On Wed, 24 Jan 2024 20:40:36 GMT, Joshua Cao <d...@openjdk.org> wrote:
>> This change mirrors what we did for ConcurrentHashMap in >> https://github.com/openjdk/jdk/pull/17116. When we add all entries from one >> map to anther, we should resize that map to the size of the sum of both maps. >> >> I used the command below to run the benchmarks. I set a high heap to reduce >> garbage collection noise. >> >> java -Xms25G -jar benchmarks.jar -p size=100000 -p addSize=100000 -gc true >> org.openjdk.bench.java.util.HashMapBench >> >> >> Before change >> >> >> Benchmark (addSize) (mapType) (size) Mode Cnt Score >> Error Units >> HashMapBench.putAll 100000 HASH_MAP 100000 avgt 4 22.927 ± >> 3.170 ms/op >> HashMapBench.putAll 100000 LINKED_HASH_MAP 100000 avgt 4 25.198 ± >> 2.189 ms/op >> >> >> After change >> >> >> Benchmark (addSize) (mapType) (size) Mode Cnt Score >> Error Units >> HashMapBench.putAll 100000 HASH_MAP 100000 avgt 4 16.780 ± >> 0.526 ms/op >> HashMapBench.putAll 100000 LINKED_HASH_MAP 100000 avgt 4 19.721 ± >> 0.349 ms/op >> >> >> We see about average time improvements of 26% in HashMap and 20% in >> LinkedHashMap. >> >> --- >> >> In the worse case, we may have two maps with identical keys. In this case, >> we would aggressively resize when we do not need to. I'm also adding an >> additional `putAllSameKeys` benchmark. >> >> Before change: >> >> >> Benchmark (addSize) (mapType) >> (size) Mode Cnt Score Error Units >> HashMapBench.putAllSameKeys 100000 HASH_MAP >> 100000 avgt 6.956 ms/op >> HashMapBench.putAllSameKeys:gc.alloc.rate 100000 HASH_MAP >> 100000 avgt 1091.383 MB/sec >> HashMapBench.putAllSameKeys:gc.alloc.rate.norm 100000 HASH_MAP >> 100000 avgt 7968871.917 B/op >> HashMapBench.putAllSameKeys:gc.count 100000 HASH_MAP >> 100000 avgt ≈ 0 counts >> HashMapBench.putAllSameKeys 100000 LINKED_HASH_MAP >> 100000 avgt 8.417 ms/op >> HashMapBench.putAllSameKeys:gc.alloc.rate 100000 LINKED_HASH_MAP >> 100000 avgt 992.543 MB/sec >> HashMapBench.putAllSameKeys:gc.alloc.rate.norm 100000 LINKED_HASH_MAP >> 100000 avgt 8768892.941 B/op >> HashMapBench.putAllSameKeys:gc.count 100000 LINKED_HASH_MAP >> 100000 avgt ≈ 0 counts >> >> >> Af... > > Joshua Cao has updated the pull request incrementally with one additional > commit since the last revision: > > Add benchmark with all duplicate keys I added a commit to instead compute `max(size() + m.size(), size()`. Its not ideal to use a long here, because we can get stuck in the while loop. The threshold is an int, so if `s` is a long, it will always be bigger than the threshold. ------------- PR Comment: https://git.openjdk.org/jdk/pull/17544#issuecomment-1909146483
