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https://issues.apache.org/jira/browse/IMPALA-15115?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Smith resolved IMPALA-15115.
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Fix Version/s: Impala 5.0.0
Resolution: Fixed
> Race condition where GetOperationStatus() may return error when query is
> retried
> --------------------------------------------------------------------------------
>
> Key: IMPALA-15115
> URL: https://issues.apache.org/jira/browse/IMPALA-15115
> Project: IMPALA
> Issue Type: Bug
> Components: Backend
> Affects Versions: Impala 5.0.0
> Reporter: Joe McDonnell
> Assignee: Joe McDonnell
> Priority: Critical
> Fix For: Impala 5.0.0
>
>
> In HS2's GetOperationStatus() and Beeswax's get_state(), the code looks like
> this:
> {code:java}
> void ImpalaServer::GetOperationStatus(TGetOperationStatusResp& return_val,
> const TGetOperationStatusReq& request) {
> ...
> status = GetActiveQueryHandle(query_id, &query_handle); <---- #1
> ...
> // When using long polling, this waits up to long_polling_time_ms
> milliseconds for
> // query completion.polling
> query_handle->WaitForCompletionExecState(); <---- #2
> ...
> {
> lock_guard<mutex> l(*query_handle->lock());
> TOperationState::type operation_state = query_handle->TOperationState();
> return_val.__set_operationState(operation_state); <---- #3
> if (operation_state == TOperationState::ERROR_STATE) {
> DCHECK(!query_handle->query_status().ok());
> return_val.__set_errorMessage(Substitute(QUERY_ERROR_FORMAT,
> PrintId(query_id), query_handle->query_status().GetDetail()));
> return_val.__set_sqlState(SQLSTATE_GENERAL_ERROR);
> } else {
> ClientRequestState::RetryState retry_state =
> query_handle->retry_state();
> if (retry_state != ClientRequestState::RetryState::RETRYING
> && retry_state != ClientRequestState::RetryState::RETRIED) {
> DCHECK(query_handle->query_status().ok());
> }
> }{code}
> If we get the active query handle in #1, then it fails and gets retried
> before #3, GetOperationStatus() will return an error even though the query is
> being retried. This is deterministic with long polling, because it waits for
> significant time at #2 and gets posted out when the query hits an error.
> However, this can happen without long polling, and it might be causing some
> flakiness for some of our retry tests.
> When we have the lock, if the query hit an error, we should check to see if
> it was retried. If it was retried, we can call GetActiveQueryHandle() to get
> the new handle and then return its status.
> The same basic issue exists for Beeswax as well. This is a blocker for
> enabling long polling by default.
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