is
ported. For single-thread use, a simple define calls the
function and sets the pthread_once control variable.
Charset initialization is modified to use my_pthread_once().
Bug #42147 Concurrent DML and LOCK TABLE ... READ for InnoDB
table cause warnings in errlog
Concurrent execution of LOCK TABLES ... READ statement and DML statements
affecting the same InnoDB table on debug builds of MySQL server might lead
to "Found lock of type 6 that is write and read locked" warnings appearing
in error log.
The problem is that the table-level locking code allows a thread to acquire
TL_READ_NO_INSERT lock on a table even if there is another thread which holds
TL_WRITE_ALLOW_WRITE lock on the same table. At the same time, the locking
code assumes that that such locks are incompatible (for example, see check_locks()).
This doesn't lead to any problems other than warnings in error log for
debug builds of server since for InnoDB tables TL_READ_NO_INSERT type of
lock is only used for LOCK TABLES and for this statement InnoDB also
performs its own table-level locking.
Unfortunately, the table lock compatibility matrix cannot be updated to disallow
TL_READ_NO_INSERT when another thread holds TL_WRITE_ALLOW_WRITE without
causing starvation of LOCK TABLE READ in InnoDB under high write load.
This patch therefore contains no code changes.
The issue will be fixed later when LOCK TABLE READ has been updated
to not use table locks. This bug will therefore be marked as
"To be fixed later".
Code comment in thr_lock.c expanded to clarify the issue and a
test case based on the bug description added to innodb_mysql_lock.test.
Note that a global suppression rule has been added to both MTR v1 and v2
for the "Found lock of type 6 that is write and read locked" warning.
These suppression rules must be removed once this bug is properly fixed.
The problem is not actually related to 2byte collation IDs.
The same crash happens if you change the collation ID in
mysql-test/str_data/Index.xml to a value smaller than 256.
Crash happened in SQL parser, because the "ident_map" and "state_map"
arrays were not initialized in loadable utf8 collations.
Fix: adding proper initialization of the "ident_map" and "state_map"
members for loadable utf8 collations.
