Zookeeper thread leaks in hbase-spark bulkLoad method

In hbase-spark project, HBaseContext provides bulkload methond for loading spark rdd data to hbase easily.But when i using it frequently， the program will throw "cannot create native thread" exception.

using pstack command in spark driver process , the thread num is increasing 

using jstack, named "main-SendThread" and "main-EventThread"  thread so many

It seems like that , connection created before bulkload ,but close method uninvoked at last