Cassandra 无主机可用异常-火花卡桑德拉接头

我在2.3.0版本中使用spark-cassandra-connector_2.11。 运行最新的Spark 2.3.0 正在尝试从Cassandra（3.0.11.1485）DSE（5.0.5）读取数据

示例阅读：无问题工作：

 JavaRDD<Customer> result = javaFunctions(sc).cassandraTable(MyKeyspaceName, "customers", mapRowTo(Customer.class));

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检查您的Cassandra群集是否启用了SSL。在这种情况下，如果您没有配置正确的证书，我会看到相同的错误。

看起来这样解决了它：

.set("spark.cassandra.connection.keep_alive_ms", "1200000")

CassandraConnector cassandraConnector = CassandraConnector.apply(sc.getConf());

SomeSparkRDD.mapPartitions((FlatMapFunction<Iterator<Customer>, CustomerEx>) customerIterator ->
            cassandraConnector.withSessionDo(new AbstractFunction1<Session, Iterator<CustomerEx>>() {
                @Override
                public Iterator<CustomerEx> apply(Session session) {
                    return asStream(customerIterator, false)
                            .map(customer -> fetchDataViaSession(customer, session))
                            .filter(x -> x != null)
                            .iterator();
                }
            }));


public static <T> Stream<T> asStream(Iterator<T> sourceIterator, boolean parallel) {
    Iterable<T> iterable = () -> sourceIterator;
    return StreamSupport.stream(iterable.spliterator(), parallel);
}

spark.cassandra.connection.connections_per_executor_max
spark.cassandra.connection.keep_alive_ms
spark.cassandra.input.fetch.size_in_rows
spark.cassandra.input.split.size_in_mb

Also Tried to reduce the number of Partitions of the RDD which I do mapPartitions+withSessionDo on.

.set("spark.cassandra.connection.keep_alive_ms", "1200000")