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From "Stefan Podkowinski (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-13234) Add histogram for delay to deliver hints
Date Tue, 21 Feb 2017 15:36:44 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-13234?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15876160#comment-15876160
] 

Stefan Podkowinski commented on CASSANDRA-13234:
------------------------------------------------

This would be interesting to have.

Some points I've noticed with the patch so far:

HintedHandoffMetrics
* Exception handling in {{updateDelayMetrics}} should only be required in case CacheLoader
is known to throw exceptions. I don't think that's being the case here and {{getUnchecked}}
can be used just as in the incrCreatedHints methods. Otherwise, if there are potential exceptions
we need to catch, this would have to happen for incrCreatedHints as well, as the cache loader
implementation is nearly identical.
* {{if(delay <= 0)}} early exit condition should output warning log message, as this would
be very unusual behaviour.
* Unused {{import java.util.Map;}} statement
* Can you change the {{Hint_delays-global}} notation to simply {{Hint_delay}}, so that the
individual IP based metrics can be filtered using a {{Hint_delays-*}} pattern? 

HintsDispatcher
* {{ApproximateTime.currentTimeMillis()}} should be prefered for this use-case instead of
System (not available in 3.0)

Hint + EncodedHintMessage
* Throws declaration of {{IllegalArgumentException}} looks strange to me, especially on a
method without arguments. Why declare the runtime exception at all?
* Unused {{import java.util.*;}} statement in trunk

Other
* New metrics missing in [documentation|http://cassandra.apache.org/doc/latest/operating/metrics.html#hintedhandoff-metrics]



> Add histogram for delay to deliver hints
> ----------------------------------------
>
>                 Key: CASSANDRA-13234
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13234
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Observability
>            Reporter: Jeff Jirsa
>            Assignee: Jeff Jirsa
>            Priority: Minor
>             Fix For: 3.0.x, 3.11.x
>
>
> There is very little visibility into hint delivery in general - having histograms available
to understand how long it takes to deliver hints is useful for operators to better identify
problems. 



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