On 12/21/2012 05:49 PM, Chris Hegarty wrote:
Updated webrev/specdiff:
http://cr.openjdk.java.net/~chegar/8003981/ver.01/
I also included 'webrev_diffAgainstVer00', so you can easily see the
differences against the last webrev.
Note: I remove any reference to the threshold,MIN_ARRAY_SORT_GRAN, in
the API, given the other comments on this change.
Remi,
Thank you for the detailed review.
Chris,
all is green for me, thumb up.
[...]
> In all Sorter, instead of calling Arrays.sort(), you should call
> DualPivotQuicksort.sort to avoid unnecessary range checks.
Yes, I see your point. The implementation note in the spec says
Arrays.sort, but I think this suggestion is good. I made the change,
and since DualPivotQuicksort.sort is inclusive of toIndex/right -1
from toIndex/right.
good catch !
[...]
-Chris.
Rémi
On 12/21/2012 11:19 AM, Remi Forax wrote:
On 12/20/2012 06:31 PM, Chris Hegarty wrote:
This is a review request for the addition of utility methods to
java.util.Arrays that provide sorting of arrays in parallel, JEP 103
[1].
Webrev:
http://cr.openjdk.java.net/~chegar/8003981/ver.00/
Current sorting implementations provided by the Java Collections
Framework (Collections.sort and Arrays.sort) all perform the sorting
operation sequentially in the calling thread. This enhancement will
offer the same set of sorting operations currently provided by the
Arrays class, but with a parallel implementation that utilizes the
Fork/Join framework. These new API’s are still synchronous with regard
to the calling thread as it will not proceed past the sorting
operation until the parallel sort is complete.
The actual sorting API this proposal adds will leverage the
ForkJoinPool.commonPool (default Fork/Join pool defined as part of JEP
155). The sorting algorithm is that used in Doug Lea’s ParallelArray
implementation.
This work was originally done over in the lambda/lambda repo by David
Holmes, and is now being cleaned up and brought into jdk8.
Open issues/differences from version in lambda:
1) Is is necessary for MIN_ARRAY_SORT_GRAN to be in the public API?
It is an implementation detail (easy to remove).
2) The use of FJP.commonPool is an implementation detail, not
part of the spec. Should not be a problem, just worth pointing
out, as it differs from what is in lambda/lambda.
-Chris.
[1] http://openjdk.java.net/jeps/103
Hi Chris,
in Arrays.parallelSort(TYPE[] a, int fromIndex, int toIndex),
there is no need to have the two supplementary local variable origin and
fence,
ws is not a great better name (workspaceArray?), I had to read the code
of ArraySortHelpers to understand.
ArraySortHelpers should be renamed to ArrayParallelSortHelpers.
In ArraySortHelpers, all Sorter, Merger, etc. should declare only one
field by line, currently, the formatting of the fields is weird.
In all Sorter, instead of calling Arrays.sort(), you should call
DualPivotQuicksort.sort to avoid unnecessary range checks.
In compute() of Sorter and Merger, you should copy a and w in local
variables (a = this.a) to help the VM to figure out that they never
changed,
it will also reduce the bytecode size.
In Sorter.compute, n should be loaded in a local field,
int l = origin;
int g = gran;
int n = this.n;
In Merger.compute, the sequence of inits before the second while
should be:
int l = lo;
int lFence = l + nleft; // instead of lo + nleft
int r = ro;
int rFence = r + nright; // instead of ro + nright
int k = wo;
it should not changed the performance but it's more inline with the
coding style of the rest of the code IMO.
cheers,
Rémi
