Finding temporary table name in MariaDB

Question

As I reported some days ago to MariaDB bug tracker the following bug: https://jira.mariadb.org/browse/MDEV-17420, slave replicas with version 10.2.x are leaking temporary tables on MyISAM files.

Our temp directory is filling with .MYD/.MYI files up to the point that the process file descriptor limit is reached, for example:

-rw-rw---- 1 mysql mysql    1024 Oct 24 13:25 #sql324a_1a28c_e4b18.MYI
-rw-rw---- 1 mysql mysql       0 Oct 24 13:25 #sql324a_1a28c_e4b18.MYD
-rw-rw---- 1 mysql mysql    1024 Oct 24 13:25 #sql324a_1a28c_e4b19.MYI
-rw-rw---- 1 mysql mysql       0 Oct 24 13:25 #sql324a_1a28c_e4b19.MYD
-rw-rw---- 1 mysql mysql  189376 Oct 24 13:25 #sql324a_1a28c_e4b0c.MYD
-rw-rw---- 1 mysql mysql    5120 Oct 24 13:26 #sql324a_1a28c_e4b58.MYI
-rw-rw---- 1 mysql mysql    3575 Oct 24 13:26 #sql324a_1a28c_e4b58.MYD
-rw-rw---- 1 mysql mysql    1024 Oct 24 13:26 #sql324a_1a28c_e4b59.MYI
-rw-rw---- 1 mysql mysql       0 Oct 24 13:26 #sql324a_1a28c_e4b59.MYD
-rw-rw---- 1 mysql mysql    1024 Oct 24 13:27 #sql324a_1a28c_e4b6e.MYI
-rw-rw---- 1 mysql mysql    1204 Oct 24 13:27 #sql324a_1a28c_e4b6e.MYD
-rw-rw---- 1 mysql mysql 1256372 Oct 24 13:28 #sql324a_1a28c_e4ae3.MYD

After that, the only solution is to stop the mysqld process and then start it again.

Of courdse, we have checked on the master and these same files are not leaked or stale.

The question: does anyone know how to find some information of these temporary tables (at least their names) to help in debugging this case with more detail?

Thanks

Answer 1

I ask about the PROCESSLIST in hopes of discovering whether only certain types of queries cause the leaked tmp table. Knowing that might expedite finding a solution.

Based on a recent comment in the bug report, it sounds like a cron job doing this might be a workaround (but apparently not):

STOP SLAVE;
START SLAVE;