Cannot allocate block number in ZooKeeper: Coordination::Exception: Connection loss

When I write data into my clickhouse using jdbc for 1000 0000 records, it throws an exception.

And I find my zookeeper is still alive. Could anyone tell me why the connection is lost. Thank u.

i: 6999998
i: 6999999
i: 7000000
Wed Jul 07 17:25:40 CST 2021
ru.yandex.clickhouse.except.ClickHouseException: ClickHouse exception, code: 999, host: 10.10.1.1, port: 8123; Code: 999, e.displayText() = DB::Exception: Cannot allocate block number in ZooKeeper: Coordination::Exception: Connection loss (version 21.6.3.14 (official build))

        at ru.yandex.clickhouse.except.ClickHouseExceptionSpecifier.specify(ClickHouseExceptionSpecifier.java:59)
        at ru.yandex.clickhouse.except.ClickHouseExceptionSpecifier.specify(ClickHouseExceptionSpecifier.java:29)
        at ru.yandex.clickhouse.ClickHouseStatementImpl.checkForErrorAndThrow(ClickHouseStatementImpl.java:1094)
        at ru.yandex.clickhouse.ClickHouseStatementImpl.sendStream(ClickHouseStatementImpl.java:1061)
        at ru.yandex.clickhouse.ClickHouseStatementImpl.sendStream(ClickHouseStatementImpl.java:1026)
        at ru.yandex.clickhouse.ClickHouseStatementImpl.sendStream(ClickHouseStatementImpl.java:1019)
        at ru.yandex.clickhouse.ClickHousePreparedStatementImpl.executeBatch(ClickHousePreparedStatementImpl.java:381)
        at ru.yandex.clickhouse.ClickHousePreparedStatementImpl.executeBatch(ClickHousePreparedStatementImpl.java:364)
        at com.chris.slient.clickhouse.App.test11(App.java:304)
        at com.chris.slient.clickhouse.App.main(App.java:441)
Caused by: java.lang.Throwable: Code: 999, e.displayText() = DB::Exception: Cannot allocate block number in ZooKeeper: Coordination::Exception: Connection loss (version 21.6.3.14 (official build))

        at ru.yandex.clickhouse.except.ClickHouseExceptionSpecifier.specify(ClickHouseExceptionSpecifier.java:54)
        ... 9 more