innodb_buffer_pool_size_auto_min: A minimum innodb_buffer_pool_size that
a Linux memory pressure event can lead to shrinking the buffer pool to.
On a memory pressure event, we will attempt to shrink
innodb_buffer_pool_size halfway between its current value and
innodb_buffer_pool_size_auto_min. If innodb_buffer_pool_size_auto_min is
specified as 0 or not specified on startup, its default value will be
adjusted to innodb_buffer_pool_size_max, that is, memory pressure events
will be disregarded by default.
buf_pool_t::garbage_collect(): For up to 15 seconds, attempt to shrink
the buffer pool in response to a memory pressure event.
Reviewed by: Debarun Banerjee
We deprecate and ignore the parameter innodb_buffer_pool_chunk_size
and let the buffer pool size to be changed in arbitrary 1-megabyte
increments.
innodb_buffer_pool_size_max: A new read-only startup parameter
that specifies the maximum innodb_buffer_pool_size. If 0 or
unspecified, it will default to the specified innodb_buffer_pool_size
rounded up to the allocation unit (2 MiB or 8 MiB). The maximum value
is 4GiB-2MiB on 32-bit systems and 16EiB-8MiB on 64-bit systems.
This maximum is very likely to be limited further by the operating system.
The status variable Innodb_buffer_pool_resize_status will reflect
the status of shrinking the buffer pool. When no shrinking is in
progress, the string will be empty.
Unlike before, the execution of SET GLOBAL innodb_buffer_pool_size
will block until the requested buffer pool size change has been
implemented, or the execution is interrupted by a KILL statement
a client disconnect, or server shutdown. If the
buf_flush_page_cleaner() thread notices that we are running out of
memory, the operation may fail with ER_WRONG_USAGE.
SET GLOBAL innodb_buffer_pool_size will be refused
if the server was started with --large-pages (even if
no HugeTLB pages were successfully allocated). This functionality
is somewhat exercised by the test main.large_pages, which now runs
also on Microsoft Windows. On Linux, explicit HugeTLB mappings are
apparently excluded from the reported Redident Set Size (RSS), and
apparently unshrinkable between mmap(2) and munmap(2).
The buffer pool will be mapped to a contiguous virtual memory area
that will be aligned and partitioned into extents of 8 MiB on
64-bit systems and 2 MiB on 32-bit systems.
Within an extent, the first few innodb_page_size blocks contain
buf_block_t objects that will cover the page frames in the rest
of the extent. The number of such frames is precomputed in the
array first_page_in_extent[] for each innodb_page_size.
In this way, there is a trivial mapping between
page frames and block descriptors and we do not need any
lookup tables like buf_pool.zip_hash or buf_pool_t::chunk_t::map.
We will always allocate the same number of block descriptors for
an extent, even if we do not need all the buf_block_t in the last
extent in case the innodb_buffer_pool_size is not an integer multiple
of the of extents size.
The minimum innodb_buffer_pool_size is 256*5/4 pages. At the default
innodb_page_size=16k this corresponds to 5 MiB. However, now that the
innodb_buffer_pool_size includes the memory allocated for the block
descriptors, the minimum would be innodb_buffer_pool_size=6m.
my_large_virtual_alloc(): A new function, similar to my_large_malloc().
my_virtual_mem_reserve(), my_virtual_mem_commit(),
my_virtual_mem_decommit(), my_virtual_mem_release():
New interface mostly by Vladislav Vaintroub, to separately
reserve and release virtual address space, as well as to
commit and decommit memory within it.
After my_virtual_mem_decommit(), the virtual memory range will be
read-only or unaccessible, depending on whether the build option
cmake -DHAVE_UNACCESSIBLE_AFTER_MEM_DECOMMIT=1
has been specified. This option is hard-coded on Microsoft Windows,
where VirtualMemory(MEM_DECOMMIT) will make the memory unaccessible.
On IBM AIX, Linux, Illumos and possibly Apple macOS, the virtual memory
will be zeroed out immediately. On other POSIX-like systems,
madvise(MADV_FREE) will be used if available, to give the operating
system kernel a permission to zero out the virtual memory range.
We prefer immediate freeing so that the reported
resident set size (RSS) of the process will reflect the current
innodb_buffer_pool_size. Shrinking the buffer pool is a rarely
executed resource intensive operation, and the immediate configuration
of the MMU mappings should not incur significant additional penalty.
opt_super_large_pages: Declare only on Solaris. Actually, this is
specific to the SPARC implementation of Solaris, but because we
lack access to a Solaris development environment, we will not revise
this for other MMU and ISA.
buf_pool_t::chunk_t::create(): Remove.
buf_pool_t::create(): Initialize all n_blocks of the buf_pool.free list.
buf_pool_t::allocate(): Renamed from buf_LRU_get_free_only().
buf_pool_t::LRU_warned: Changed to Atomic_relaxed<bool>,
only to be modified by the buf_flush_page_cleaner() thread.
buf_pool_t::shrink(): Attempt to shrink the buffer pool.
There are 3 possible outcomes: SHRINK_DONE (success),
SHRINK_IN_PROGRESS (the caller may keep trying),
and SHRINK_ABORT (we seem to be running out of buffer pool).
While traversing buf_pool.LRU, release the contended
buf_pool.mutex once in every 32 iterations in order to
reduce starvation. Use lru_scan_itr for efficient traversal,
similar to buf_LRU_free_from_common_LRU_list().
buf_pool_t::shrunk(): Update the reduced size of the buffer pool
in a way that is compatible with buf_pool_t::page_guess(),
and invoke my_virtual_mem_decommit().
buf_pool_t::resize(): Before invoking shrink(), run one batch of
buf_flush_page_cleaner() in order to prevent LRU_warn().
Abort if shrink() recommends it, or no blocks were withdrawn in
the past 15 seconds, or the execution of the statement
SET GLOBAL innodb_buffer_pool_size was interrupted.
buf_pool_t::first_to_withdraw: The first block descriptor that is
out of the bounds of the shrunk buffer pool.
buf_pool_t::withdrawn: The list of withdrawn blocks.
If buf_pool_t::resize() is aborted before shrink() completes,
we must be able to resurrect the withdrawn blocks in the free list.
buf_pool_t::contains_zip(): Added a parameter for the
number of least significant pointer bits to disregard,
so that we can find any pointers to within a block
that is supposed to be free.
buf_pool_t::is_shrinking(): Return the total number or blocks that
were withdrawn or are to be withdrawn.
buf_pool_t::to_withdraw(): Return the number of blocks that will need to
be withdrawn.
buf_pool_t::usable_size(): Number of usable pages, considering possible
in-progress attempt at shrinking the buffer pool.
buf_pool_t::page_guess(): Try to buffer-fix a guessed block pointer.
If HAVE_UNACCESSIBLE_AFTER_MEM_DECOMMIT is set, the pointer will
be validated before being dereferenced.
buf_pool_t::get_info(): Replaces buf_stats_get_pool_info().
innodb_init_param(): Refactored. We must first compute
srv_page_size_shift and then determine the valid bounds of
innodb_buffer_pool_size.
buf_buddy_shrink(): Replaces buf_buddy_realloc().
Part of the work is deferred to buf_buddy_condense_free(),
which is being executed when we are not holding any
buf_pool.page_hash latch.
buf_buddy_condense_free(): Do not relocate blocks.
buf_buddy_free_low(): Do not care about buffer pool shrinking.
This will be handled by buf_buddy_shrink() and
buf_buddy_condense_free().
buf_buddy_alloc_zip(): Assert !buf_pool.contains_zip()
when we are allocating from the binary buddy system.
Previously we were asserting this on multiple recursion levels.
buf_buddy_block_free(), buf_buddy_free_low():
Assert !buf_pool.contains_zip().
buf_buddy_alloc_from(): Remove the redundant parameter j.
buf_flush_LRU_list_batch(): Add the parameter to_withdraw
to keep track of buf_pool.n_blocks_to_withdraw.
buf_do_LRU_batch(): Skip buf_free_from_unzip_LRU_list_batch()
if we are shrinking the buffer pool. In that case, we want
to minimize the page relocations and just finish as quickly
as possible.
trx_purge_attach_undo_recs(): Limit purge_sys.n_pages_handled()
in every iteration, in case the buffer pool is being shrunk
in the middle of a purge batch.
Reviewed by: Debarun Banerjee
In commit bda40ccb85 (MDEV-34803)
there was a spelling mistake that somehow causes the deprecated
parameter innodb_purge_rseg_truncate_frequency to be rejected
at server startup.
The functions MY_CHARSET_HANDLER::caseup() and MY_CHARSET_HANDLER::casedn()
in their virtual imlementations do "const char *end= src + srclen"
in the very beginning. Therefore src cannot be NULL to avoid
"UBSAN: SUMMARY: UndefinedBehaviorSanitizer: nullptr-with-offset".
Adding DBUG_ASSERT(src != NULL) into all virtual implementations,
to catch this problem in regular Debug builds (without UBSAN).
Fixing Master_info_index::get_master_info() to check connection_name->str.
If it is NULL then passing empty_clex_str into IdentBufferCasedn
instead of *connection_name.
innodb_log_file_mmap: Use a constant documentation string that
refers to persistent memory also when it is not available in the build.
HAVE_INNODB_MMAP: Remove, and unconditionally enable this code.
log_mmap(): On 32-bit systems, ensure that the size fits in 32 bits.
log_t::resize_start(), log_t::resize_abort(): Only handle memory-mapping
if HAVE_PMEM is defined. The generic memory-mapped interface is only for
reading the log in recovery. Writable memory mappings are only for
persistent memory, that is, Linux file systems with mount -o dax.
Reviewed by: Debarun Banerjee, Otto Kekäläinen
This commit updates default memory allocations size used with MEM_ROOT
objects to minimize the number of calls to malloc().
Changes:
- Updated MEM_ROOT block sizes in sql_const.h
- Updated MALLOC_OVERHEAD to also take into account the extra memory
allocated by my_malloc()
- Updated init_alloc_root() to only take MALLOC_OVERHEAD into account as
buffer size, not MALLOC_OVERHEAD + sizeof(USED_MEM).
- Reset mem_root->first_block_usage if and only if first block was used.
- Increase MEM_ROOT buffers sized used by my_load_defaults, plugin_init,
Create_tmp_table, allocate_table_share, TABLE and TABLE_SHARE.
This decreases number of malloc calls during queries.
- Use a small buffer for THD->main_mem_root in THD::THD. This avoids
multiple malloc() call for new connections.
I tried the above changes on a complex select query with 12 tables.
The following shows the number of extra allocations that where used
to increase the size of the MEM_ROOT buffers.
Original code:
- Connection to MariaDB: 9 allocations
- First query run: 146 allocations
- Second query run: 24 allocations
Max memory allocated for thd when using with heap table: 61,262,408
Max memory allocated for thd when using Aria tmp table: 419,464
After changes:
Connection to MariaDB: 0 allocations
- First run: 25 allocations
- Second run: 7 allocations
Max memory allocated for thd when using with heap table: 61,347,424
Max memory allocated for thd when using Aria table: 529,168
The new code uses slightly more memory, but avoids memory fragmentation
and is slightly faster thanks to much fewer calls to malloc().
Reviewed-by: Sergei Golubchik <serg@mariadb.org>
Heap tables are allocated blocks to store rows according to
my_default_record_cache (mapped to the server global variable
read_buffer_size).
This causes performance issues when the record length is big
(> 1000 bytes) and the my_default_record_cache is small.
Changed to instead split the default heap allocation to 1/16 of the
allowed space and not use my_default_record_cache anymore when creating
the heap. The allocation is also aligned to be just under a power of 2.
For some test that I have been running, which was using record length=633,
the speed of the query doubled thanks to this change.
Other things:
- Fixed calculation of max_records passed to hp_create() to take
into account padding between records.
- Updated calculation of memory needed by heap tables. Before we
did not take into account internal structures needed to access rows.
- Changed block sized for memory_table from 1 to 16384 to get less
fragmentation. This also avoids a problem where we need 1K
to manage index and row storage which was not counted for before.
- Moved heap memory usage to a separate test for 32 bit.
- Allocate all data blocks in heap in powers of 2. Change reported
memory usage for heap to reflect this.
Reviewed-by: Sergei Golubchik <serg@mariadb.org>
When using the default innodb_log_buffer_size=2m, mariadb-backup --backup
would spend a lot of time re-reading and re-parsing the log. For reads,
it would be beneficial to memory-map the entire ib_logfile0 to the
address space (typically 48 bits or 256 TiB) and read it from there,
both during --backup and --prepare.
We will introduce the Boolean read-only parameter innodb_log_file_mmap
that will be OFF by default on most platforms, to avoid aggressive
read-ahead of the entire ib_logfile0 in when only a tiny portion would be
accessed. On Linux and FreeBSD the default is innodb_log_file_mmap=ON,
because those platforms define a specific mmap(2) option for enabling
such read-ahead and therefore it can be assumed that the default would
be on-demand paging. This parameter will only have impact on the initial
InnoDB startup and recovery. Any writes to the log will use regular I/O,
except when the ib_logfile0 is stored in a specially configured file system
that is backed by persistent memory (Linux "mount -o dax").
We also experimented with allowing writes of the ib_logfile0 via a
memory mapping and decided against it. A fundamental problem would be
unnecessary read-before-write in case of a major page fault, that is,
when a new, not yet cached, virtual memory page in the circular
ib_logfile0 is being written to. There appears to be no way to tell
the operating system that we do not care about the previous contents of
the page, or that the page fault handler should just zero it out.
Many references to HAVE_PMEM have been replaced with references to
HAVE_INNODB_MMAP.
The predicate log_sys.is_pmem() has been replaced with
log_sys.is_mmap() && !log_sys.is_opened().
Memory-mapped regular files differ from MAP_SYNC (PMEM) mappings in the
way that an open file handle to ib_logfile0 will be retained. In both
code paths, log_sys.is_mmap() will hold. Holding a file handle open will
allow log_t::clear_mmap() to disable the interface with fewer operations.
It should be noted that ever since
commit 685d958e38 (MDEV-14425)
most 64-bit Linux platforms on our CI platforms
(s390x a.k.a. IBM System Z being a notable exception) read and write
/dev/shm/*/ib_logfile0 via a memory mapping, pretending that it is
persistent memory (mount -o dax). So, the memory mapping based log
parsing that this change is enabling by default on Linux and FreeBSD
has already been extensively tested on Linux.
::log_mmap(): If a log cannot be opened as PMEM and the desired access
is read-only, try to open a read-only memory mapping.
xtrabackup_copy_mmap_snippet(), xtrabackup_copy_mmap_logfile():
Copy the InnoDB log in mariadb-backup --backup from a memory
mapped file.
Updated tests: cases with bugs or which cannot be run
with the cursor-protocol were excluded with
"--disable_cursor_protocol"/"--enable_cursor_protocol"
Fix for v.10.5
C/C 3.4 disables mysql_old_password by default, so
add an option for the `connect` command to support specifying
allowed authentication plugins (MARIADB_OPT_RESTRICTED_AUTH).
use it to enable mysql_old_password when needed for testing
Reset the connection_name to contain a null string, if the pointer
points to the same space as that of the system variable
default_master_connection.
We do this because the system variable may be updated which could free
the pointer and create a new one, causing use-after-free for
re-execution of prepared statements and stored procedures where the
LEX may be reused.
This allows connection_name to be set again be to the system variable
pointer in the next call of this function (see earlier in this
function), after any possible updates to the system variable.
When the system variables @@debug_dbug was assigned to
some expression, Sys_debug_dbug::do_check() did not properly
convert the value from the expression character set to utf8.
So the value was erroneously re-interpretted as utf8 without
conversion. In case of a tricky expression character set
(e.g. utf16le), this led to unexpected results.
Fix:
Re-using Sys_var_charptr::do_string_check() in Sys_debug_dbug::do_check().
In commit 24648768b4 (MDEV-30136)
the parameter innodb_flush_method was deprecated, with no direct
replacement for innodb_flush_method=O_DIRECT_NO_FSYNC.
Let us change innodb_doublewrite from Boolean to ENUM that can
be changed while the server is running:
OFF: Assume that writes of innodb_page_size are atomic
ON: Prevent torn writes (the default)
fast: Like ON, but avoid synchronizing writes to data files
The deprecated start-up parameter innodb_flush_method=NO_FSYNC will cause
innodb_doublewrite=ON to be changed to innodb_doublewrite=fast,
which will prevent InnoDB from making any durable writes to data files.
This would normally be done right before the log checkpoint LSN is updated.
Depending on the file systems being used and their configuration,
this may or may not be safe.
The value innodb_doublewrite=fast differs from the previous combination of
innodb_doublewrite=ON and innodb_flush_method=O_DIRECT_NO_FSYNC by always
invoking os_file_flush() on the doublewrite buffer itself
in buf_dblwr_t::flush_buffered_writes_completed(). This should be safer
when there are multiple doublewrite batches between checkpoints.
Typically, once per second, buf_flush_page_cleaner() would write out
up to innodb_io_capacity pages and advance the log checkpoint.
Also typically, innodb_io_capacity>128, which is the size of the
doublewrite buffer in pages. Should os_file_flush_func() not be invoked
between doublewrite batches, writes could be reordered in an unsafe way.
The setting innodb_doublewrite=fast could be safe when the doublewrite
buffer (the first file of the system tablespace) and the data files
reside in the same file system.
This was tested by running "./mtr --rr innodb.alter_kill". On the first
server startup, with innodb_doublewrite=fast, os_file_flush_func()
would only be invoked on the ibdata1 file and possibly ib_logfile0.
On subsequent startups with innodb_doublewrite=OFF, os_file_flush_func()
will be invoked on the individual data files during log_checkpoint().
Note: The setting debug_no_sync (in the code, my_disable_sync) would
disable all durable writes to InnoDB files, which would be much less safe.
IORequest::Type: Introduce special values WRITE_DBL and PUNCH_DBL
for asynchronous writes that are submitted via the doublewrite buffer.
In this way, fil_space_t::use_doublewrite() or buf_dblwr.in_use()
will only be consulted during buf_page_t::flush() and the doublewrite
buffer can be enabled or disabled without any fear of inconsistency.
buf_dblwr_t::block_size: Replaces block_size().
buf_dblwr_t::flush_buffered_writes(): If !in_use() and the doublewrite
buffer is empty, just invoke fil_flush_file_spaces() and return. The
doublewrite buffer could have been disabled while a batch was in
progress.
innodb_init_params(): If innodb_flush_method=O_DIRECT_NO_FSYNC,
set innodb_doublewrite=fast or innodb_doublewrite=fearless.
Thanks to Mark Callaghan for reporting this, and Vladislav Vaintroub
for feedback.
binlog_space_limit is a variable in Percona server used to limit the total
size of all binary logs.
This implementation is based on code from Percona server 5.7.
In MariaDB we decided to call the variable max-binlog-total-size to be
similar to max-binlog-size. This makes it easier to find in the output
from 'mariadbd --help --verbose'). MariaDB will also support
binlog_space_limit for compatibility with Percona.
Some internal notes to explain implementation notes:
- When running MariaDB does not delete binary logs that are either
used by slaves or have active xid that are not yet committed.
Some implementation notes:
- max-binlog-total-size is by default 0 (no limit).
- max-binlog-total-size can be changed without server restart.
- Binlog file sizes are checked on startup, or if
max-binlog-total-size is set to a value > 0, not for every log write.
The total size of all binary logs is cached and dynamically updated
when updating the binary log on binary log rotation.
- max-binlog-total-size is checked against existing log files during
serverstart, binlog rotation, FLUSH LOGS, when writing to binary log
or when max-binlog-total-size changes value.
- Option --slave-connections-needed-for-purge with 1 as default added.
This allows one to ensure that we do not delete binary logs if there
is less than 'slave-connections-needed-for-purge' connected.
Without this option max-binlog-total-size would potentially delete
binlogs needed by slaves on server startup or when a slave disconnects
as there are then no connected slaves to protect active binlogs.
- PURGE BINARY LOGS TO ... will be executed as if
slave-connectitons-needed-for-purge would be zero. In other words
it will do the purge even if there is no slaves connected. If there
are connected slaves working on the logs, these will be protected.
- If binary log is on and max-binlog-total_size <> 0 then the status
variable 'Binlog_disk_use' shows the current size of all old binary
logs + the state of the current one.
- Removed test of strcmp(log_file_name, log_info.log_file_name) in
purge_logs_before_date() as this is tested in can_purge_logs()
- To avoid expensive calls of log_in_use() we cache the result for the
last log that is in use by a slave. Future calls to can_purge_logs()
for this binary log will be quickly detected and false will be returned
until a slave starts working on a new log.
- Note that after a binary log rotation caused by max_binlog_size,
the last log will not be purged directly as it is still in use
internally. The next binary log write will purge binlogs if needed.
Reviewer:Kristian Nielsen <knielsen@knielsen-hq.org>
not default_mysqld.cnf. The latter has only server settings,
it misses mtr-specific client configuration
Except for spider, that doesn't use mysqld.1 server
and default_my.cnf starts it automatically.
Spider tests have to include both default_mysqld.cnf and
default_client.cnf
Reason:
======
undo_space_dblwr test case fails if the first page of undo
tablespace is not flushed before restart the server. While
restarting the server, InnoDB fails to detect the first
page of undo tablespace from doublewrite buffer.
Fix:
===
Use "ib_log_checkpoint_avoid_hard" debug sync point
to avoid checkpoint and make sure to flush the
dirtied page before killing the server.
innodb_make_page_dirty(): Fails to set
srv_fil_make_page_dirty_debug variable.
