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PS-10595 [8.4]: combined lazy latch init + rw_lock_list bulk registration
https://perconadev.atlassian.net/browse/PS-10595 Combines two buffer-pool initialization speedups: 1. Reduce rw_lock_list contention during buffer pool initialization by registering block rw-locks in bulk via an O(1) list splice under rw_lock_list_mutex instead of taking it once per block. 2. Lazy per-block latch initialization - defer creation of each block's mutex and rw-locks until the block is first used. The second optimization is deferring the cost (paid later in runtime). Therefore it is disabled by default and a new sysvar has to be used to enable it: innodb_buffer_pool_lazy_latch_init. While it is disabled, the first optimization helps a little bit. These changes are based on a contribution we got from: Alexey Bychko <abychko@gmail.com>
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Lines changed: 621 additions & 97 deletions

‎mysql-test/r/all_persisted_variables.result‎

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@@ -47,7 +47,7 @@ include/assert.inc [Expect 500+ variables in the table. Due to open Bugs, we are
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# Test SET PERSIST
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include/assert.inc [Expect 491 persisted variables in the table.]
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include/assert.inc [Expect 492 persisted variables in the table.]
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************************************************************
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* 3. Restart server, it must preserve the persisted variable

‎mysql-test/suite/innodb/r/buffer_pool_lazy_latch_init.result‎

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SELECT @@global.innodb_buffer_pool_lazy_latch_init;
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@@global.innodb_buffer_pool_lazy_latch_init
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1
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# Scan I_S.INNODB_BUFFER_PAGE while the pool is mostly unused.
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# Without the lazy-init guard this enters an unconstructed mutex.
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page
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WHERE page_state = 'NOT_USED' AND page_type = 'UNKNOWN';
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ok
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1
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# Fault index/data pages into the pool.
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CREATE TABLE t1 (id INT PRIMARY KEY, val INT) ENGINE=InnoDB;
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# Some INDEX pages are now cached.
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page
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WHERE page_type = 'INDEX';
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ok
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1
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# Create compressed pages, evict their uncompressed frames, then scan
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# I_S.INNODB_BUFFER_PAGE_LRU for standalone compressed descriptors.
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CREATE TABLE t_zip (
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id INT PRIMARY KEY,
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val BLOB,
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KEY(val(10))
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) ENGINE=InnoDB ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=1;
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SELECT COUNT(*) FROM t_zip;
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COUNT(*)
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100
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page_lru;
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ok
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1
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# Expand the buffer pool (new lazy chunks), then re-scan.
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SET GLOBAL innodb_buffer_pool_size = 25165824;
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page;
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ok
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1
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# Shrink the buffer pool (chunks freed), then re-scan.
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SET GLOBAL innodb_buffer_pool_size = 8388608;
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page;
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ok
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# Restart: the pool comes back up in lazy mode (opt reapplied).
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# restart
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SELECT @@global.innodb_buffer_pool_lazy_latch_init;
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@@global.innodb_buffer_pool_lazy_latch_init
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1
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page;
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ok
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1
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SELECT COUNT(*) FROM t1;
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COUNT(*)
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2000
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DROP TABLE t1, t_zip;

‎mysql-test/suite/innodb/t/buffer_pool_lazy_latch_init-master.opt‎

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--innodb-buffer-pool-lazy-latch-init=ON --innodb-buffer-pool-size=16M --innodb-buffer-pool-chunk-size=2M

‎mysql-test/suite/innodb/t/buffer_pool_lazy_latch_init.test‎

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#
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# PS-10595: exercise innodb_buffer_pool_lazy_latch_init=ON end to end.
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#
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# With lazy latch init, a never-used buffer block has no constructed latches.
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# This test drives the paths that touch every chunk block regardless of state:
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# - INFORMATION_SCHEMA.INNODB_BUFFER_PAGE scans all blocks (including unused
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# ones) - it must report unused blocks as free without entering their
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# (unconstructed) mutex,
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# - online buffer pool resize creates fresh lazy chunks and later frees them,
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# - a restart brings the pool back up in lazy mode.
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# On a debug build this also activates all the block->latches_initialized
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# assertions added by this feature.
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#
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--source include/have_innodb_max_16k.inc
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# The feature is opt-in and read only; confirm the server started with it ON.
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SELECT @@global.innodb_buffer_pool_lazy_latch_init;
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let $wait_timeout = 180;
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let $wait_condition =
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SELECT SUBSTR(variable_value, 1, 34) = 'Completed resizing buffer pool at '
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FROM performance_schema.global_status
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WHERE LOWER(variable_name) = 'innodb_buffer_pool_resize_status';
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--echo # Scan I_S.INNODB_BUFFER_PAGE while the pool is mostly unused.
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--echo # Without the lazy-init guard this enters an unconstructed mutex.
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page
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WHERE page_state = 'NOT_USED' AND page_type = 'UNKNOWN';
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--echo # Fault index/data pages into the pool.
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CREATE TABLE t1 (id INT PRIMARY KEY, val INT) ENGINE=InnoDB;
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--disable_query_log
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BEGIN;
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let $i = 2000;
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while ($i) {
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eval INSERT INTO t1 VALUES ($i, $i);
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dec $i;
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}
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COMMIT;
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--enable_query_log
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--echo # Some INDEX pages are now cached.
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page
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WHERE page_type = 'INDEX';
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--echo # Create compressed pages, evict their uncompressed frames, then scan
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--echo # I_S.INNODB_BUFFER_PAGE_LRU for standalone compressed descriptors.
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CREATE TABLE t_zip (
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id INT PRIMARY KEY,
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val BLOB,
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KEY(val(10))
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) ENGINE=InnoDB ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=1;
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--disable_query_log
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BEGIN;
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let $i = 100;
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while ($i) {
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eval INSERT INTO t_zip VALUES ($i, REPEAT('a', 2000));
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dec $i;
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}
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COMMIT;
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--enable_query_log
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SELECT COUNT(*) FROM t_zip;
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let $have_debug = `SELECT VERSION() LIKE '%debug%'`;
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if ($have_debug) {
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--disable_query_log
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SET GLOBAL innodb_buffer_pool_evict = 'uncompressed';
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--enable_query_log
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let $compressed_only_pages = `SELECT COUNT(*)
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FROM information_schema.innodb_buffer_page_lru
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WHERE table_name LIKE '%t_zip%' AND compressed = 'YES'`;
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if (!$compressed_only_pages) {
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--die Expected standalone compressed descriptors for t_zip
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}
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}
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page_lru;
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--echo # Expand the buffer pool (new lazy chunks), then re-scan.
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SET GLOBAL innodb_buffer_pool_size = 25165824;
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--source include/wait_condition.inc
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page;
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--echo # Shrink the buffer pool (chunks freed), then re-scan.
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SET GLOBAL innodb_buffer_pool_size = 8388608;
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--source include/wait_condition.inc
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page;
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--echo # Restart: the pool comes back up in lazy mode (opt reapplied).
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--source include/restart_mysqld.inc
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SELECT @@global.innodb_buffer_pool_lazy_latch_init;
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SELECT COUNT(*) > 0 AS ok FROM information_schema.innodb_buffer_page;
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SELECT COUNT(*) FROM t1;
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DROP TABLE t1, t_zip;

‎mysql-test/suite/sys_vars/r/innodb_buffer_pool_lazy_latch_init_basic.result‎

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SELECT @@global.innodb_buffer_pool_lazy_latch_init;
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@@global.innodb_buffer_pool_lazy_latch_init
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0
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SET @@global.innodb_buffer_pool_lazy_latch_init = ON;
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ERROR HY000: Variable 'innodb_buffer_pool_lazy_latch_init' is a read only variable
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SET @@global.innodb_buffer_pool_lazy_latch_init = OFF;
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ERROR HY000: Variable 'innodb_buffer_pool_lazy_latch_init' is a read only variable
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SELECT @@session.innodb_buffer_pool_lazy_latch_init;
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ERROR HY000: Variable 'innodb_buffer_pool_lazy_latch_init' is a GLOBAL variable

‎mysql-test/suite/sys_vars/t/innodb_buffer_pool_lazy_latch_init_basic.test‎

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#
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# Basic test for innodb_buffer_pool_lazy_latch_init
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#
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# It is a read-only, global-only boolean that defaults to OFF.
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#
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# Check the default value.
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SELECT @@global.innodb_buffer_pool_lazy_latch_init;
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# It is read only: it cannot be changed at runtime.
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--error ER_INCORRECT_GLOBAL_LOCAL_VAR
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SET @@global.innodb_buffer_pool_lazy_latch_init = ON;
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--error ER_INCORRECT_GLOBAL_LOCAL_VAR
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SET @@global.innodb_buffer_pool_lazy_latch_init = OFF;
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# It has only a global scope.
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--error ER_INCORRECT_GLOBAL_LOCAL_VAR
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SELECT @@session.innodb_buffer_pool_lazy_latch_init;

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