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
