Hello,

innodb_use_mtflush is deprecated / removed.

"Description: Whether to enable multi-threaded flush. See Fusion-io Multi-threaded Flush. Removed in MariaDB 10.3.2, use innodb-page-cleaners instead. "

[innpdb_use_mtflush|
https://mariadb.com/kb/en/library/xtradbinnodb-server-system-variables/#innodb_use_mtflush]

Marko Mäkela:

"
In my opinion, the XtraDB 5.6 multi-threaded flushing is a dead end, and the InnoDB 5.7
multiple page_cleaner threads serve a similar purpose.
For what it is worth, innodb_use_mtflush was removed from MariaDB 10.3.2 in MDEV-12496."

But on this page in the section "Multi-threaded flush"
https://mariadb.com/kb/en/library/compression/

it will be still recommended

I left a note in this section.

"Please note that innodb-mtflush-threads is deprecated in 10.2.9 and removed in 10.3.2 .
Please use innodb_page_cleaners instead."

But this section should be rewritten with help of a core developer.