[jira] [Created] (IMPALA-7598) Planner timeline not set in the runtime profile incase of errors

["bharath v (JIRA)" <ji...@apache.org>]

bharath v created IMPALA-7598:
---------------------------------

             Summary: Planner timeline not set in the runtime profile incase of errors
                 Key: IMPALA-7598
                 URL: https://issues.apache.org/jira/browse/IMPALA-7598
             Project: IMPALA
          Issue Type: Bug
          Components: Frontend
    Affects Versions: Impala 3.1.0
            Reporter: bharath v


Currently, the frontend sets the "Query compilation" timeline only if doCreateExecRequest() finishes successfully.
{code}
private TExecRequest doCreateExecRequest(TQueryCtx queryCtx...) {
  ...... <snip>......
  timeline.markEvent("Planning finished");
  result.setTimeline(timeline.toThrift());
  return result;
}
{code}

There can be cases where the timeline could be useful for debugging when the planning fails. 

One recent case I came across is the exhaustion of retries on InconsistentMetadataFetchException. For every retry of query due to this exception, we add a timeline event.

{code}
 while (true) {
      try {
        return doCreateExecRequest(queryCtx, timeline, explainString);
      } catch (InconsistentMetadataFetchException e) {
        if (attempt++ == INCONSISTENT_METADATA_NUM_RETRIES) {
          throw e;
        }
        if (attempt > 1) {
          // Back-off a bit on later retries.
          Uninterruptibles.sleepUninterruptibly(200 * attempt, TimeUnit.MILLISECONDS);
        }
        timeline.markEvent(
            String.format("Retrying query planning due to inconsistent metadata "
                    + "fetch, attempt %s of %s: ",
                attempt, INCONSISTENT_METADATA_NUM_RETRIES)
            + e.getMessage());
{code}

However, if the planning eventually fails, the timeline about retries is gone. This would've confirmed that the query was re-tried for 10 times.

Would be really useful if we can populate the partial timeline, even if the planning failed.





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