As discussed in https://github.com/openjdk/jdk/pull/510 there is never a reason to explicitly instantiate any instance of `Atomic*` class with its default value, i.e. `new AtomicInteger(0)` could be replaced with `new AtomicInteger()` which is faster: @State(Scope.Thread) @OutputTimeUnit(TimeUnit.NANOSECONDS) @BenchmarkMode(value = Mode.AverageTime) public class AtomicBenchmark { @Benchmark public Object defaultValue() { return new AtomicInteger(); } @Benchmark public Object explicitValue() { return new AtomicInteger(0); } } THis benchmark demonstrates that `explicitValue()` is much slower: Benchmark Mode Cnt Score Error Units AtomicBenchmark.defaultValue avgt 30 4.778 ± 0.403 ns/op AtomicBenchmark.explicitValue avgt 30 11.846 ± 0.273 ns/op So meanwhile https://bugs.openjdk.java.net/browse/JDK-8145948 is still in progress we could trivially replace explicit zeroing with default constructors gaining some performance benefit with no risk.
I've tested the changes locally, both tier1 and tier 2 are ok. Could one create an issue for tracking this? ------------- Commit messages: - 8255299: Drop explicit zeroing at instantiation of Atomic* objects Changes: https://git.openjdk.java.net/jdk/pull/818/files Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=818&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8255299 Stats: 19 lines in 17 files changed: 0 ins; 3 del; 16 mod Patch: https://git.openjdk.java.net/jdk/pull/818.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/818/head:pull/818 PR: https://git.openjdk.java.net/jdk/pull/818
