I am trying to iterate two Resultsets from two connections simultaneously trying to merge two tables. This is how I get connection:

public static void execMany(Consumer<Connection> cons) {
    // ClickHouse server URL
    String url = "jdbc:clickhouse://myip:8123/db2";
    ClickHouseProperties properties = new ClickHouseProperties();
    properties.setSocketTimeout(6000000);
    properties.setSessionTimeout(6000000L);
    properties.setDatabase("db2");
    properties.setUser("default");
    properties.setPassword("12345");
    ClickHouseDataSource dataSource = new ClickHouseDataSource(url, properties);
    try (ClickHouseConnection connection = dataSource.getConnection()) {
        cons.accept(connection);
    } catch (SQLException e) {
        e.printStackTrace();
    }
}

This is how I iterate:

        var ref = new Object() {
            long txCnt = 0;
            long addrCnt = 0;
        };
        var cnt = ClickHouse.count("transactions_tmp2");
        ClickHouse.execMany(conn -> ClickHouse.execMany(conn1 -> {
            try {
                var select1 = conn.createStatement().executeQuery("SELECT * FROM %s order by %s".formatted(t1,f1));
                var select2 = conn1.createStatement().executeQuery("SELECT * FROM %s order by %s".formatted(t2,f2));
                String val2 = null;
                String val1 = null;
                while (true) {
                    if (ref.txCnt % 1000000 == 0)
                        System.out.println((ref.txCnt) + "/" + cnt + "=" + (1. * ref.txCnt / +cnt) + " addrCnt=" + ref.addrCnt + " fromAddress=" + val2 + " txAddress=" + val1);
                    if (val2 == null) {
                        if (!select2.next()) break;
                        ref.addrCnt++;
                        val2 = select2.getString(f2);
                    }
                    if (val1 == null) {
                        if (!select1.next()) break;
                        ref.txCnt++;
                        val1 = select1.getString(f1);
                    }
                    if (val1.compareTo(val2) < 0) {
                        val1 = null;
                        continue;
                    }
                    if (val2.compareTo(val1) < 0) {
                        val2 = null;
                        continue;
                    }
                    assert val1.equals(val2);
                    cons.accept(select1,select2);
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }));
    }

But suddenly I started getting this error, which I had never seen before:

Exception in thread "main" java.lang.RuntimeException: java.sql.SQLException: org.apache.http.MalformedChunkCodingException: Unexpected content at the end of chunk
    at me.nanosecond.TxImporter.lambda$merge$1(TxImporter.java:123)
    at me.nanosecond.ClickHouse.execMany(ClickHouse.java:291)
    at me.nanosecond.TxImporter.lambda$merge$2(TxImporter.java:78)
    at me.nanosecond.ClickHouse.execMany(ClickHouse.java:291)
    at me.nanosecond.TxImporter.merge(TxImporter.java:78)
    at me.nanosecond.TxImporter.main(TxImporter.java:185)
Caused by: java.sql.SQLException: org.apache.http.MalformedChunkCodingException: Unexpected content at the end of chunk
    at ru.yandex.clickhouse.response.ClickHouseResultSet.hasNext(ClickHouseResultSet.java:164)
    at ru.yandex.clickhouse.response.ClickHouseResultSet.next(ClickHouseResultSet.java:200)
    at me.nanosecond.TxImporter.lambda$merge$1(TxImporter.java:90)
    ... 5 more
Caused by: org.apache.http.MalformedChunkCodingException: Unexpected content at the end of chunk
    at org.apache.http.impl.io.ChunkedInputStream.getChunkSize(ChunkedInputStream.java:254)
    at org.apache.http.impl.io.ChunkedInputStream.nextChunk(ChunkedInputStream.java:222)
    at org.apache.http.impl.io.ChunkedInputStream.read(ChunkedInputStream.java:183)
    at org.apache.http.conn.EofSensorInputStream.read(EofSensorInputStream.java:135)
    at java.base/java.io.DataInputStream.read(DataInputStream.java:158)
    at ru.yandex.clickhouse.util.Utils.readFully(Utils.java:163)
    at ru.yandex.clickhouse.util.Utils.readFully(Utils.java:147)
    at ru.yandex.clickhouse.response.ClickHouseLZ4Stream.readNextBlock(ClickHouseLZ4Stream.java:102)
    at ru.yandex.clickhouse.response.ClickHouseLZ4Stream.checkNext(ClickHouseLZ4Stream.java:75)
    at ru.yandex.clickhouse.response.ClickHouseLZ4Stream.read(ClickHouseLZ4Stream.java:61)
    at ru.yandex.clickhouse.response.StreamSplitter.readFromStream(StreamSplitter.java:92)
    at ru.yandex.clickhouse.response.StreamSplitter.next(StreamSplitter.java:63)
    at ru.yandex.clickhouse.response.ClickHouseResultSet.hasNext(ClickHouseResultSet.java:149)
    ... 7 more

Both queries work well when executed one by one. Just in case someone asks why am I doing this, I’ll redirect you to this question.