Fixed race condition in code filling INFORMATION_SCHEMA.PROCESSLIST.INFO_BINARY.
When loading query string/length of another connection one must have
LOCK_thd_data locked.
- Part 4: Removing calls to sql_alloc() and sql_calloc()
Other things:
- Added current_thd in some places to make it clear that it's called (easier to remove later)
- Move memory allocation from Item_func_case::fix_length_and_dec() to Item_func_case::fix_fields()
- Added mem_root to some new calls
- Fixed some wrong UNINIT_VAR() calls
- Fixed a bug in generate_partition_syntax() in case of errors
- Added mem_root to argument to new thread_info
- Simplified my_parse_error() call in sql_yacc.yy
- Part 3: Adding mem_root to push_back() and push_front()
Other things:
- Added THD as an argument to some partition functions.
- Added memory overflow checking for XML tag's in read_xml()
- Added mem_root to all calls to new Item
- Added private method operator new(size_t size) to Item to ensure that
we always use a mem_root when creating an item.
This saves use once call to current_thd per Item creation
Added mandatory thd parameter to Item (and all derivative classes) constructor.
Added thd parameter to all routines that may create items.
Also removed "current_thd" from Item::Item. This reduced number of
pthread_getspecific() calls from 290 to 177 per OLTP RO transaction.
In galera, like other DDLs, CREATE/ALTER VIEW commands are recreated
and replicated during parsing. The ALGORITHM clause is internally set
to VIEW_ALGORITHM_INHERIT if its not explicitly specified by the user.
But since its not a valid type to be used in a command, it leads to an
assertion failure. The solution is to not include the ALGORITHM clause
in the command if its not explicitly specified (or INHERIT).
- Changed ER(ER_...) to ER_THD(thd, ER_...) when thd was known or if there was many calls to current_thd in the same function.
- Changed ER(ER_..) to ER_THD_OR_DEFAULT(current_thd, ER...) in some places where current_thd is not necessary defined.
- Removing calls to current_thd when we have access to thd
Part of this is optimization (not calling current_thd when not needed),
but part is bug fixing for error condition when current_thd is not defined
(For example on startup and end of mysqld)
Notable renames done as otherwise a lot of functions would have to be changed:
- In JOIN structure renamed:
examined_rows -> join_examined_rows
record_count -> join_record_count
- In Field, renamed new_field() to make_new_field()
Other things:
- Added DBUG_ASSERT(thd == tmp_thd) in Item_singlerow_subselect() just to be safe.
- Removed old 'tab' prefix in JOIN_TAB::save_explain_data() and use members directly
- Added 'thd' as argument to a few functions to avoid calling current_thd.
Initialize abs_timeout when it is about to be used. This saves one my_hrtime()
call on hot path (when we acquire MDL lock without waiting).
When filling I_S.PROCESSLIST use THD::start_utime/THD::utime_after_query instead
of THD::start_time. This allows us to save 2 clock_gettime() calls.
Overhead change:
__clock_gettime 0.13% -> 0.11% (122 -> 76 calls per OLTP RO transaction)
my_interval_timer 0.07% -> 0.06%
my_hrtime 0.04% -> 0.01%
THD::enter_stage() optimizations:
- stage backup code moved to THD::backup_stage(), saves one condition
- moved check for "new_stage" out to callers that actually need it
- remnants of enter_stage() moved to sql_class.h so it can be inlined
THD::enter_stage() overhead dropped 0.48% -> 0.07%.
PROFILING::status_change() optimizations:
- "status_arg" is now checked by QUERY_PROFILE::new_status()
- no need to check "enabled": !enabled && current is impossible
- remnants of status_change() moved to sql_profile.h so it can be inlined
PROFILING::status_change() overhead dropped 0.1% -> out of radar.
The bug was that open_tables() returned error in case of
thd->killed() without properly calling thd->send_kill_message()
to set the correct error. This was fixed already in get_schema_column_record,
so the code was just copied to get_geometry_column_record.
