sql/share/errmsg-utf8.txt:
correct the error message, as query_cache_type variable is not read-ony anymore
sql/sql_cache.cc:
the caller should verify that query cache resize
is possible, before trying it
sql/sys_vars.cc:
* test if qc resize is possible in the sysvar on_check() funntion,
not in the on_update() function.
* use the error message that better describes the problem
To allow it, change minimum of thread_pool_stall_limit to be 10 milliseconds.
Also introduce a new parameter to oversubscribe a group . Number of threads running in parallel would be higher than it normally should, leading to thrashing, but it may improving preemptiveness, which is useful for the described corner case.
* rename all debugging related command-line options
and variables to start from "debug-", and made them all
OFF by default.
* replace "MySQL" with "MariaDB" in error messages
* "Cast ... converted ... integer to it's ... complement"
is now a note, not a warning
* @@query_cache_strip_comments now has a session scope,
not global.
handle_segfault is the signal handler code of mysqld. however, it makes
calls to potentially unsafe functions localtime_r, fprintf, fflush.
include/my_stacktrace.h:
Add safe versions of itoa() write() and snprintf().
libmysqld/CMakeLists.txt:
Move signal handler to separate file.
mysys/stacktrace.c:
Remove unsafe function calls.
sql/CMakeLists.txt:
Move signal handler to separate file.
sql/mysqld.cc:
Move signal handler to separate file.
sql/set_var.h:
Add missing #include dependency.
sql/sys_vars.cc:
Cleanup .h and .cc files.
sql/sys_vars.h:
Cleanup .h and .cc files.
BY CACHING OR REDUCING CREATEEVENT CALLS".
5.5 versions of MySQL server performed worse than 5.1 versions
under single-connection workload in autocommit mode on Windows XP.
Part of this slowdown can be attributed to overhead associated
with constant creation/destruction of MDL_lock objects in the MDL
subsystem. The problem is that creation/destruction of these
objects causes creation and destruction of associated
synchronization primitives, which are expensive on Windows XP.
This patch tries to alleviate this problem by introducing a cache
of unused MDL_object_lock objects. Instead of destroying such
objects we put them into the cache and then reuse with a new
key when creation of a new object is requested.
To limit the size of this cache, a new --metadata-locks-cache-size
start-up parameter was introduced.
mysql-test/r/mysqld--help-notwin.result:
Updated test after adding --metadata-locks-cache-size
parameter.
mysql-test/r/mysqld--help-win.result:
Updated test after adding --metadata-locks-cache-size
parameter.
mysql-test/suite/sys_vars/r/metadata_locks_cache_size_basic.result:
Added test coverage for newly introduced --metadata_locks_cache_size
start-up parameter and corresponding global read-only variable.
mysql-test/suite/sys_vars/t/metadata_locks_cache_size_basic-master.opt:
Added test coverage for newly introduced --metadata_locks_cache_size
start-up parameter and corresponding global read-only variable.
mysql-test/suite/sys_vars/t/metadata_locks_cache_size_basic.test:
Added test coverage for newly introduced --metadata_locks_cache_size
start-up parameter and corresponding global read-only variable.
sql/mdl.cc:
Introduced caching of unused MDL_object_lock objects, in order to
avoid costs associated with constant creation and destruction of
such objects in single-connection workloads run in autocommit mode.
Such costs can be pretty high on systems where creation and
destruction of synchronization primitives require a system call
(e.g. Windows XP).
To implement this cache,a list of unused MDL_object_lock instances
was added to MDL_map object. Instead of being destroyed
MDL_object_lock instances are put into this list and re-used later
when creation of a new instance is required. Also added
MDL_lock::m_version counter to allow threads having outstanding
references to an MDL_object_lock instance to notice that it has
been moved to the unused objects list.
Added a global variable for a start-up parameter that limits
the size of the unused objects list.
Note that we don't cache MDL_scoped_lock objects since they
are supposed to be created only during execution of DDL
statements and therefore should not affect performance much.
sql/mdl.h:
Added a global variable for start-up parameter that limits the
size of the unused MDL_object_lock objects list and constant
for its default value.
sql/sql_plist.h:
Added I_P_List<>::pop_front() function.
sql/sys_vars.cc:
Introduced --metadata-locks-cache-size start-up parameter
for specifying size of the cache of unused MDL_object_lock
objects.
BY CACHING OR REDUCING CREATEEVENT CALLS".
5.5 versions of MySQL server performed worse than 5.1 versions
under single-connection workload in autocommit mode on Windows XP.
Part of this slowdown can be attributed to overhead associated
with constant creation/destruction of MDL_lock objects in the MDL
subsystem. The problem is that creation/destruction of these
objects causes creation and destruction of associated
synchronization primitives, which are expensive on Windows XP.
This patch tries to alleviate this problem by introducing a cache
of unused MDL_object_lock objects. Instead of destroying such
objects we put them into the cache and then reuse with a new
key when creation of a new object is requested.
To limit the size of this cache, a new --metadata-locks-cache-size
start-up parameter was introduced.
sql/sql_insert.cc:
CREATE ... IF NOT EXISTS may do nothing, but
it is still not a failure. don't forget to my_ok it.
******
CREATE ... IF NOT EXISTS may do nothing, but
it is still not a failure. don't forget to my_ok it.
sql/sql_table.cc:
small cleanup
******
small cleanup
of service in prepared statements).
sql/sql_prepare.cc:
At mysql_stmt_get_longdata(): instead of pushing an internal
error handler (as done in 5.1-tree) we save, set and restore
the statement's diagnostics area and warning info.
