火花流驱动程序OOM。 火花流通过HiveExternalCatalog读取hive metastore，然后分析jmap内存使用情况，显示如下：
17 instances of "org.apache.spark.sql.hive.client.IsolatedClientLoader$$anon$1", loaded by "sun.misc.Launcher$AppClassLoader @ 0xe0013a28" occupy 11,312,784 (10.23%) bytes. These instances are referenced from one instance of "java.lang.ThreadLocal$ThreadLocalMap$Entry[]", loaded by "<system class loader>"
我在HiveExternalCatalog / IsolatedClientLoader / HiveClientImpl中找不到关闭函数。如何关闭Hive Metastore客户端连接？