Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.
Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.
Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost.
The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.
Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.
This patch:
- Moves all definitions from the mysql_priv.h file into
header files for the component where the variable is
defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h
------------------------------------------------------------
revno: 2630.4.37
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w2
timestamp: Wed 2008-06-25 20:28:57 +0400
message:
Fix build failure of mysql-6.0-3726 tree on Windows.
The failure was caused by the fact that sql/mdl.cc was
using __func__ macro without including sql_profile.h
header which contained definition of this macro for
those platforms that miss it.
This patch solves this problem by moving this define to
include/my_global.h which makes it available in modules
which don't/can't include sql/mysql_priv.h.
This is a patch that is part of WL#3726.
"have_profiling"
1) Renamed have_community_features server system variable to
have_profiling.
2) Removed eable-community-features configure option and
ENABLE_COMMUNITY_FEATURES macro.
3) Removed COMMUNITY_SERVER macro and replaced its usage by
ENABLED_PROFILING.
Only --enable-profiling is now needed to enable profiling.
It was the only existing "community feature", so there was
no need for both configure options.
Using --enable-community-features will give a warning message
since it no longer exists.
Between 5.0 and 5.1, the step of incrementing the global query id
changed, which broke how the profiler noticed when a new query had
started. That reset the state list and caused all but the last
five (or so) states to be thrown away.
Now, don't watch for query_id changes in the lower level.
Add a bogus state change at the end of profiling so that the last
real state change is timed.
Emit source reference for the start of the span of time instead of
the end of it.
profiling. Also,
Bug#26938: profiling client hang if used before enabled
In the SHOW command, not sending header data because we had no
rows to send was a protocol violation. Porting the SHOW PROFILE
command to use the Information Schema table avoids that problem.
renamed. Some new THD proc_info states are new. Directories must be
encountered in make in a specific order, to have symlinks already set.
Move community-server-specific tests into own tests, so that we can
exempt them from testing on enterprise servers.
Add a new autoconf paremeter --{en,dis}able-community-features . The
default is disable for enterprise servers.
Though this is a 5.0 tree, it is only to be merged into the 5.0-community
tree and the global 5.1 tree, never to the 5.0-enterprise tree.
halfway through a query (as happens in "SET SESSION PROFILING = ...")
has a few side-effects, the worst of which is a memory leak for
prepared statements, which poke directly from the parser into the
profiling code (we don't have the query text when we need it) and
that overwrites a pointer to heap-allocated memory when the previous
statement turns on profiling.
Instead, now set a flag when we begin a new statement that tracks
whether profiling is on _at the start_ of the query. Use that to
track whether we gather info.
Additionally, use that AND use the state of the profiling variable
after the end of a query to know whether to store information about
the query that just finished.
B-g#24795: SHOW PROFILE implementation
Don't use memory roots to store profiling information, because
memory roots make freeing the data a no-op, and thus long-running
processes with profiling turned on the whole time could eventually
use all available memory.
Instead, use regular heap allocation and deallocation calls to
manage profiling data. Replace the leaky List usage with a similar-
behaving structure named "Queue".
Expand float size to avoid assert()ion failures.
"_db_func_" isn't a known linked object on some platforms, possibly
because it is occasionaly shadowed by DBUG variables. Avoid that
confusion.
to a single statement.
---
Bug#24795: SHOW PROFILE
Profiling is only partially functional on some architectures. Where
there is no getrusage() system call, presently Null values are
returned where it would be required. Notably, Windows needs some love
applied to make it as useful.
Syntax this adds:
SHOW PROFILES
SHOW PROFILE [types] [FOR QUERY n] [OFFSET n] [LIMIT n]
where "n" is an integer
and "types" is zero or many (comma-separated) of
"CPU"
"MEMORY" (not presently supported)
"BLOCK IO"
"CONTEXT SWITCHES"
"PAGE FAULTS"
"IPC"
"SWAPS"
"SOURCE"
"ALL"
It also adds a session variable (boolean) "profiling", set to "no"
by default, and (integer) profiling_history_size, set to 15 by
default.
This patch abstracts setting THDs' "proc_info" behind a macro that
can be used as a hook into the profiling code when profiling
support is compiled in. All future code in this line should use
that mechanism for setting thd->proc_info.
---
Tests are now set to omit the statistics.
---
Adds an Information_schema table, "profiling" for access to
"show profile" data.
---
Merge zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.0-community-3--bug24795
into zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.0-community
---
Fix merge problems.
---
Fixed one bug in the query_source being NULL.
Updated test results.
---
Include more thorough profiling tests.
Improve support for prepared statements.
Use session-specific query IDs, starting at zero.
---
Selecting from I_S.profiling is no longer quashed in profiling, as
requested by Giuseppe.
Limit the size of captured query text.
No longer log queries that are zero length.
