Mysqldump 2-3 times slower since MariaDB upgrade to 10.1.29

We upgraded 2 of our production database servers to 10.1.29 (from 10.1.15). We also updated some other yum packages at the same time. After the upgrade, the nightly mysqldump backup time has increased from around 4 hours and 15 minutes to 14 hours and 40 minutes (3 times increase) on our first database server and from 6 hours and 30 minutes to 13 hours and 40 minutes (2 times increase) on our second database server.

Normal database performance (sql query times) was not visibly impacted.

We use the following command for our mysqldumps:

echo 'show databases' | /usr/bin/mysql --defaults-extra-file=<file> | grep -v -f <file> | while read DB; do

  /usr/bin/mysqldump --defaults-extra-file=<file> --routines --events $DB > <file>.sql