[jira] [Commented] (COMPRESS-285) checking of availability of XZ compression is expensive - result should be reused

["Stefan Bodewig (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/COMPRESS-285?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14052155#comment-14052155 ] 

Stefan Bodewig commented on COMPRESS-285:
-----------------------------------------

I understand the problem but am not sure we can fix it without breaking support for OSGi.  The dependency on XZ is labeled optional in the OSGi part of the manifest and in theory it may be made available or removed at any point of time.

> checking of availability of XZ compression is expensive - result should be reused
> ---------------------------------------------------------------------------------
>
>                 Key: COMPRESS-285
>                 URL: https://issues.apache.org/jira/browse/COMPRESS-285
>             Project: Commons Compress
>          Issue Type: Improvement
>          Components: Compressors
>    Affects Versions: 1.5, 1.6, 1.7, 1.8
>         Environment: linux 64-bit, java 7, glassfish, solr, tika
>            Reporter: Wojciech Łozowicki
>            Priority: Minor
>              Labels: performance
>
> I use solr with apache tika for indexing documents. Tika uses commons-compress to handle compressed files. Using sampler (jvisualvm) I have seen that quite a lot of time (5-7%) during my tests is spent in XZUtils.isXZCompressionAvailable because of unavailable XZ compression (I guess for each time classloaders spend some time looking for unavailable classes, then NoClassDefFoundError).
> I think the result of the first check should be stored and reused.
> Here is the stacktrace (just to show the way tika is using commons-compress):
> org.apache.commons.compress.compressors.xz.XZUtils.isXZCompressionAvailable(XZUtils.java:52)
> 	at org.apache.commons.compress.compressors.CompressorStreamFactory.createCompressorInputStream(CompressorStreamFactory.java:140)
> 	at org.apache.tika.parser.pkg.ZipContainerDetector.detectCompressorFormat(ZipContainerDetector.java:95)
> 	at org.apache.tika.parser.pkg.ZipContainerDetector.detect(ZipContainerDetector.java:81)
> 	at org.apache.tika.detect.CompositeDetector.detect(CompositeDetector.java:61)



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