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From Paul Elschot <>
Subject Re: Using MMapDirectory fails TestCompoundFile; MMapDirectory for huge indexes
Date Fri, 01 Oct 2004 20:53:29 GMT
On Friday 01 October 2004 22:16, Doug Cutting wrote:
> Paul Elschot wrote:
> > I'm working on a memory mapped directory that uses multiple buffers
> > for large files.
> Great!
> There will be a small performance hit, as each call to readByte() will
> need to first check whether it's overflowed the current buffer, right?

Yes. I just simplified that test to a counter equals zero.
That counter also is decremented by readByte().

> > While trying some test runs I found that the current version fails a
> > test:
> >
> >     [junit] Testsuite: org.apache.lucene.index.TestCompoundFile
> Thanks for testing this!

Errr, TestCompoundFile turns out to be quite extensive, so I'll share that 
with Dmitry.

> > I'm testing the version with multiple buffers using a smaller maximum
> > buffer size (1024 * 128), and it does this test in the same way.
> You mean it fails too?

Yes, it behaves in the same way. It also passes the remaining tests
from TestCompoundFile for a smaller maximum buffer size.

> > I have not yet looked into TestCompoundFile. When it is a good test
> > case for this, I'll submit the multibuffer version as an enhancement.
> Thanks, that would be great.

A new version of MMapDirectory is on it's way with
a few comments on possible performance improvements.

Paul Elschot

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