Yet another way to iterate over a collection. Coming in via jsr166 soon.
Seeing CopyOnWriteArrayList beat ArrayList decisively suggests that
optimizing it is defintely worth doing.
And of course the numbers below contain more low-hanging fruit if anyone
still cares about the performance of LinkedList or Vector.
Have you considered adding public ranged methods on Arrays? We currently
only have the "deranged" Arrays.hashCode(Object[])
--- IteratorMicroBenchmark.java 9 May 2018 17:43:01 -0000 1.44
+++ IteratorMicroBenchmark.java 11 May 2018 18:18:37 -0000
@@ -34,6 +34,7 @@
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.ArrayDeque;
+import java.util.Arrays;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
@@ -562,6 +563,12 @@
for (int i = 0; i < iterations; i++) {
sum[0] = 0;
x.replaceAll(sneakyAdder);
- check.sum(sum[0]);}}});
+ check.sum(sum[0]);}}},
+ new Job(klazz + " hashCode") {
+ public void work() throws Throwable {
+ int hashCode = Arrays.hashCode(x.toArray());
+ for (int i = 0; i < iterations; i++) {
+ if (x.hashCode() != hashCode)
+ throw new AssertionError();}}});
}
}
C2:
Method Millis Ratio
ArrayList hashCode 94 1.000
ArrayList$SubList hashCode 97 1.031
LinkedList hashCode 92 0.974
AbstractList$SubList hashCode 111 1.172
Vector hashCode 82 0.866
SynchronizedRandomAccessList hashCode 97 1.022
CopyOnWriteArrayList hashCode 8 0.091
COWSubList hashCode 8 0.090
C1:
Method Millis Ratio
ArrayList hashCode 112 1.000
ArrayList$SubList hashCode 118 1.060
LinkedList hashCode 118 1.054
AbstractList$SubList hashCode 276 2.472
Vector hashCode 126 1.132
SynchronizedRandomAccessList hashCode 293 2.620
CopyOnWriteArrayList hashCode 37 0.330
COWSubList hashCode 36 0.325
