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https://issues.apache.org/jira/browse/IMPALA-539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16692475#comment-16692475
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Michael Ho commented on IMPALA-539:
-----------------------------------
Ideally, we should always wait for all backend completion even in the case of
cancellation below. Of course, this may be problematic if a backend is
unresponsive for whatever reason so we can wait with a timeout once the
cancellation RPCs have been issued.
{noformat}
void Coordinator::HandleExecStateTransition(
const ExecState old_state, const ExecState new_state) {
static const unordered_map<ExecState, const char *> exec_state_to_event{
{ExecState::EXECUTING, "Executing"},
{ExecState::RETURNED_RESULTS, "Last row fetched"},
{ExecState::CANCELLED, "Execution cancelled"},
{ExecState::ERROR, "Execution error"}};
if (old_state == new_state) return;
// Once we enter a terminal state, we stay there, guaranteeing this code runs
only once.
DCHECK_EQ(old_state, ExecState::EXECUTING);
// Should never transition to the initial state.
DCHECK_NE(new_state, ExecState::EXECUTING);
// Can't transition until the exec RPCs are no longer in progress. Otherwise,
a
// cancel RPC could be missed, and resources freed before a backend has had a
chance
// to take a resource reference.
DCHECK(exec_rpcs_complete_barrier_ != nullptr &&
exec_rpcs_complete_barrier_->pending() <= 0) << "exec rpcs not completed";
query_events_->MarkEvent(exec_state_to_event.at(new_state));
// This thread won the race to transitioning into a terminal state - terminate
// execution and release resources.
ReleaseExecResources();
if (new_state == ExecState::RETURNED_RESULTS) {
// TODO: IMPALA-6984: cancel all backends in this case too.
WaitForBackends(); <<-----
} else {
CancelBackends(); <<----- should wait for backend completion too in this
case.
}
ReleaseAdmissionControlResources();
// Can compute summary only after we stop accepting reports from the
backends. Both
// WaitForBackends() and CancelBackends() ensures that.
// TODO: should move this off of the query execution path?
ComputeQuerySummary();
{noformat}
> Impala should gather final runtime profile from fragments for
> aborted/cancelled query
> -------------------------------------------------------------------------------------
>
> Key: IMPALA-539
> URL: https://issues.apache.org/jira/browse/IMPALA-539
> Project: IMPALA
> Issue Type: Improvement
> Components: Backend
> Affects Versions: Impala 1.1
> Reporter: Alan Choi
> Priority: Minor
> Labels: query-lifecycle
>
> For cancelled/aborted queries, the final runtime profile from plan fragments
> are not recorded and reported by the coordinator. For short running queries,
> we won't see any profile at all because no intermediate runtime profile has
> been sent.
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