[jira] [Commented] (LUCENE-5638) Default Attributes are expensive

["Uwe Schindler (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-5638?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13987965#comment-13987965 ] 

Uwe Schindler commented on LUCENE-5638:
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bq. Changes like LUCENE-5634 make it clear that the default AttributeFactory stuff has a very high cost: weakmaps/reflection/etc.

The problem are not the weak maps and reflections. The reason why it is expensive is the fact that all attribute instances have to be put into the 2 LinkedHashMaps on creating the TokenStream. I just repeat: It is not the refection! We had this discussion already back 5 years ago with Michael Busch!

In addition, the AttributeFactory itsself has less impact (this was already tested while developing it in 2.9). This is why the weak maps are there - so it is fast, the *only* reflection ever happens is: Class#newInstance() is cheap in recent Java versions, the speed difference in micro benchmarks is small, as fast as a native {{new}}.

So I disagree with removing the default AttributeFactory, we still need it for non-default attributes, so: The simple workaround would be to use TOKEN_ATTRIBUTE_FACTORY instead, which falls back to the default one for unknown attributes.

I agree with clearAttributes(), but this should be solved with TOKEN_ATTRIBUTE_FACTORY , too.

> Default Attributes are expensive
> --------------------------------
>
>                 Key: LUCENE-5638
>                 URL: https://issues.apache.org/jira/browse/LUCENE-5638
>             Project: Lucene - Core
>          Issue Type: Bug
>          Components: modules/analysis
>            Reporter: Robert Muir
>
> Changes like LUCENE-5634 make it clear that the default AttributeFactory stuff has a very high cost: weakmaps/reflection/etc.
> Additionally I think clearAttributes() is more expensive than it should be: it has to traverse a linked-list, calling clear() per token.
> Operations like cloning (save/restoreState) have a high cost tll.
> Maybe we can have a better Default? In other words, rename DEFAULT_ATTRIBUTE_FACTORY to REFLECTION_ATTRIBUTE_FACTORY, and instead have a faster default factory that just has one AttributeImpl with the "core ones" that 95% of users are dealing with (TOKEN_ATTRIBUTE_FACTORY?): anything outside of that falls back to reflection.



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