Hi all, The HDFS-347 branch implements short-circuit local reads with support for security. This is just a "heads up" that it is getting ready to merge, and we will probably send out an email about that next week.
HDFS-347 has been under review for a while-- most of the code was written in November and December and reviewed on Apache reviewboard [1]. Recently, we split the JIRA into subtasks and created a branch for them, in order to facilitate review (see the subtasks on HDFS-347.) We have tested HDFS-347 with both random and sequential workloads. The short-circuit case is substantially faster than previously, and overall performance looks very good. This is especially encouraging given that the initial goal of this work was to make security compatible with short-circuit local reads, rather than to optimize the short-circuit code path. For detailed benchmarks, see Todd Lipcon's comment here: [2] best, Colin McCabe [1]. https://reviews.apache.org/r/8554/ [2]. https://issues.apache.org/jira/browse/HDFS-347?focusedCommentId=13551755&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13551755
