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https://issues.apache.org/jira/browse/HBASE-20603?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16489597#comment-16489597
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Andrew Purtell edited comment on HBASE-20603 at 5/24/18 7:15 PM:
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bq. Do you think creating a new FastLongHistogram on every metrics snapshot
(and all of the stuff inside of it) a concern
There is no other way to do it without modifying FLH itself. Sure, I could hack
that, but then it changes everything, even legacy users of FLH. If you think
that is fine, then I could do whatever I like with FLH. Some unit tests for FLH
that expect new bins to inherit state from old bins will have to be removed.
Note internally at every snapshot in FLH a new Bins object is allocated, which
is the bulk of allocation for FLH state.
It's true that this change does in effect a double allocation of Bins for every
reset. That is a concession to legacy as mentioned above. I'm not sure how much
of a concern it will be in practice. I doubt the extra object will ever leave
eden or TLAB, and won't have a measurable impact unless we construct an
artificial test case that resets a million histograms at once or something like
that.
was (Author: apurtell):
> Do you think creating a new FastLongHistogram on every metrics snapshot (and
> all of the stuff inside of it) a concern
There is no other way to do it without modifying FLH itself. Sure, I could hack
that, but then it changes everything, even legacy users of FLH. If you think
that is fine, then I could do whatever I like with FLH. Some unit tests for FLH
that expect new bins to inherit state from old bins will have to be removed.
Note internally at every snapshot in FLH a new Bins object is allocated, which
is the bulk of allocation for FLH state.
It's true that this change does in effect a double allocation of Bins for every
reset. That is a concession to legacy as mentioned above. I'm not sure how much
of a concern it will be in practice. I doubt the extra object will ever leave
eden or TLAB, and won't have a measurable impact unless we construct an
artificial test case that resets a million histograms at once or something like
that.
> Histogram metrics should reset min and max
> ------------------------------------------
>
> Key: HBASE-20603
> URL: https://issues.apache.org/jira/browse/HBASE-20603
> Project: HBase
> Issue Type: Bug
> Components: metrics
> Reporter: Andrew Purtell
> Assignee: Andrew Purtell
> Priority: Minor
> Attachments: HBASE-20603-branch-1-WIP.patch
>
>
> It's weird that the bins are reset at every monitoring interval but min and
> max are tracked over the lifetime of the process. Makes it impossible to set
> alarms on max value as they'll never shut off unless the process is
> restarted. Histogram metrics should reset min and max at snapshot time too.
> For discussion.
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