MDEV-33502 Slowdown when running nested statement with many partitions
This change was triggered to help some MariaDB users with close to
10000 bits in their bitmaps.
- Change underlaying storage to be 64 bit instead of 32bit.
- This reduses number of loops to scan bitmaps.
- This can cause some bitmaps to be 4 byte large.
- Ensure that all not used top-bits are always 0 (simplifes code as
the last 64 bit storage is not a special case anymore).
- Use my_find_first_bit() to find the first set bit which is much faster
than scanning trough things byte by byte and then bit by bit.
Other things:
- Added a bool to remember if my_bitmap_init() did allocate the bitmap
array. my_bitmap_free() will only free arrays it did allocate.
This allowed me to remove setting 'bitmap=0' before calling
my_bitmap_free() for cases where the bitmap's where allocated externally.
- my_bitmap_init() sets bitmap to 0 in case of failure.
- Added 'universal' asserts to most bitmap functions.
- Change all remaining calls to bitmap_init() to my_bitmap_init().
- To finish the change from 2014.
- Changed all usage of uint32 in my_bitmap.h to my_bitmap_map.
- Updated bitmap_copy() to handle bitmaps of different size.
- Removed const from bitmap_exists_intersection() as this caused casts
on all usage.
- Removed not used function bitmap_set_above().
- Renamed create_last_word_mask() to create_last_bit_mask() (to match
name changes in my_bitmap.cc)
- Extended bitmap-t with test for more bitmap functions.
The old code collected a list of THD's, locked the THD's from getting
deleted by locking two mutex and then later in a separate loop
sent a kill signal to each THD.
The problem with this approach is that, as THD's can be reused,
the second time the THD is killed, the mutex can be taken in
different order, which signals failures in safe_mutex.
Fixed by sending the kill signal directly and not collect the THD's
in a list to be signaled later. This is the same approach we are using
in kill_zombie_dump_threads().
Other things:
- Reset safe_mutex_t->locked_mutex when freed (Safety fix)
Other things:
- Added DBUG_EXECUTE_IF("print_allocated_thread_memory") at end of query
to easier find not freed memory allocated by THD
- Removed free_root() from plugin_init() that did nothing.
The leaks are all 40 bytes and happens in this call stack when running
mtr vcol.vcol_syntax:
alloc_root()
...
Virtual_column_info::fix_and_check_exp()
...
Delayed_insert::get_local_table()
The problem was that one copied a MEM_ROOT from THD to a TABLE without
taking into account that new blocks would be allocated through the
TABLE memroot (and would thus be leaked).
In general, one should NEVER copy MEM_ROOT from one object to another
without clearing the copied memroot!
Fixed by, at end of get_local_table(), copy all new allocated objects
to client_thd->mem_root.
Other things:
- Removed references to MEM_ROOT::total_alloc that was wrongly left
after a previous commit
Also fixes: MDEV-30050 Inconsistent results of DISTINCT with NOPAD
Problem:
Key segments for CHAR columns where compared using strnncollsp()
for engines MyISAM and Aria.
This did not work correct in case if the engine applyied trailing
space compression.
Fix:
Replacing ha_compare_text() calls to new functions:
- ha_compare_char_varying()
- ha_compare_char_fixed()
- ha_compare_word()
- ha_compare_word_prefix()
- ha_compare_word_or_prefix()
The code branch corresponding to comparison of CHAR column keys
(HA_KEYTYPE_TEXT segment type) now uses ha_compare_char_fixed()
which calls strnncollsp_nchars().
This patch does not change the behavior for the rest of the code:
- comparison of VARCHAR/TEXT column keys
(HA_KEYTYPE_VARTEXT1, HA_KEYTYPE_VARTEXT2 segments types)
- comparison in the fulltext code
Raise notes if indexes cannot be used:
- in case of data type or collation mismatch (diferent error messages).
- in case if a table field was replaced to something else
(e.g. Item_func_conv_charset) during a condition rewrite.
Added option to write warnings and notes to the slow query log for
slow queries.
New variables added/changed:
- note_verbosity, with is a set of the following options:
basic - All old notes
unusable_keys - Print warnings about keys that cannot be used
for select, delete or update.
explain - Print unusable_keys warnings for EXPLAIN querys.
The default is 'basic,explain'. This means that for old installations
the only notable new behavior is that one will get notes about
unusable keys when one does an EXPLAIN for a query. One can turn all
of all notes by either setting note_verbosity to "" or setting sql_notes=0.
- log_slow_verbosity has a new option 'warnings'. If this is set
then warnings and notes generated are printed in the slow query log
(up to log_slow_max_warnings times per statement).
- log_slow_max_warnings - Max number of warnings written to
slow query log.
Other things:
- One can now use =ALL for any 'set' variable to set all options at once.
For example using "note_verbosity=ALL" in a config file or
"SET @@note_verbosity=ALL' in SQL.
- mysqldump will in the future use @@note_verbosity=""' instead of
@sql_notes=0 to disable notes.
- Added "enum class Data_type_compatibility" and changing the return type
of all Field::can_optimize*() methods from "bool" to this new data type.
Reviewer & Co-author: Alexander Barkov <bar@mariadb.com>
- The code that prints out the notes comes mainly from Alexander
This patch adds support for controlling of memory allocation
done by SP/PS that could happen on second and following executions.
As soon as SP or PS has been executed the first time its memory root
is marked as read only since no further memory allocation should
be performed on it. In case such allocation takes place it leads to
the assert hit for invariant that force no new memory allocations
takes place as soon as the SP/PS has been marked as read only.
The feature for control of memory allocation made on behalf SP/PS
is turned on when both debug build is on and the cmake option
-DWITH_PROTECT_STATEMENT_MEMROOT is set.
The reason for introduction of the new cmake option
-DWITH_PROTECT_STATEMENT_MEMROOT
to control memory allocation of second and following executions of
SP/PS is that for the current server implementation there are too many
places where such memory allocation takes place. As soon as all such
incorrect allocations be fixed the cmake option
-DWITH_PROTECT_STATEMENT_MEMROOT
can be removed and control of memory allocation made on second and
following executions can be turned on only for debug build. Before
every incorrect memory allocation be fixed it makes sense to guard
the checking of memory allocation on read only memory by extra cmake
option else we would get a lot of failing test on buildbot.
Moreover, fixing of all incorrect memory allocations could take pretty
long period of time, so for introducing the feature without necessary
to wait until all places throughout the source code be fixed it makes
sense to add the new cmake option.
Revert the old work-around for buggy fdatasync() on Linux ext3. This bug was
fixed in Linux > 10 years ago back to kernel version at least 3.0.
Reviewed-by: Marko Mäkelä <marko.makela@mariadb.com>
Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>
Docker when mounting a configuration file into a Windows exposes the
file with permission 0777. These world writable files are ignored by
by MariaDB.
Add the access check such that filesystem RO or immutable file is
counted as sufficient protection on the file.
Test:
$ mkdir /tmp/src
$ vi /tmp/src/my.cnf
$ chmod 666 /tmp/src/my.cnf
$ mkdir /tmp/dst
$ sudo mount --bind /tmp/src /tmp/dst -o ro
$ ls -la /tmp/dst
total 4
drwxr-xr-x. 2 dan dan 60 Jun 15 15:12 .
drwxrwxrwt. 25 root root 660 Jun 15 15:13 ..
-rw-rw-rw-. 1 dan dan 10 Jun 15 15:12 my.cnf
$ mount | grep dst
tmpfs on /tmp/dst type tmpfs (ro,seclabel,nr_inodes=1048576,inode64)
strace client/mariadb --defaults-file=/tmp/dst/my.cnf
newfstatat(AT_FDCWD, "/tmp/dst/my.cnf", {st_mode=S_IFREG|0666, st_size=10, ...}, 0) = 0
access("/tmp/dst/my.cnf", W_OK) = -1 EROFS (Read-only file system)
openat(AT_FDCWD, "/tmp/dst/my.cnf", O_RDONLY|O_CLOEXEC) = 3
The one failing test, but this isn't a regression, just not a total fix:
$ chmod u-w /tmp/src/my.cnf
$ ls -la /tmp/src/my.cnf
-r--rw-rw-. 1 dan dan 18 Jun 16 10:22 /tmp/src/my.cnf
$ strace -fe trace=access client/mariadb --defaults-file=/tmp/dst/my.cnf
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
access("/etc/system-fips", F_OK) = -1 ENOENT (No such file or directory)
access("/tmp/dst/my.cnf", W_OK) = -1 EACCES (Permission denied)
Warning: World-writable config file '/tmp/dst/my.cnf' is ignored
Windows test (Docker Desktop ~4.21) which was the important one to fix:
dan@LAPTOP-5B5P7RCK:~$ docker run --rm -v /mnt/c/Users/danie/Desktop/conf:/etc/mysql/conf.d/:ro -e MARIADB_ROOT_PASSWORD=bob quay.io/m
ariadb-foundation/mariadb-devel:10.4-MDEV-27038-ro-mounts-pkgtest ls -la /etc/mysql/conf.d
total 4
drwxrwxrwx 1 root root 512 Jun 15 13:57 .
drwxr-xr-x 4 root root 4096 Jun 15 07:32 ..
-rwxrwxrwx 1 root root 43 Jun 15 13:56 myapp.cnf
root@a59b38b45af1:/# strace -fe trace=access mariadb
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
access("/etc/mysql/conf.d/myapp.cnf", W_OK) = -1 EROFS (Read-only file system)
debug_sync refactoring introduced a statically instantiated object
debug_sync_global of the structure st_debug_sync_globals.
st_debug_sync_globals includes Hash_set<> which allocates memory
in the constructor. sf_malloc() calls _my_thread_var()->dbug_id
which is pthread_getspecific(THR_KEY_mysys), and THR_KEY_mysys is 0
before pthread_key_create(). pthread_getspecific(0) returns a valid
pointer, not EINVAL. And safemalloc dereferences it.
let's statically initialize THR_KEY_mysys to -1, this makes
pthread_getspecific(THR_KEY_mysys) to fail before pthread_key_create()
is called.
followup for 8885225de6
rw_trx_hash_t::find() acquires element->mutex, then unpins pins, used for
lf_hash element search. After that the "element" can be deallocated and
reused by some other thread.
If we take a look rw_trx_hash_t::insert()->lf_hash_insert()->lf_alloc_new()
calls, we will not find any element->mutex acquisition, as it was not
initialized yet before it's allocation. rw_trx_hash_t::insert() can reuse
the chunk, unpinned in rw_trx_hash_t::find().
The scenario is the following:
1. Thread 1 have just executed lf_hash_search() in
rw_trx_hash_t::find(), but have not acquired element->mutex yet.
2. Thread 2 have removed the element from hash table with
rw_trx_hash_t::erase() call.
3. Thread 1 acquired element->mutex and unpinned pin 2 pin with
lf_hash_search_unpin(pins) call.
4. Some thread purged memory of the element.
5. Thread 3 reused the memory for the element, filled element->id,
element->trx.
6. Thread 1 crashes with failed "DBUG_ASSERT(trx_id == trx->id)"
assertion.
Note that trx_t objects are also reused, see the code around trx_pools
for details.
The fix is to invoke "lf_hash_search_unpin(pins);" after element->trx is
stored in local variable in rw_trx_hash_t::find().
Reviewed by: Nikita Malyavin, Marko Mäkelä.
Modern software (including text editors, static analysis software,
and web-based code review interfaces) often requires source code files
to be interpretable via a consistent character encoding, with UTF-8 or
ASCII (a strict subset of UTF-8) as the default. Several of the MariaDB
source files contain bytes that are not valid in either the UTF-8 or
ASCII encodings, but instead represent strings encoded in the
ISO-8859-1/Latin-1 or ISO-8859-2/Latin-2 encodings.
These inconsistent encodings may prevent software from correctly
presenting or processing such files. Converting all source files to
valid UTF8 characters will ensure correct handling.
Comments written in Czech were replaced with lightly-corrected
translations from Google Translate. Additionally, comments describing
the proper handling of special characters were changed so that the
comments are now purely UTF8.
All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer
Amazon Web Services, Inc.
Co-authored-by: Andrew Hutchings <andrew@linuxjedi.co.uk>
MariaDB server prints the stack information if a crash happens.
It traverses the stack frames in function `print_with_addr_resolve`.
For *EACH* frame, it tries to parse the file name and line number of the
frame using `addr2line`, or prints `backtrace_symbols_fd` if `addr2line`
fails.
1. Logic in `addr_resolve` function uses addr2line to get the file name
and line numbers. It has a timeout of 500ms to wait for the response
from addr2line. However, that's not enough on small instances
especially if the debug information is in a separate file or
compressed.
Increase the timeout to 5 seconds to support some edge cases, as
experiments showed addr2line may take 2-3 seconds on some frames.
2. While parsing a frame inside of a shared library using `addr2line`,
the file name and line numbers could be `??`, empty or `0` if the
debug info is not loaded.
It's easy to reproduce when glibc-debuginfo is not installed.
Instead of printing a meaningless frame like:
:0(__GI___poll)[0x1505e9197639]
...
??:0(__libc_start_main)[0x7ffff6c8913a]
We want to print the frame information using `backtrace_symbols_fd`,
with the shared library name and a hexadecimal offset.
Stacktrace example on a real instance with this commit:
/lib64/libc.so.6(__poll+0x49)[0x145cbf71a639]
...
/lib64/libc.so.6(__libc_start_main+0xea)[0x7f4d0034d13a]
`addr_resolve` has considered the case of meaningless combination of
file name and line number returned by `addr2line`. e.g. `??:?`
However, conditions like `:0` and `??:0` are not handled. So now the
function will rollback to `backtrace_symbols_fd` in above cases.
All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.
Replace calls to `sprintf` and `strcpy` by the safer options `snprintf`
and `safe_strcpy` in the following directories:
- libmysqld
- mysys
- sql-common
- strings
All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer
Amazon Web Services, Inc.
This patch also fixes some bugs detected by valgrind after this
patch:
- Not enough copy_func elements was allocated by Create_tmp_table() which
causes an memory overwrite in Create_tmp_table::add_fields()
I added an ASSERT() to be able to detect this also without valgrind.
The bug was that TMP_TABLE_PARAM::copy_fields was not correctly set
when calling create_tmp_table().
- Aria::empty_bits is not allocated if there is no varchar/char/blob
fields in the table. Fixed code to take this into account.
This cannot cause any issues as this is just a memory access
into other Aria memory and the content of the memory would not be used.
- Aria::last_key_buff was not allocated big enough. This may have caused
issues with rtrees and ma_extra(HA_EXTRA_REMEMBER_POS) as they
would use the same memory area.
- Aria and MyISAM didn't take extended key parts into account, which
caused problems when copying rec_per_key from engine to sql level.
- Mark asan builds with 'asan' in version strihng to detect these in
not_valgrind_build.inc.
This is needed to not have main.sp-no-valgrind fail with asan.
__gcov_flush was never an external symbol in the documentation.
It was removed in gcc-11. The correct function to use is __gcov_dump
which is defined in the gcov.h header.
Since 7c58e97 the PSI_memory_key was added to some routines in the
mysys/. This commit fixes synopses of functions that were updated with
the PSI_memory_key parameter.
