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From Michael McCandless <>
Subject Re: NIO.2
Date Sat, 28 Mar 2009 16:26:56 GMT
I think having async IO will be great, though I wonder how we would
change Lucene to take advantage of it.  It ought to gain us
concurrency (eg we can score last chunk while we have an io request
out to retrieve next chunk, of term docs / positions / etc.).

Watch service sounds neat.  Maybe we could use that as a way for
readers to know when to reopen themselves.

Something Lucene would really benefit from is access to madvise, so
that we could tell the OS that the massive amounts of data we are
reading & writing for merging should not be cached.  But it doesn't
look like NIO2 has exposed this...

Another thing would be control over the priority of multiple
outstanding IO tasks.  EG I'd like to say that the IO in a merge
thread is lower priority than indexing thread, which is lower priority
than searching threads.  This is even further out (I don't think OSs
expose this control?).


On Sat, Mar 28, 2009 at 9:44 AM, Michael Busch <> wrote:
> NIO.2 sounds great.
> Though, it will probably take a pretty long time before we can switch Lucene
> to Java 1.7 :(
> We could write a (contrib) module that we don't ship together with the core
> that has a Directory implementation which uses NIO.2.
> -Michael

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