On Fri, 19 Mar 2021 19:40:13 GMT, Chris Plummer <[email protected]> wrote:
>> Koichi Sakata has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> Fix the sort bug for huge bytes in jhisto
>
> I see another cast-to-int related bug, and it's visible in your jhisto output
> (both before and after):
>
> 304: 1 16 jdk.internal.perf.Perf
> 305: 1 16 java.util.jar.JavaUtilJarAccessImpl
> 306: 254 2863336944 int[]
> Total : 22803 -1430650672
>
> The large `int[]` array should be at the top of the list, not the bottom. The
> issue is in ObjectHistogramElement.java:
>
> public int compare(ObjectHistogramElement other) {
> return (int) (other.size - size);
> }
>
> So this will result in the returned value having the wrong sign if the
> difference between `other.size` and `size` is too large. In
> ObjectHistogram.java, just above the code you fixed, we have:
>
> public List<ObjectHistogramElement> getElements() {
> List<ObjectHistogramElement> list = new ArrayList<>();
> list.addAll(map.values());
> Collections.sort(list, new Comparator<>() {
> public int compare(ObjectHistogramElement o1, ObjectHistogramElement
> o2) {
> return o1.compare(o2);
> }
> });
> return list;
> }
> So it looks like this is calling the buggy `compare()` method. I think the
> fix is to have `compare()` return -1, 0, or 1 depending on the `long` value
> of `(other.size - size)`, rather than just trying to return `(other.size -
> size)`.
@plummercj That is right! I fixed that bug and pasted the latest output of
jhisto to the body. Of course I re-ran the jtreg test.
-------------
PR: https://git.openjdk.java.net/jdk/pull/3087
