We have changes in jsr166 CVS ready for going into openjdk
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/HashMap-resize/index.html
(except for the microbenchmark, which doesn't fit into our pipeline at the
moment).
Pardon the fiddling ...
---
Let's check in this order:
+ while (s > threshold && table.length < MAXIMUM_CAPACITY)
---
Let's add more HashMap pseudo-methods to the test:
+
+ Object[] table(HashMap map) {
+ try {
+ return (Object[]) TABLE.get(map);
+ } catch (Throwable t) { throw new AssertionError(t); }
+ }
+
+ int capacity(HashMap map) {
+ return table(map).length;
+ }
and some more assertions:
+ @Test
+ public void capacityTest() {
+ HashMap<Integer, Integer> map = new HashMap<>();
+ assertNull(table(map));
+
+ map.put(1, 1);
+ assertEquals(capacity(map), 16);
+
+ map.putAll(IntStream.range(0, 64).boxed().collect(toMap(i ->
i, i -> i)));
+ assertEquals(capacity(map), 128);
+ }
I did my own TODO to randomize testBug8210280
On Mon, Dec 17, 2018 at 7:40 AM Michal Vala <mv...@redhat.com> wrote:
> All tests I've run passed, benchmarks show ~15% performance boost for
> putAllWithBigMapToNonEmptyMap.
>
> On 12/17/18 7:32 AM, Michal Vala wrote:
> > Hi,
> >
> > thanks Doug, this is nice reduction.
> >
> > Here's the new webrev:
> > http://cr.openjdk.java.net/~mvala/jdk/jdk/JDK-8210280/webrev.03/
> >
> > Just a nitpick, issue is in using linked-list in buckets. The same is
> used for
> > both HashMap and LinkedHashMap, so mentioning just LinkedHashMap might
> be
> > confising. I've updated the comment s/LinkedHashMap/linked-list buckets/.
> >
> > I'm just running tier1 tests and benchmarks.
> >
> > On 12/16/18 3:23 PM, Doug Lea wrote:
> >>
> >> On 12/14/18 1:37 AM, Michal Vala wrote:
> >>> Thanks Martin for finding this serious issue and the testcase.
> >>>
> >>
> >> Sorry that I wasn't paying attention to this and so forced Martin to
> >> discover the hard way that because of LinkeHashMap, you can't skip
> >> doubling steps (at least not without a lot of rework). Also, the
> >> documentation should have mentioned this. A simpler way to reduce
> >> overhead in the case at hand is just to loop in putMapEntries:
> >>
> >> --- HashMap.java.~1.9.~ 2018-11-11 15:43:24.982878495 -0500
> >> +++ HashMap.java 2018-12-16 09:05:48.924727867 -0500
> >> @@ -502,8 +502,13 @@
> >> if (t > threshold)
> >> threshold = tableSizeFor(t);
> >> }
> >> - else if (s > threshold)
> >> - resize();
> >> + else {
> >> + // Because of LinkedHashMap constraints, we cannot
> >> + // expand all at once, but can reduce total resize
> >> + // effort by repeated doubling now vs later
> >> + while (table.length < MAXIMUM_CAPACITY && s >
> threshold)
> >> + resize();
> >> + }
> >> for (Map.Entry<? extends K, ? extends V> e :
> m.entrySet()) {
> >> K key = e.getKey();
> >> V value = e.getValue();
> >>
> >
>
> --
> Michal Vala
> OpenJDK QE
> Red Hat Czech
>
