Todd Lipcon has submitted this change and it was merged.

Change subject: spark: continue scanning after encountering empty batch
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spark: continue scanning after encountering empty batch

The Spark connector would previously stop scanning after the first empty
batch returned by a tablet server. The tablet server will not return an
empty batch when there are rows remaining in the tablet unless the scan
hits an internal timeout of 500ms[1]. This can only realistically happen
on large scans with highly selective predicates on data not in the block
cache. As a result this behavior only occurs with very large tables on
slow tablet server, which makes it very hard to test.  No unit tests are
included with this patch, but the fix has been verified on a real
cluster exhibiting the issue.

[1] 
https://github.com/apache/kudu/blob/2ed179a7a188b4748a43a829940764ab5dddbc1c/src/kudu/tserver/tablet_service.cc#L1670

Change-Id: I4fdb7836a27940cab674100da0ef0ea5e050bbdd
Reviewed-on: http://gerrit.cloudera.org:8080/5531
Tested-by: Kudu Jenkins
Reviewed-by: Chris George <[email protected]>
Reviewed-by: Todd Lipcon <[email protected]>
---
M java/kudu-spark/src/main/scala/org/apache/kudu/spark/kudu/KuduRDD.scala
1 file changed, 2 insertions(+), 2 deletions(-)

Approvals:
  Chris George: Looks good to me, but someone else must approve
  Todd Lipcon: Looks good to me, approved
  Kudu Jenkins: Verified



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Gerrit-MessageType: merged
Gerrit-Change-Id: I4fdb7836a27940cab674100da0ef0ea5e050bbdd
Gerrit-PatchSet: 2
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Dan Burkert <[email protected]>
Gerrit-Reviewer: Chris George <[email protected]>
Gerrit-Reviewer: Jean-Daniel Cryans <[email protected]>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Todd Lipcon <[email protected]>

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