For years we are using a master - slave parallel replication setup which always worked fine.
We were using previously v10.1, v10.4 and v10.6 of mariadb and never witnessed the issue.

However since upgrading to v10.11.2 the parallel replication process gets "stuck" every few days.
When this happens, the only solution is to `kill -9` the mariadb process.

We have 2 replicas, one which runs continuously without being interrupted, and that one doesn't have the issue.
The other one however we use for making daily backups. So we stop mariadb at midnight, then make the backup (which takes about 7 - 8 hours to complete) and then start mariadb again.
Of course this means that this server has to catch up with several hours worth of binlogs, which is what seems to trigger the deadlock.

This is the output of "show slave status":

https://dpaste.org/5axfT

This is the output of "show processlist":

https://dpaste.org/Ub10M

This is the output of "show engine innodb status":

https://dpaste.org/KmP1b

The full backtrace of all mariadb threads is attached as a txt file to this ticket.

These are my relevant mariadb settings:

slave_parallel_threads = 16
slave_parallel_mode = optimistic
innodb_compression_default = ON

I spoke to montywi and knielsen on #maria on liberachat about this and they recommended me to file a jira ticket here.