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IMPALA-10050: Fixed DCHECK error for backend in terminal state.

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Recent patch for IMPALA-6788 makes coordinator to cancel inflight
query fragment instances when it receives failure report from one
backend. It's possible the BackendState::Cancel() is called for
one fragment instance before the first execution status report
from its backend is received and processed by the coordinator.
Since the status of BackendState is set as Cancelled after Cancel()
is called, the execution of the fragment instance is treated as
Done in such case so that the status report will NOT be processed.
Hence the backend receives response OK from coordinator even it
sent a report with execution error. This make backend hit DCHECK
error if backend in the terminal state with error.
This patch fixs the issue by making coordinator send CANCELLED
status in the response of status report if the backend status is not
ok and the execution status report is not applied.

Testing:
 - The issue could be reproduced by running test_failpoints for about
   20 iterations. Verified the fixing by running test_failpoints over
   200 iterations without DCHECK failure.
 - Passed TestProcessFailures::test_kill_coordinator.
 - Psssed TestRPCException::test_state_report_error.
 - Passed exhaustive tests.

Change-Id: Iba6a72f98c0f9299c22c58830ec5a643335b966a
Reviewed-on: http://gerrit.cloudera.org:8080/16303
Reviewed-by: Thomas Tauber-Marshall <tmarshall@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
This commit is contained in:
wzhou-code
2020-08-06 15:52:47 -07:00
committed by Impala Public Jenkins
parent 34668fab87
commit 3733c4cc2c
3 changed files with 20 additions and 10 deletions
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7
be/src/runtime/coordinator.cc
View File

@@ -1005,7 +1005,12 @@ Status Coordinator::UpdateBackendExecStatus(const ReportExecStatusRequestPB& req
// If query execution has terminated, return a cancelled status to force the fragment
// instance to stop executing.
return IsExecuting() ? Status::OK() : Status::CANCELLED;
// After cancelling backend_state, it's possible that current exec_state is still
// EXECUTING but the backend status is not OK since execution status report is not
// applied to update the overall status. In such case, we should return a cancelled
// status to backend.
return (IsExecuting() && backend_state->GetStatus().ok()) ? Status::OK() :
Status::CANCELLED;
}
Status Coordinator::UpdateBlacklistWithAuxErrorInfo(

20
be/src/runtime/query-exec-mgr.cc
View File

@@ -226,15 +226,17 @@ void QueryExecMgr::CancelQueriesForFailedCoordinators(
// Build a list of queries that are scheduled by failed coordinators (as
// evidenced by their absence from the cluster membership list).
std::vector<QueryCancellationTask> to_cancel;
qs_map_.DoFuncForAllEntries([&](QueryState* qs) {
if (qs != nullptr && !qs->IsCancelled()) {
if (current_membership.find(qs->coord_backend_id()) == current_membership.end()) {
// decremented by ReleaseQueryState()
AcquireQueryStateLocked(qs);
to_cancel.push_back(QueryCancellationTask(qs));
}
}
});
ExecEnv::GetInstance()->query_exec_mgr()->qs_map_.DoFuncForAllEntries(
[&](QueryState* qs) {
if (qs != nullptr && !qs->IsCancelled()) {
if (current_membership.find(qs->coord_backend_id())
== current_membership.end()) {
// decremented by ReleaseQueryState()
AcquireQueryStateLocked(qs);
to_cancel.push_back(QueryCancellationTask(qs));
}
}
});
// Since we are the only producer for the cancellation thread pool, we can find the
// remaining capacity of the pool and submit the new cancellation requests without

3
be/src/runtime/query-state.cc
View File

@@ -806,6 +806,9 @@ done:
DCHECK(entry.second->IsDone());
}
} else {
// If the query execution hit an error, when the final status report is sent, the
// coordinator's response will instruct the QueryState to cancel itself, so Cancel()
// should have always been called by this point.
DCHECK_EQ(is_cancelled_.Load(), 1);
}
}