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From "Uwe Schindler (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (LUCENE-2824) optimizations for bufferedindexinput
Date Sun, 19 Dec 2010 12:27:01 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-2824?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12972975#action_12972975
] 

Uwe Schindler edited comment on LUCENE-2824 at 12/19/10 7:26 AM:
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And as said in my above comment, for buffer sizes like 1024 or in that area (even for 16384
or like that), the overhead of throwing the AIOOBE would be much higher (as the JVM needs
to generate stack trace!!!). I would simply don't even think about that *g*.

For MMap the idea is fine because we normally have "buffer" sizes of 2^31th, where the AIOOBE
/ BufferUnderflowEx is veeeeeeeeeeeery seldom.

      was (Author: thetaphi):
    And as said in my above comment, for buffer sizes like 1024 or in that are (even for 16384
or like that), the overhead of throwing the AIOOBE would be much higher (as the JVM needs
to generate stack trace!!!). I would simply don't even think about that *g*.

For MMap the idea is fine because we normally have "buffer" sizes of 2^31th, where the AIOOBE
/ BufferUnderflowEx is veeeeeeeeeeeery seldom.
  
> optimizations for bufferedindexinput
> ------------------------------------
>
>                 Key: LUCENE-2824
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2824
>             Project: Lucene - Java
>          Issue Type: Improvement
>    Affects Versions: 3.1, 4.0
>            Reporter: Robert Muir
>         Attachments: LUCENE-2824.patch
>
>
> along the same lines as LUCENE-2816:
> * the readVInt/readVLong/readShort/readInt/readLong are not optimal here since they defer
to readByte. for example this means checking the buffer's bounds per-byte in readVint instead
of per-vint.
> * its an easy win to speed this up, even for the vint case: its essentially always faster,
the only slower case is 1024 single-byte vints in a row, in this case we would do a single
extra bounds check (1025 instead of 1024)

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