Errors running mysqldump related to LOCK TABLES

If you see such error patterns when running mysqldump backup:

# mysqldump -u wordpress_u -p wordpress_db > ./tmp/db_backups/wordpress_db-`date +'%Y%m%d%H%M'`.sql

Enter password:
mysqldump: Got error: 1016: Can’t open file: ‘./wordpress_db/wp_1050_postmeta.frm’ (errno: 24) when using LOCK TABLES

# mysqldump -u wordpress_u -p wordpress_db > ./tmp/db_backups/wordpress_db-`date +'%Y%m%d%H%M'`.sql

Enter password:
mysqldump: Got error: 23: Out of resources when opening file ‘./wordpress_db/wp_1050_options.MYD’ (Errcode: 24) when using LOCK TABLES

try to add –lock-tables=false to dump command.