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From Erick Erickson <erickerick...@gmail.com>
Subject Re: Performance StringCoding.decode
Date Tue, 05 Aug 2014 16:16:39 GMT
Well, that code is when you're reading the fields of documents off disk.
Stored fields are compressed/decompressed automatically.

So one question is what is your test doing? In other words, is it
artificially hitting this? The theory is that this should only be done when
you gather the final top N docs to return to the user (i.e. for each doc in
the &rows= parameter if you were coming in from Solr).

There's no simple configuration setting to turn off compression that I know
of. Then again, at the Lucene level I'm pretty clueless.

Erick


On Tue, Aug 5, 2014 at 8:41 AM, dizh@neusoft.com <dizh@neusoft.com> wrote:

> how to monitor? use jprofile?
>
>
>
>
>
> From: Sascha Janz
> Date: 2014-08-05 22:36
> To: java-user@lucene.apache.org
> Subject: Performance StringCoding.decode
> hi,
>
> i want to speed up our search performance. so i run test and monitor them
> with java mission control.
>
> the analysis showed that one hotspot is
>
>
> sun.nio.cs.UTF_8$Decoder.decode(byte[], int, int, char[])
> - java.lang.StringCoding.decode(Charset, byte[], int, int)
>    - java.lang.String.<init>(byte[], int, int, Charset)
>
>  -org.apache.lucene.codecs.compressing.CompressingStoredFieldsReader.readField(DataInput,
>       StoredFieldVisitor, FieldInfo, int)
>
> -org.apache.lucene.codecs.compressing.CompressingStoredFieldsReader.visitDocument(int,
>        StoredFieldVisitor)
>        -org.apache.lucene.index.SegmentReader.document(int,
> StoredFieldVisitor)
>         -org.apache.lucene.index.IndexReader.document(int, Set)
>
> we use jdk 1.7.55 and lucene 4.9.0.
>
> is there a chance to speed this up? or do some changes in lucene
> IndexWriterConfig, e.g. use an other codec?
>
> we use the default values of IndexWriterConfig
>
>
> regards
> sascha
>
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