Pau Garcia Rodriguez created ARROW-18431:
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Summary: Acero's Execution Plan never finishes.
Key: ARROW-18431
URL: https://issues.apache.org/jira/browse/ARROW-18431
Project: Apache Arrow
Issue Type: Bug
Components: C++
Affects Versions: 10.0.0
Reporter: Pau Garcia Rodriguez
We have observed that sometimes an execution plan with a small input never
finishes (the future returned by the ExecPlan::finished() method is never
marked as finished), even though the generator in the sink node is exhausted
and has returned nullopt.
This issue seems to happen at random, the same plan with the same input
sometimes works (the plan is marked finished) and sometimes it doesn't. Since
the ExecPlanImpl destructor forces the executing thread to wait for the plan to
finish (when the plan has not yet finished) we enter in a deadlock waiting for
a plan that never finishes.
Since this has only happened with small inputs and not in a deterministic way,
we believe the issue might be in the ExecPlan::StartProducing method.
Our hypothesis is that after the plan starts producing on each node, each node
schedules their tasks and they are immediately finished (due to the small
input) and somehow the callback that marks the future finished_ finished is
never executed.
{code:java}
Status StartProducing() {
...
Future<> scheduler_finished =
util::AsyncTaskScheduler::Make([this(util::AsyncTaskScheduler* async_scheduler)
{
...
scheduler_finished.AddCallback([this](const Status& st) {
finished_.MarkFinished(st);});
...
}{code}
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