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https://issues.apache.org/jira/browse/UIMA-6136?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16957937#comment-16957937
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Richard Eckart de Castilho commented on UIMA-6136:
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I wonder if the sharing of comparators is actually beneficial. If there is a
small number of CASes, the memory-savings are small. If there is a large number
of CASes, the performance impact is quite noticeable - in particular if the
CASes are not re-used. So significant savings probably only happen if there is
a large number of CASes with the same or similar type systems that are actually
being re-used. Maybe this optimization could be made optional, either via a
global flag or maybe even by checking if the CAS lives in a CAS Pool (if it
does, it is likely to be re-used, otherwise probably not).
> FSIndexComparatorImpl.equalsWithoutType() gets slow for many CASes with the
> same TS
> -----------------------------------------------------------------------------------
>
> Key: UIMA-6136
> URL: https://issues.apache.org/jira/browse/UIMA-6136
> Project: UIMA
> Issue Type: Bug
> Components: UIMA
> Affects Versions: 3.1.0SDK
> Reporter: Richard Eckart de Castilho
> Priority: Minor
> Attachments: 2019-10-21_22-23-37.png, 2019-10-21_22-44-25.png
>
>
> When creating several hundred CASes with the same type system, the
> `shareExisting` mechanism which is designed to save on memory starts eating
> into CPU time quite a lot.
> This screenshot shows that in my particular case, the method is called ~11mio
> times and takes the bulk of the processing time. The call hierarchy is a bit
> messed up though - actually this happens when the CASes are initialized.
> !2019-10-21_22-44-25.png|width=100%!
> The second screenshot shows the actual call hierarchy, but for some reason,
> the profile doesn't properly dive into the `equals` method here and doesn't
> count the time spent in `equalsWithoutType`.
> !2019-10-21_22-23-37.png|width=100%!!
> So either the method shouldn't be called that often - or - it should be way
> faster.
> In the example, I have like 1800 CAS instances and their type system has
> upwards of 200 types.
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