[jira] [Created] (IMPALA-12014) Output a warning message on failed KeepAlive RPC for a Kudu scanner

["Alexey Serbin (Jira)" <ji...@apache.org>]

Alexey Serbin created IMPALA-12014:
--------------------------------------

             Summary: Output a warning message on failed KeepAlive RPC for a Kudu scanner
                 Key: IMPALA-12014
                 URL: https://issues.apache.org/jira/browse/IMPALA-12014
             Project: IMPALA
          Issue Type: Improvement
          Components: Backend, be
    Affects Versions: Impala 4.1.1, Impala 4.2.0, Impala 4.1.0, Impala 3.4.1, Impala 3.4.0, Impala 3.3.0, Impala 4.0.0, Impala 3.2.0, Impala 3.1.0, Impala 2.12.0, Impala 3.0, Impala 2.11.0, Impala 2.10.0, Impala 2.9.0, Impala 2.7.1, Impala 2.8.0, Impala 2.7.0, Impala 4.0.1
            Reporter: Alexey Serbin


With [IMPALA-3292|https://issues.apache.org/jira/browse/IMPALA-3292], the code has been modified to ignore failed KeepAlive RPCs for Kudu scanners because one of the follow-up KeepAlive RPCs usually succeeds within TTL for an idle Kudu scanner.

However, if a Kudu tablet server had been busy for a long time, it might happen that all the consecutive KeepAlive requests failed as well (e.g., if the RPC queue stayed full for the whole interval of the scanner TTL).  If so happened, the corresponding Impala query would fail with an error message in the Impala's query profile like below:

{noformat}
...
    Query Type: QUERY
    Query State: EXCEPTION
    Impala Query State: ERROR
    Query Status: Unable to advance iterator for node with id '1' for Kudu table 'mega_table': Not found: Scanner 4235dd17eb444a36a945f003c23dcf81 not found (it may have expired)
...
{noformat}

However, without a warning message logged by impalad or other clues it's hard to troubleshoot such a situation for people who have not much knowledge of the Kudu specifics.

It would be great to at least log a warning message about failed attempts to send KeepAlive RPC for Kudu scanners.  As of now, the message is logged with {{VLOG(1)}} facility, but verbose logging isn't usually enabled by default for impalad.



--
This message was sent by Atlassian Jira
(v8.20.10#820010)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-all-unsubscribe@impala.apache.org
For additional commands, e-mail: issues-all-help@impala.apache.org