Faster HashMap implementation
alex14n at gmail.com
Sat Jul 25 00:04:54 UTC 2009
On Wed, Jul 22, 2009 at 8:21 PM, Doug Lea<dl at cs.oswego.edu> wrote:
> On further evaluating it (among other possible HashMap replacements),
> I'm not convinced that they are enough better to commit.
> Size: ... 9216 36864 147456 589824
> HashMap ... 45 97 208 273
> V2 ... 40 78 188 257
Gain +12% +24% +11% +6%
More than 10% average improvement on big maps,
not worse on tiny maps, less memory usage - not a bad result imho
> Similarly for the mixed-side-array approach of Alex's Compact/Fast HashMap.
My version is a chained map, not an open map,
So concerns about locality and hit rates does not apply.
And with defragmentation there is not so many cache misses on collisions.
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