[concurrency-interest] Strange behaviour when sorting an uniform array

Lukas Krecan lukas.krecan at gmail.com
Wed May 26 03:09:01 EDT 2010


Thanks a lot, I really appreciate what you are doing.

On 05/25/2010 10:38 PM, Doug Lea wrote:
> On 05/25/10 03:07, Lukas Krecan wrote:
>> Hi,
>>     I have been playing with extra166y library and found that when I try
>> to sort an uniform array (full of ones) it takes ages.
>
> Thanks for reporting this! As correctly guessed by Kasper, this
> was due to a degenerate O(n^2) case in the sequential leaf sort.
> Sorry for the problems. I changed a few things to allow
> replacement for long and double versions with calls to  Arrays.sort
> which as of jdk7 includes much faster base sorts that also
> avoid this degeneracy. So if you run these with openjdk7
> snapshots, the parallel sorts will also be faster. Also,
> the other variants of sort (with comparators and for objects)
> are changed to also screen for runs of identical values.
>
> Get replacements at the usual places:
>
> # API specs:  http://gee.cs.oswego.edu/dl/jsr166/dist/extra166ydocs/
> # jar file: http://gee.cs.oswego.edu/dl/jsr166/dist/extra166y.jar 
> (compiled using Java6 javac).
> # Browsable CVS sources: 
> http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/extra166y/
>
>
>
>
>
>
>
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