Details
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Bug
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Status: Closed (View Workflow)
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Critical
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Resolution: Fixed
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10.5, 10.6, 10.7(EOL)
Description
The mariabackup --prepare shows this warning:
2021-10-07 1:13:23 0 [Note] InnoDB: Starting a batch to recover 9962 pages from redo log.
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2021-10-07 1:13:28 0 [Warning] InnoDB: Difficult to find free blocks in the buffer pool (21 search iterations)! 21 failed attempts to flush a page! Consider increasing innodb_buffer_pool_size. Pending flushes (fsync) log: 0; buffer pool: 0. 582296 OS file reads, 504266 OS file writes, 2396 OS fsyncs.
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The error is similar to:
https://jira.mariadb.org/browse/MDEV-20679
https://jira.mariadb.org/browse/MDEV-19176
But looks like they are already fixed in 10.5.1
Attachments
Issue Links
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Activity
I diagnosed this with thiru today. Similar to MDEV-27461, the buffer pool is filled with modified pages, which will not be written out because the page cleaner is in untimed sleep (MDEV-24278).
We agreed on a fix that buf_flush_LRU_list_batch() should disregard the 256-page minimum length of buf_pool.LRU (BUF_LRU_MIN_LEN) during recovery, and simply initiate writes of all dirty pages whenever a page needs to be allocated. In the hang that thiru reproduced, the length of buf_pool.LRU was 215 pages.
That fix is OK to push, along with the regression test case that reproduces the issue.
The Innodb.recovery_memory test fails constantly in bb-11.0 with:
CURRENT_TEST: innodb.recovery_memory
mysqltest: In included file "./include/wait_until_connected_again.inc":
included from ./include/start_mysqld.inc at line 49:
included from ./include/restart_mysqld.inc at line 11:
included from /home/my/maria-11.0-org/mysql-test/suite/innodb/t/recovery_memory.test at line 21:
At line 40: Server failed to restart
I assume most developers has not noticed this as this is marked as 'big'.
monty, I think that your observation needs to be considered in the scope of the follow-up fix MDEV-30551 that thiru is currently working on.
Issue present in 10.7 trunk
10.7.1 5cc9cf9a05582307abefd8f3b57548945da86b1a (Debug)
2021-10-09 13:18:55 0 [Warning] InnoDB: Difficult to find free blocks in the buffer pool (21 search iterations)! 21 failed attempts to flush a page! Consider increasing innodb_buffer_pool_size. Pending flushes (fsync) log: 0; buffer pool: 0. 149 OS file reads, 2 OS file writes, 2 OS fsyncs.