In very large clusters, the webhdfs client could get bind exceptions because it runs out of ephemeral
ports. This could happen when using webhdfs to talk to the NN in order to do list globbing of a
huge amount of files.
WebHdfsFileSystem#jsonParse gets the input/error stream from the connection,
but never closes the stream. Since it's not closed, the JVM thinks the stream may still
be transferring data, so the next time through this code, it has to get a new connection
rather than reusing an existing one.
The lack of connection reuse has poor latency and adds too much overhead to the NN.