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From Christopher O'Connell <>
Subject Concurrent Trees
Date Mon, 09 Nov 2009 21:41:45 GMT
On Nov 9, 2009, at 14:01, Paul Davis <>  
> In trunk the computation and index writing are split to take up to two
> cores. It'd be theoretically possible to expand the mapping side to
> use all available cores but most reports say that the btree writing
> process is CPU bound, so any more than a single mapper would just be a
> waste of resources.
> Unfortunately, parallelizing the btree updates is rather non-trivial.
> I've contemplated a few different methods for attempting it, but
> nothing that has come of my limited self amusement in that respect.
> HTH,
> Paul Davis

Dear Paul,

I'm willing to help work on this, however, as you note, truely  
concurrent updates to a tree are hard. I've been playing with subtree  
locking, but 1) it doesn't work right now and 2) the root is still  
temporarily locked, although it does generally reduce bottlenecks  

I've been reading about highly concurrent trees, I'll send some links  
when I get home.

~ Christopher

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