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.
include/my_global.h:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
define SIZE_T_MAX
include/myisam.h:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
declare 'myisam_mmap_size' and 'myisam_mmap_used' variables and the mutex
THR_LOCK_myisam_mmap
myisam/mi_packrec.c:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
add 'myisam_mmap_size' option which limits the memory available to mmap of
myisam files
myisam/mi_static.c:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
declare 'myisam_mmap_size' and 'myisam_mmap_used' variables and the mutex
THR_LOCK_myisam_mmap
myisam/myisamdef.h:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
move MEMMAP_EXTRA_MARGIN to myisam.h so that it can be used in mysqld.cc
mysql-test/r/variables.result:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
Testcase for BUG#37408 to test the myisam_mmap_size option
mysql-test/t/variables.test:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
Testcase for BUG#37408 to test the myisam_mmap_size option
mysys/my_thr_init.c:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
intialize the lock THR_LOCK_myisam_mmap
sql/mysqld.cc:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
add the 'myisam_mmap_size' option
sql/set_var.cc:
Fix for Bug #37408 - Compressed MyISAM files should not require/use mmap()
add the 'myisam_mmap_size' to the SHOW VARIABLES list
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().
include/my_no_pthread.h:
Dummy my_pthread_once() for single thread use.
include/my_pthread.h:
Declaration for new function my_pthread_once().
mysys/charset.c:
Logic in init_available_charsets() is simplified.
Using my_pthread_once() for all calls to this func.
mysys/my_winthread.c:
Windows implementation of my_pthread_once().
----------------------------------------------------------
revno: 2630.4.38
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-4144
timestamp: Wed 2008-06-25 22:07:06 +0400
message:
WL#4144 - Lock MERGE engine children.
Committing a version of the patch merged with WL#3726
on behalf of Ingo.
Step #1: Move locking from parent to children.
MERGE children are now left in the query list of tables
after inserted there in open_tables(). So they are locked
by lock_tables() as all other tables are.
The MERGE parent does not store locks any more. It appears
in a MYSQL_LOCK with zero lock data. This is kind of a "dummy"
lock.
All other lock handling is also done directly on the children.
To protect against parent or child modifications during LOCK
TABLES, the children are detached after every statement and
attached before every statement, even under LOCK TABLES.
The children table list is removed from the query list of tables
on every detach and on close of the parent.
Step #2: Move MERGE specific functionality from SQL layer
into table handler.
Functionality moved from SQL layer (mainly sql_base.cc)
to the table handler (ha_myisammrg.cc).
Unnecessary code is removed from the SQL layer.
Step #3: Moved all MERGE specific members from TABLE
to ha_myisammrg.
Moved members from TABLE to ha_myisammrg.
Renamed some mebers.
Fixed comments.
Step #4: Valgrind and coverage testing
Valgrind did not uncover new problems.
Added purecov comments.
Added a new test for DATA/INDEX DIRECTORY options.
Changed handling of ::reset() for non-attached children.
Fixed the merge-big test.
Step #5: Fixed crashes detected during review
Changed detection when to attach/detach.
Added new tests.
Backport also the fix for Bug#44040 "MySQL allows creating a
MERGE table upon VIEWs but crashes when using it"
include/my_base.h:
WL#4144 - Lock MERGE engine children
Added HA_EXTRA_ADD_CHILDREN_LIST and HA_EXTRA_IS_ATTACHED_CHILDREN
for MERGE table support
mysql-test/r/merge.result:
WL#4144 - Lock MERGE engine children
Fixed test result.
mysql-test/t/disabled.def:
Enable merge.test, which now is working again (WL#4144).
mysql-test/t/merge-big.test:
Fix the messages for wait_condition (merge with WL#3726).
mysql-test/t/merge.test:
WL#4144 - Lock MERGE engine children
Fixed one test to meet coding standards for tests
(upper case keywords, engine names as in SHOW ENGINES).
Fixed error codes.
Added a test for DATA/INDEX DIRECTORY.
mysys/thr_lock.c:
WL#4144 - Lock MERGE engine children
Added purecov comments.
sql/ha_partition.cc:
WL#4144 - Lock MERGE engine children
Added MERGE specific extra operations to ha_partition::extra().
Extended comments.
Changed function comment to doxygen style.
Fixed nomenclature: 'parameter' -> 'operation'.
sql/mysql_priv.h:
WL#4144 - Lock MERGE engine children
Removed declarations for removed functions.
sql/sql_base.cc:
WL#4144 - Lock MERGE engine children
Leave the children in the query list of tables after open_tables().
Set proper back links (prev_global).
Attach MERGE children before and detach them after every
statement. Even under LOCK TABLES.
Remove children from the query list when they are detached.
Remove lock forwarding from children to parent.
Moved MERGE specific functions to ha_myisammrg.cc.
Added purecov comments.
Backport the fix for Bug#44040 "MySQL allows creating a MERGE table upon VIEWs but crashes when using it"
sql/sql_table.cc:
WL#4144 - Lock MERGE engine children
Changed detection of MERGE tables.
sql/table.cc:
WL#4144 - Lock MERGE engine children
Moved is_children_attached() method from TABLE to ha_myisammrg.
sql/table.h:
WL#4144 - Lock MERGE engine children
Moved all MERGE specific members from TABLE to ha_myisammrg.
storage/myisammrg/ha_myisammrg.cc:
WL#4144 - Lock MERGE engine children
Set proper back links in the child list (prev_global).
Added a function for removal of the child list from the query list.
Remove children from the query list when the parent is closed.
Make parent lock handling a dummy (zero locks).
Moved MERGE specific functionality from SQL layer to here.
Moved all MERGE specific members from TABLE to ha_myisammrg.
Renamed children list pointers.
Added initialization and free for the children list mem_root.
Fixed comments.
Added purecov comments.
storage/myisammrg/ha_myisammrg.h:
WL#4144 - Lock MERGE engine children
Added method add_children_list().
Moved all MERGE specific members from TABLE to ha_myisammrg.
Renamed children list pointers.
Added a mem_root for the children list.
storage/myisammrg/myrg_extra.c:
WL#4144 - Lock MERGE engine children
Changed handling of ::reset() for non-attached children.
