LinkedList => use when adds total more than reads
ArrayList => use when reads total more than adds.
ArrayList => use when reads total more than adds.
But even then, I'm pretty sure Go actually uses an array for it's green stacks nowadays, even while paying the copy penalty for expansion.
I've also written a a video processor around that time too that was bottle necked using ArrayLists - typically a decode, store and read once op. It was at this point I looked at other collections, other list implementations and blocking deques (ArrayList was the wrong collection type to use, but I'd been in a rush for MVP) and ultimately came across https://github.com/conversant/disruptor and used that instead.
The ArrayList Vs Linkedlist was a real eye opener for me in two different systems this same behaviour was replicated when using ArrayLists like queues or incorrect sizing of the buffer increments as load increases.
Anyway, I felt I had to run the benchmarks myself.
@Benchmark
@Fork(1)
@BenchmarkMode(Mode.Throughput)
@OutputTimeUnit(TimeUnit.SECONDS)
public Object arrayListPreallocAddMillionNulls() {
ArrayList<Object> arrList = new ArrayList<>(1048576);
for (int i = 0; i <= 1_000_000; i++) {
arrList.add(null);
}
return arrList;
}
@Benchmark
@Fork(1)
@BenchmarkMode(Mode.Throughput)
@OutputTimeUnit(TimeUnit.SECONDS)
public Object arrayListAddMillionNulls() {
ArrayList<Object> arrList = new ArrayList<>();
for (int i = 0; i <= 1_000_000; i++) {
arrList.add(null);
}
return arrList;
}
@Benchmark
@Fork(1)
@BenchmarkMode(Mode.Throughput)
@OutputTimeUnit(TimeUnit.SECONDS)
public Object linkedListAddMillionNulls() {
LinkedList<Object> linkList = new LinkedList<>();
for (int i = 0; i <= 1_000_000; i++) {
linkList.add(null);
}
return linkList;
}
JDK8
Benchmark Mode Cnt Score Error Units
MyBenchmark.arrayListAddMillionNulls thrpt 5 229.950 ± 9.994 ops/s
MyBenchmark.arrayListPreallocAddMillionNulls thrpt 5 344.116 ± 7.070 ops/s
MyBenchmark.linkedListAddMillionNulls thrpt 5 199.446 ± 15.910 ops/s
JDK17
Benchmark Mode Cnt Score Error Units
MyBenchmark.arrayListAddMillionNulls thrpt 5 90.462 ± 18.576 ops/s
MyBenchmark.arrayListPreallocAddMillionNulls thrpt 5 214.079 ± 15.505 ops/s
MyBenchmark.linkedListAddMillionNulls thrpt 5 216.796 ± 19.392 ops/s
This helps prove my point that adds (and deletes) are generally faster by default when not pre sizing, or removing.
Typically (in my experience) ArrayLists are used without thought to sizing, often because initial capacity and amount to resize, cannot be determined sensibly or consistently.
If in your example you were also to resize the lists, (perhaps adding then dropping those in the Fibonacci sequence?), it would help prove my statement further.
Certainly not worth the -2 points I got from making the statement, but hey you can "please some people some of the time..." :D