impala git commit: IMPALA-6423: HDFS scanner doesn't check RuntimeState::is_cancelled()

[ta...@apache.org]

Repository: impala
Updated Branches:
  refs/heads/master 3a049a530 -> 8302608bd


IMPALA-6423: HDFS scanner doesn't check RuntimeState::is_cancelled()

There are cancellation checks in HDFS scanner code that are using
ScannerContext::cancelled(), however, if an internal cancellation
happens then RuntimeState::is_cancelled() should also be checked to
detect these. As a solution I extended ScannerContext::cancelled() to
check RuntimeState::is_cancelled() as well.

Creating automatic tests for this is difficult as the result of the
query is actually the same with and without this change. With manual
tests I verifyed that in case an internal cancel happens (I made the
exchange node fail during a select query) this change prevents
CommitRows() being executed multiple times even if the query had been
cancelled before the first call.

Change-Id: I3eb960d9d6f2dde4b2cb4988aa06288d11802b9a
Reviewed-on: http://gerrit.cloudera.org:8080/9352
Reviewed-by: Tim Armstrong <ta...@cloudera.com>
Tested-by: Impala Public Jenkins


Project: http://git-wip-us.apache.org/repos/asf/impala/repo
Commit: http://git-wip-us.apache.org/repos/asf/impala/commit/8302608b
Tree: http://git-wip-us.apache.org/repos/asf/impala/tree/8302608b
Diff: http://git-wip-us.apache.org/repos/asf/impala/diff/8302608b

Branch: refs/heads/master
Commit: 8302608bdff15d6e8af324fc885dd0a8c2b44a5d
Parents: 3a049a5
Author: Gabor Kaszab <ga...@cloudera.com>
Authored: Wed Feb 14 12:39:03 2018 +0100
Committer: Impala Public Jenkins <im...@gerrit.cloudera.org>
Committed: Tue Feb 20 00:45:48 2018 +0000

----------------------------------------------------------------------
 be/src/exec/scanner-context.cc | 1 +
 be/src/exec/scanner-context.h  | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/impala/blob/8302608b/be/src/exec/scanner-context.cc
----------------------------------------------------------------------
diff --git a/be/src/exec/scanner-context.cc b/be/src/exec/scanner-context.cc
index 0311f0e..abdde07 100644
--- a/be/src/exec/scanner-context.cc
+++ b/be/src/exec/scanner-context.cc
@@ -330,6 +330,7 @@ void ScannerContext::Stream::ReturnIoBuffer() {
 }
 
 bool ScannerContext::cancelled() const {
+  if (state_->is_cancelled()) return true;
   if (!scan_node_->HasRowBatchQueue()) return false;
   return static_cast<HdfsScanNode*>(scan_node_)->done();
 }

http://git-wip-us.apache.org/repos/asf/impala/blob/8302608b/be/src/exec/scanner-context.h
----------------------------------------------------------------------
diff --git a/be/src/exec/scanner-context.h b/be/src/exec/scanner-context.h
index 09a4bdc..a131d3f 100644
--- a/be/src/exec/scanner-context.h
+++ b/be/src/exec/scanner-context.h
@@ -359,8 +359,9 @@ class ScannerContext {
   /// context.
   Stream* AddStream(io::ScanRange* range);
 
-  /// Returns false if scan_node_ is multi-threaded and has been cancelled.
-  /// Always returns false if the scan_node_ is not multi-threaded.
+  /// Returns true if RuntimeState::is_cancelled() is true, or if scan node is not
+  /// multi-threaded and is done (finished, cancelled or reached it's limit).
+  /// In all other cases returns false.
   bool cancelled() const;
 
   HdfsPartitionDescriptor* partition_descriptor() { return partition_desc_; }