ClickHouse: Too many open files while using materialized view with kafka source

Greetings. I have Ubuntu 18.04 source system. Clickhouse server version - 18.12.17. Default config. Database structure creation:

create table a (EventDate Date) ENGINE MergeTree() partition by toYYYYMM(EventDate) order by (EventDate) settings index_granularity=8192;

create table k (EventDate Date) ENGINE=Kafka SETTINGS
  kafka_broker_list = 'localhost:9092,localhost:9093,localhost:9094',
  kafka_topic_list = 'a',
  kafka_group_name = 'group1',
  kafka_format = 'JSONEachRow';

create materialized view w to a as select * from k;

As soon, as materialized view was created, amount of file descriptors for clickhouse server process starts to grow each second to the limit of max open files. Error logs are empty. Usual log contains only debug ant trace info. However syslog contains following errors:

Sep 22 18:22:38 kernel: [25449.716131] netlink: 'TCPHandler': attribute type 1 has an invalid length.
Sep 22 18:22:38 kernel: [25449.729949] netlink: 'TCPHandler': attribute type 1 has an invalid length.
Sep 22 18:22:40 kernel: [25451.228134] netlink: 'ParalInputsProc': attribute type 1 has an invalid length.
Sep 22 18:22:40 kernel: [25451.228175] netlink: 'ParalInputsProc': attribute type 1 has an invalid length.
Sep 22 18:22:42 kernel: [25453.227433] netlink: 'ParalInputsProc': attribute type 1 has an invalid length.

Am I missing something? Any help would be much appreciated.