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From "Scooletz (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-6998) HintedHandoff - expired hints may block future hints deliveries
Date Tue, 08 Apr 2014 14:06:19 GMT


Scooletz commented on CASSANDRA-6998:

Thx [~iamaleksey] for your quick comment, I think this problem is not solved yet though. In
the comments section of the issue referenced by you
[~gsanderson] asks:
One quick question... this patch will hopefully prevent us getting into this state in many
cases, unless you have a huge number of hints for a node that is down for a very long time:
since there is no auto-compaction, a large number of hints may have expired from TTL, thus
preventing any further hint delivery.

That's the case I'm referring to. I got this Is it covered by 6666? If not, is it considered
as a bug? I added stacktrace to the issue.

> HintedHandoff - expired hints may block future hints deliveries
> ---------------------------------------------------------------
>                 Key: CASSANDRA-6998
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: - cluster of two DCs: DC1, DC2
> - keyspace using NetworkTopologyStrategy (replication factors for both DCs)
> - heavy load (write:read, 100:1) with LOCAL_QUORUM using Java driver setup with DC awareness,
writing to DC1
>            Reporter: Scooletz
>              Labels: HintedHandoff, TTL
>             Fix For: 2.0.3
> For tests purposes, DC2 was shut down for 1 day. The _hints_ table was filled with millions
of rows. Now, when _HintedHandOffManager_ tries to _doDeliverHintsToEndpoint_  it queries
the store with QueryFilter.getSliceFilter which counts deleted (TTLed) cells and throws org.apache.cassandra.db.filter.TombstoneOverwhelmingException.

> Throwing this exception stops the manager from running compaction as it is run only after
successful handoff. This leaves the HH practically disabled till administrator runs truncateAllHints.

> Wouldn't it be nicer if on org.apache.cassandra.db.filter.TombstoneOverwhelmingException
run compaction? That would remove TTLed hints leaving whole HH mechanism in a healthy state.

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