Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.5.7, 10.5.8
Description
If buf_flush_ahead() happens to be executed immediately before a server shutdown is initiated, and if innodb_flush_sync=0 (nondefault setting), then the shutdown may hang because the page cleaner thread fails to finish its job. The following patch demonstrates and fixes this:
diff --git a/mysql-test/suite/innodb/r/autoinc_debug.result b/mysql-test/suite/innodb/r/autoinc_debug.result
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index 5856c75f784..8ff8f41289a 100644
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--- a/mysql-test/suite/innodb/r/autoinc_debug.result
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+++ b/mysql-test/suite/innodb/r/autoinc_debug.result
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@@ -1,6 +1,9 @@
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CREATE TABLE t1 (id INT AUTO_INCREMENT PRIMARY KEY)ENGINE=INNODB;
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# SETTING auto_increment_increment IN CONNECTION DEFAULT
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SET AUTO_INCREMENT_INCREMENT = 1;
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+SET GLOBAL innodb_flush_sync=OFF;
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+CREATE TEMPORARY TABLE t (id SERIAL) ENGINE=InnoDB;
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+SET debug_dbug= '+d,ib_log_flush_ahead';
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INSERT INTO t1 VALUES(NULL);
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SELECT * FROM t1;
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id
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diff --git a/mysql-test/suite/innodb/t/autoinc_debug.test b/mysql-test/suite/innodb/t/autoinc_debug.test
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index 2e662565490..3c78d9ecd01 100644
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--- a/mysql-test/suite/innodb/t/autoinc_debug.test
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+++ b/mysql-test/suite/innodb/t/autoinc_debug.test
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@@ -8,6 +8,9 @@ CREATE TABLE t1 (id INT AUTO_INCREMENT PRIMARY KEY)ENGINE=INNODB;
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--echo # SETTING auto_increment_increment IN CONNECTION DEFAULT
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SET AUTO_INCREMENT_INCREMENT = 1;
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+SET GLOBAL innodb_flush_sync=OFF;
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+CREATE TEMPORARY TABLE t (id SERIAL) ENGINE=InnoDB;
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+SET debug_dbug= '+d,ib_log_flush_ahead';
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INSERT INTO t1 VALUES(NULL);
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SELECT * FROM t1;
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SHOW CREATE TABLE t1;
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diff --git a/storage/innobase/buf/buf0flu.cc b/storage/innobase/buf/buf0flu.cc
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index d1a55bae456..bdb1f3404a1 100644
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--- a/storage/innobase/buf/buf0flu.cc
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+++ b/storage/innobase/buf/buf0flu.cc
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@@ -2104,6 +2104,7 @@ static os_thread_ret_t DECLARE_THREAD(buf_flush_page_cleaner)(void*)
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if (!dirty_blocks)
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{
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+unemployed2:
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if (UNIV_UNLIKELY(lsn_limit != 0))
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{
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buf_flush_sync_lsn= 0;
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@@ -2126,6 +2127,13 @@ static os_thread_ret_t DECLARE_THREAD(buf_flush_page_cleaner)(void*)
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const lsn_t oldest_lsn= buf_pool.get_oldest_modification(0);
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+#if 0 /* MDEV-12227 FIXME: enable this */
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+ ut_ad(oldest_lsn); /* dirty_blocks implies this */
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+#else
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+ if (!oldest_lsn)
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+ goto unemployed2;
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+#endif
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+
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if (UNIV_UNLIKELY(lsn_limit != 0) && oldest_lsn >= lsn_limit)
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buf_flush_sync_lsn= 0;
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diff --git a/storage/innobase/mtr/mtr0mtr.cc b/storage/innobase/mtr/mtr0mtr.cc
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index 4c22f05c4ba..60c91364b15 100644
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--- a/storage/innobase/mtr/mtr0mtr.cc
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+++ b/storage/innobase/mtr/mtr0mtr.cc
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@@ -889,6 +889,7 @@ inline std::pair<lsn_t,bool> mtr_t::finish_write(ulint len)
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m_log.for_each_block(write_log);
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m_commit_lsn = log_sys.get_lsn();
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bool flush = log_close(m_commit_lsn);
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+ DBUG_EXECUTE_IF("ib_log_flush_ahead", flush=true;);
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return std::make_pair(start_lsn, flush);
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} |
If I omit the fix to the file buf0flu.cc, the test would hang for me on a box where nproc reports 40:
./mtr --parallel=auto --repeat=100 innodb.autoinc_debug{,,,,,,,,,,,,,,,,,,,,,,}
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On the first attempt, 22 of the 23 concurrent runs hung on the first pass. The last worker hung on the 22nd pass. With the fix, all 23×100 runs completed successfully.
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