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From "Paulo Motta (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-12905) Retry acquire MV lock on failure instead of throwing WTE on streaming
Date Wed, 14 Dec 2016 20:27:58 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-12905?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15749378#comment-15749378
] 

Paulo Motta commented on CASSANDRA-12905:
-----------------------------------------

bq. But by making hint delivery async, you made it droppable again. I guess this is not intentional?


Sorry, should have made it a bit clearer since this was a change from the original idea. Basically,
the hint sender will consider the request failed after {{write_request_timeout_in_ms}} and
retry, so it does not make sense for the receiver to retry applying hints for longer than
that since this can cause the node to become overloaded.

I believe that making hints deferrable will free up some resources and reduce contetion, what
should reduce the number of WTEs. Furthermore things like CASSANDRA-10981 should also help
in this case. The issue with MV hints timing out can be further improved by reducing the {{hinted_handoff_throttle_in_kb}}.
If this is not sufficient, we can make a new ticket to try to improve this or use a lower
throttle for MV tables.

bq. You also do not reply on an exception. I am not familiar with request/response handling
but I guess an exception (like WTE) will just drop the hint and let the hint-sender wait for
a reply infinitely or until it times out?

I just kept the old behavior of responding only in case of success, in this case if there
is a failure the sender will retry after timeout anyway.

Test result look good so far.  I added a regression dtest to make sure we test against this
in the future ([pull request|https://github.com/riptano/cassandra-dtest/pull/1408]), and submitted
a final CI round. If everything looks good I will squash and commit.

Thanks!

> Retry acquire MV lock on failure instead of throwing WTE on streaming
> ---------------------------------------------------------------------
>
>                 Key: CASSANDRA-12905
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12905
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Streaming and Messaging
>         Environment: centos 6.7 x86_64
>            Reporter: Nir Zilka
>            Assignee: Benjamin Roth
>            Priority: Critical
>             Fix For: 3.10
>
>
> Hello,
> I performed two upgrades to the current cluster (currently 15 nodes, 1 DC, private VLAN),
> first it was 2.2.5.1 and repair worked flawlessly,
> second upgrade was to 3.0.9 (with upgradesstables) and also repair worked well,
> then i upgraded 2 weeks ago to 3.9 - and the repair problems started.
> there are several errors types from the system.log (different nodes) :
> - Sync failed between /xxx.xxx.xxx.xxx and /xxx.xxx.xxx.xxx
> - Streaming error occurred on session with peer xxx.xxx.xxx.xxx Operation timed out -
received only 0 responses
> - Remote peer xxx.xxx.xxx.xxx failed stream session
> - Session completed with the following error
> org.apache.cassandra.streaming.StreamException: Stream failed
> ----
> i use 3.9 default configuration with the cluster settings adjustments (3 seeds, GossipingPropertyFileSnitch).
> streaming_socket_timeout_in_ms is the default (86400000).
> i'm afraid from consistency problems while i'm not performing repair.
> Any ideas?
> Thanks,
> Nir.



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