On Thu, 17 Mar 2022 21:10:14 GMT, Marius Hanl <mh...@openjdk.org> wrote:
> This simple PR optimizes the observable `ArrayList` creation by using the
> ArrayList constructor/array size so that the underlying array will be
> initialized at the correct size which will speed up the creation as the array
> does not need to grow as a result of the `addAll` call.
>
> I also added tests which will succeed before and after to verify that nothing
> got broken by this change.
> Also I made a benchmark test. Results:
>
> | Benchmark | Mode| Cnt | Score | Error | Units
> | ------------- | ------------- | ------------- | ------------- |
> ------------- | ------------- |
> | ListBenchmark OLD | thrpt | 25 | 722,842 | ± 26,93 | ops/s
> | ListBenchmark NEW | thrpt | 25 | 29262,274 | ± 2088,712 | ops/s
>
> Edit: I also made a synthetic benchmark by measuring the same code below 100
> times with `System.nanoTime`.
> ListBenchmark OLD (avg): 21-23ms
> ListBenchmark NEW (avg): 2 ms
>
> <details><summary>Benchmark code</summary>
>
>
> import javafx.collections.FXCollections;
> import javafx.collections.ObservableList;
> import org.openjdk.jmh.annotations.Benchmark;
> import org.openjdk.jmh.annotations.Scope;
> import org.openjdk.jmh.annotations.Setup;
> import org.openjdk.jmh.annotations.State;
> import org.openjdk.jmh.annotations.TearDown;
>
> import java.util.ArrayList;
> import java.util.List;
>
> @State(Scope.Benchmark)
> public class ListBenchmark {
>
> List<String> strings;
>
> @Setup
> public void setup() {
> strings = new ArrayList<>();
> for(int i = 0; i< 100000;i++) {
> strings.add("abc: " + i);
> }
> }
>
> @TearDown
> public void tearDown() {
> strings = null;
> }
>
> @Benchmark
> public ObservableList<String> init() {
> return FXCollections.observableArrayList(strings);
> }
> }
>
>
> </details>
This pull request has now been integrated.
Changeset: b3eca1f6
Author: Marius Hanl <mh...@openjdk.org>
Committer: Kevin Rushforth <k...@openjdk.org>
URL:
https://git.openjdk.org/jfx/commit/b3eca1f64977343c06e6035fab385935055b6d6b
Stats: 49 lines in 2 files changed: 41 ins; 4 del; 4 mod
8283346: Optimize observable ArrayList creation in FXCollections
Reviewed-by: mstrauss, nlisker, kcr
-------------
PR: https://git.openjdk.org/jfx/pull/758
