create database test_zoo;

-- Let's create 5000 tables
for i in `seq 5000`; do echo -n $i ""; \
   clickhouse-client -q "CREATE TABLE if not exists test_zoo.test$i  (d DATE, p UInt64, s String) ENGINE = ReplicatedMergeTree ('/clickhouse/{cluster}/tables/{shard}/{table}','{replica}') PARTITION BY d ORDER BY p";
done;

ZK CPU utilization 30% of one CPU core

--Let's insert 101 inserts into each table to fill ZK recent 100 blocks 
for i in `seq 5000`; do echo -n $i "";    for j in `seq 101`; do clickhouse-client -q "insert into test_zoo.test$i select today(), $j, ''"; done; done;

ZK CPU utilization 30% of one CPU core


cleanup_delay_period = 300 / merge_selecting_sleep_ms = 50000   
restart
ZK CPU utilization <10% of one CPU core