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https://issues.apache.org/jira/browse/KNOX-1093?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16234243#comment-16234243
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Sandeep More commented on KNOX-1093:
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[~rajeshc] I think this is a good catch, if you want an immediate solution you
can change the retry count to, say 1, and the failover will kick in.
Now for a long term solution, the retryRequest() code definitely needs to be
reworked, given it is almost identical to failoverRequest. Infact we could
change it to failoverRequest() and that should push the SafeMode node at the
bottom of the HA list.
> KNOX Not Handling safemode state of one of the NameNode In HA state
> --------------------------------------------------------------------
>
> Key: KNOX-1093
> URL: https://issues.apache.org/jira/browse/KNOX-1093
> Project: Apache Knox
> Issue Type: Bug
> Components: Server
> Affects Versions: 0.10.0
> Reporter: Rajesh Chandramohan
> Priority: Major
> Fix For: 0.15.0
>
>
> per your code WebHdfsHaDispatch.java , When Safemode exception happened it
> calls the retryRequest() method. which also calls executeRequest() method as
> like failover request but the namenode info is not changing for the thread
> for all of its iteration until maxRetryAttempts=300
> and retrySleep=1000 ( 1 sec )
> After Max 5 minutes , client retries should pick the right namenode atleast
> in next attempt.
> But in this case if we need to copy a set of files in stipulated time there
> is X% of connections falls into these namenode and fails. Can we handle that
> better
> {code:java}
> try {
> inboundResponse = executeOutboundRequest(outboundRequest);
> writeOutboundResponse(outboundRequest, inboundRequest,
> outboundResponse, inboundResponse);
> } catch (StandbyException e) {
> LOG.errorReceivedFromStandbyNode(e);
> failoverRequest(outboundRequest, inboundRequest, outboundResponse,
> inboundResponse, e);
> } catch (SafeModeException e) {
> LOG.errorReceivedFromSafeModeNode(e);
> retryRequest(outboundRequest, inboundRequest, outboundResponse,
> inboundResponse, e);
> } catch (IOException e) {
> LOG.errorConnectingToServer(outboundRequest.getURI().toString(), e);
> failoverRequest(outboundRequest, inboundRequest, outboundResponse,
> inboundResponse, e);
> }
> }
> {code}
> Need to change the logic in SafeModeexception state in KNOX HADispatch code
> to flag the namenode which is stuck in safemode and maintain don't try queue
> and redirect all further connection only to healthy active namenode . This
> way X5 of failures we can handle. What do we think
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