Threads are always in 'cleaning up' state in innodb status

MariaDB [test]> show processlist;

+----+------+-----------+-------+---------+------+-------+------------------+----------+

| Id | User | Host      | db    | Command | Time | State | Info             | Progress |

+----+------+-----------+-------+---------+------+-------+------------------+----------+

|  2 | root | localhost | test  | Query   |    0 | init  | show processlist |    0.000 |

|  3 | root | localhost | mysql | Sleep   |    4 |       | NULL             |    0.000 |

|  4 | root | localhost | test  | Sleep   |   10 |       | NULL             |    0.000 |

+----+------+-----------+-------+---------+------+-------+------------------+----------+

------------

TRANSACTIONS

------------

Trx id counter 2822

Purge done for trx's n:o < 0 undo n:o < 0 state: running but idle

History list length 0

LIST OF TRANSACTIONS FOR EACH SESSION:

---TRANSACTION 0, not started

MySQL thread id 3, OS thread handle 0x7f5a704ca700, query id 56 localhost root cleaning up

---TRANSACTION 0, not started

MySQL thread id 4, OS thread handle 0x7f5a70481700, query id 22 localhost root cleaning up

---TRANSACTION 2821, not started

MySQL thread id 2, OS thread handle 0x7f5a70513700, query id 58 localhost root init

show engine innodb status