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https://issues.apache.org/jira/browse/SOLR-14657?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris M. Hostetter updated SOLR-14657:
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Attachment: SOLR-14657.patch
Status: Open (was: Open)
attaching a patch that adds a small private helper method to SolrIndexSearcher
that wraps the IndexReader realted gauges in a trivial gague that silently
ignores AlreadyClosedException and returns null when this happens.
[~ab] - interested in your thoughts on this, in particular wether you can think
of any problems with a gauge returning 'null' – while the {{Gague}} javadocs
are a little vague, 'null" seems like the "sane" thing for a gauge to return
when the value is "currently unknowable" and i _assume_ is something that
monitoring systems should expect as a possible indicator of "unknown" values
... but i notice you chose "-1" in a similar exception handling situation for
the "indexCommitSize" Gauge, so i'm not sure.
(In general returning -1, or 0, Integer.MIN_VALUE, or any other non-null value
when the "real" value is unknown seems like it would lead to misleading rolling
averages, confusing graphs, etc...)
> spurious ERRORs due to race condition between SolrIndexSearcher metrics and
> IndexReader closing
> -----------------------------------------------------------------------------------------------
>
> Key: SOLR-14657
> URL: https://issues.apache.org/jira/browse/SOLR-14657
> Project: Solr
> Issue Type: Improvement
> Security Level: Public(Default Security Level. Issues are Public)
> Reporter: Chris M. Hostetter
> Assignee: Chris M. Hostetter
> Priority: Major
> Attachments: SOLR-14657.patch
>
>
> I've seen situations in the wild where systems monitoring/polling metrics can
> trigger scary looking - but otherwise benign - ERRORs due to
> AlreadyClosedExceptions if/when the searcher/reader is in the process of
> being re-opened and the Gauge tries to call reader.numDocs(), etc...
> We should tweak the metrics logic to just ignore these exceptions
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