HDFS commandline calls can be expensive due to JVM
startup and other costs. Since most HDFS commandline
calls can take multiple paths, one way to reduce
execution time is to consolidate multiple HDFS
commands into a single HDFS call. Since HDFS put
commands will follow symbolic links and can copy
recursively, this can allow for further consolidation
by creating the full directory structure and
copying it in a single HDFS call.
This does several of these optimizations throughout
the dataload codepath. It saves a few seconds here
and there:
Loading Hive Builtins: 1:10 -> 0:30
Loading custom schemas: 0:35 -> 0:20
Loading Hive UDFs: 0:45 -> 0:25
Change-Id: I0934353329dc7312394fc4457ab8db2a272c6282
Reviewed-on: http://gerrit.cloudera.org:8080/10120
Reviewed-by: Philip Zeyliger <philip@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
da363a99a4