With this version of MariaDB I got a lot of DeadLock :/ Once or twice daily.
interesting might want to keep an eye on 10.1.20 affected bugs Issue Navigator - JIRA 10.1.21 fixed bugs Issue Navigator - JIRA
For XenForo? Try my Deadlock Avoidance add-on. It really helps on my sites XenForo has some design issues which cause it to deadlock often under load depending on how the optimizer picks rows/indexes to lock. My deadlock avoidance add-on re-orders some things and pulls bulky operations out of transactions which virtually eliminates these errors. It requires php5.5+, which is why XenForo can't implement my solutions since XenForo still supports php 5.3