Riza Suminto created IMPALA-9612:
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Summary: Runtime filter wait longer than it should be
Key: IMPALA-9612
URL: https://issues.apache.org/jira/browse/IMPALA-9612
Project: IMPALA
Issue Type: Bug
Components: Backend
Reporter: Riza Suminto
Assignee: Riza Suminto
In one of my query profile, I found an info string like this:
Runtime filters: All filters arrived. Waited 59s783ms. Maximum arrival delay:
15s296ms.
If all runtime filters arrived within 15s296ms, then it should not wait until
59s783ms to proceed.
Looking at runtime-filter.cc, It looks like there is a potential race condition
in function RuntimeFilter::WaitForArrival().
bool RuntimeFilter::WaitForArrival(int32_t timeout_ms) const {
unique_lock<mutex> l(arrival_mutex_);
while (arrival_time_.Load() == 0) {
int64_t ms_since_registration = MonotonicMillis() - registration_time_;
int64_t ms_remaining = timeout_ms - ms_since_registration;
if (ms_remaining <= 0) break;
arrival_cv_.WaitFor(l, ms_remaining * MICROS_PER_MILLI);
}
return arrival_time_.Load() != 0;
}
Between checking arrival_time_.Load() and calling arrival_cv_.WaitFor(),
arrival_cv_ might be already signaled by either RuntimeFilter::SetFilter() or
RuntimeFilter::Cancel() because they do not acquire arrival_mutex_ first.
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