Github user kayousterhout commented on the pull request:
https://github.com/apache/spark/pull/900#issuecomment-45786350
@li-zhihui it looks like the JIRA you created
(https://issues.apache.org/jira/browse/SPARK-1946) describes the issue fixed by
#892 and described by a redundant issue
(https://issues.apache.org/jira/browse/SPARK-1937). As @mridulm explained
(thanks!!), the primary set of issues addressed by this pull request center
around the fact that Spark-on-YARN has various performance problems when not
enough executors have registered yet. Could you update SPARK-1946 accordingly?
@tgravescs I'm a little nervous about adding more scheduler config options,
because I think the average user would have a very difficult time figuring out
that their performance problems could be fixed by tuning this particular set of
options. The scheduler already has quite a few config options and I think we
should be very cautious in adding more (cc @pwendell). On the other hand, as
you pointed out, it seems like a user typically wants to wait for some number
of executors to become available, and those semantics aren't available to the
application -- so we're stuck with adding something to the scheduler code. Is
it possible to do this only for the YARN scheduler / do you think it's
necessary in standalone too? Doing it only for YARN (and naming the config
variable accordingly) could help signal to a naive user when tuning this might
help. From @mridulm's description, it sounds like many of the issues here are
yarn-specific.
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