Improve ArrayList and NodeList #396

lahma · 2023-08-10T07:23:06Z

I was checking how much faster it is to use span instead of indexing (Jint uses indexing at the moment) and I though that it shouldn't have that much difference as it had so tweaked code a bit.

better indexer with less IL - it's enough to have nameof(something) to cause ldstring, more fine-grained ThrowHelper to the rescue
encapsulate EnsureCapacity as single method to resize
remove TrimExcess as I didn't see much point in it performance wise

Results

Modified benchmark (no boxing for result) was used against both main and this PR. The couple byte allocations in 0 size test case ForLoopBenchmark is quite curious, but didn't find out the reason. Now indexing is as fast as spans or even faster for small lists (0-1), spans start to shine when iterating more items.

💡 We maybe should consider converting visitors to use foreach + span.


BenchmarkDotNet v0.13.7, Windows 11 (10.0.23516.1000)
AMD Ryzen 9 5950X, 1 CPU, 32 logical and 16 physical cores
.NET SDK 7.0.400
  [Host]     : .NET 6.0.21 (6.0.2123.36311), X64 RyuJIT AVX2
  DefaultJob : .NET 6.0.21 (6.0.2123.36311), X64 RyuJIT AVX2

Esprima.Benchmark.AstTreeWalkBenchmark

Diff	Method	Mean	Error	Allocated
Old	VisitChildren	2.565 ms	0.0151 ms	35 B
New		2.572 ms (0%)	0.0140 ms	35 B (0%)

Esprima.Benchmark.FileParsingBenchmark

Diff	Method	FileName	Mean	Error	Allocated
Old	ParseProgram	angular-1.2.5	10.231 ms	0.0621 ms	4095.44 KB
New			10.238 ms (0%)	0.0449 ms	4095.76 KB (0%)
Old	ParseProgram	backbone-1.1.0	1.348 ms	0.0018 ms	647.77 KB
New			1.329 ms (-1%)	0.0083 ms	647.8 KB (0%)
Old	ParseProgram	jquery-1.9.1	7.932 ms	0.0374 ms	3540.14 KB
New			7.997 ms (+1%)	0.0368 ms	3541.17 KB (0%)
Old	ParseProgram	jquery.mobile-1.4.2	12.138 ms	0.0350 ms	5609.22 KB
New			12.053 ms (-1%)	0.0513 ms	5609.56 KB (0%)
Old	ParseProgram	mootools-1.4.5	6.363 ms	0.0213 ms	2938.37 KB
New			6.377 ms (0%)	0.0284 ms	2938.73 KB (0%)
Old	ParseProgram	underscore-1.5.2	1.156 ms	0.0048 ms	555.5 KB
New			1.139 ms (-1%)	0.0046 ms	555.45 KB (0%)
Old	ParseProgram	yui-3.12.0	5.439 ms	0.0223 ms	2714.65 KB
New			5.476 ms (+1%)	0.0237 ms	2714.93 KB (0%)

Esprima.Benchmark.NodeListEnumerationBenchmark

Diff	Method	NodeListIndex	Mean	Error	Allocated
Old	For_DirectIndexing	0	5,633,143.177 ns	25,214.8469 ns	7 B
New		0	2,318,609.390 ns (-59%)	11,763.7113 ns	3 B (-57%)
Old	For_SpanIndexing	0	2,629,088.965 ns	3,468.6020 ns	3 B
New		0	2,619,675.417 ns (0%)	8,738.2733 ns	4 B (+33%)
Old	ForEach_Span	0	2,630,783.750 ns	7,398.6263 ns	3 B
New		0	2,698,511.576 ns (+3%)	50,837.2970 ns	3 B (0%)
Old	For_DirectIndexing	1	1,782.627 ns	1.1875 ns	0 B
New		1 (0%)	685.421 ns (-62%)	2.2029 ns	0 B
Old	For_SpanIndexing	1	669.814 ns	3.1510 ns	0 B
New		1 (0%)	673.555 ns (+1%)	0.1979 ns	0 B
Old	ForEach_Span	1	674.983 ns	0.6107 ns	0 B
New		1 (0%)	674.960 ns (0%)	4.5344 ns	0 B
Old	For_DirectIndexing	2	20.300 ns	0.1101 ns	0 B
New		2 (0%)	5.302 ns (-74%)	0.0018 ns	0 B
Old	For_SpanIndexing	2	4.746 ns	0.0197 ns	0 B
New		2 (0%)	4.704 ns (-1%)	0.0063 ns	0 B
Old	ForEach_Span	2	4.799 ns	0.0218 ns	0 B
New		2 (0%)	4.735 ns (-1%)	0.0129 ns	0 B

Esprima.Benchmark.VisitorBenchmark

Diff	Method	Mean	Error	Allocated
Old	Visit	11.54 ms	0.225 ms	14 B
New		10.49 ms (-9%)	0.103 ms	14 B (0%)
Old	Rewrite	23.60 ms	0.467 ms	28 B
New		22.46 ms (-5%)	0.157 ms	28 B (0%)

adams85 · 2023-08-10T09:56:03Z

src/Esprima/ArrayList.cs

+            if (value < (_items?.Length ?? 0))
            {
-                T[] array = new T[value];
-                if (_count > 0)
-                {
-                    Array.Copy(_items, 0, array, 0, _count);
-                }
-                _items = array;
-            }
-            else
-            {
-                _items = null;
+                ThrowArgumentOutOfRangeException(nameof(value), value, null);
            }

+            EnsureCapacity(value);


I'd stick to the original logic here because the change leads to a bit confusing API. For example:

var al = new ArrayList<int>(initialCapacity: 4); al.Capacity = 5; var c = al.Capacity;

c is 8 instead of 5, which is kinda unexpected after explicitly setting Capacity to 5 in the previous line. At least, BCL types like List<T> don't have such behavior.

Fair enough, I'll revert the capacity related changes.

I had problems with the Capacity property only, EnsureCapacity seemed ok in other places. But I'm also ok with the original logic.

src/Esprima/ArrayList.cs

src/Esprima/JavascriptParser.cs

src/Esprima/Scanner.RegExpParser.cs

src/Esprima/Scanner.cs

src/Esprima/ArrayList.cs

adams85 · 2023-08-10T10:44:10Z

samples/Esprima.Benchmark/NodeListEnumerationBenchmark.cs

@@ -30,7 +28,7 @@ public void Setup()
    }

    [Benchmark]
-    public object For_DirectIndexing()


Damn, nice oversight on my part... This pretty much messed up the benchmark results.

Nice catch! 👍

adams85 · 2023-08-10T10:54:06Z

Now indexing is as fast as spans or even faster for small lists (0-1), spans start to shine when iterating more items.

💡 We maybe should consider converting visitors to use foreach + span.

Sounds like it's worth a try. Thanks to our source generation magic, probably it wouldn't be too tedious. So, I'm looking forward to the new benchmark results! ;)

lahma · 2023-08-10T12:27:48Z

OK, I've reverted most of the PR and should now only contain the gist of indexing improvements. main vs this branch:

Esprima.Benchmark.NodeListEnumerationBenchmark

Diff	Method	Toolchain	Mean	Error	Allocated
Old	For_DirectIndexing	Default	5,839,201.953 ns	15,907.3791 ns	7 B
New		Default	2,683,663.854 ns (-54%)	6,805.3141 ns	3 B (-57%)
Old	For_SpanIndexing	Default	2,629,126.875 ns	9,483.2562 ns	4 B
New		Default	2,636,007.338 ns (0%)	3,330.0859 ns	4 B (0%)
Old	ForEach_Span	Default	2,634,116.172 ns	19,719.2877 ns	4 B
New		Default	2,626,229.010 ns (0%)	8,729.7299 ns	3 B (-25%)
Old	For_DirectIndexing	Default	1,776.865 ns	0.1620 ns	0 B
New		Default	682.067 ns (-62%)	0.7556 ns	0 B
Old	For_SpanIndexing	Default	683.543 ns	1.5607 ns	0 B
New		Default	672.859 ns (-2%)	0.8225 ns	0 B
Old	ForEach_Span	Default	686.167 ns	4.9590 ns	0 B
New		Default	666.897 ns (-3%)	0.5036 ns	0 B
Old	For_DirectIndexing	Default	18.818 ns	0.1431 ns	0 B
New		Default	4.997 ns (-73%)	0.0213 ns	0 B
Old	For_SpanIndexing	Default	4.758 ns	0.0104 ns	0 B
New		Default	4.390 ns (-8%)	0.0057 ns	0 B
Old	ForEach_Span	Default	4.756 ns	0.0056 ns	0 B
New		Default	4.405 ns (-7%)	0.0071 ns	0 B

* better indexer with less IL * encapsulate EnsureCapacity * remove TrimExcess

adams85 · 2023-08-10T15:27:12Z

FWIW, ReadOnlySpan<T> ctor does less checks than Span<T> ctor.

I assume that spans' worse performance for smaller lists is caused by the initial cost of constructing a span. So, for read-only iteration ReadOnlySpan<T> is a tiny bit better.

adams85

Those indexer perf gains are serious. Kudos!

lahma · 2023-08-10T17:04:44Z

Thanks for helping out and getting this finalized!

lahma requested a review from adams85 August 10, 2023 07:32

adams85 reviewed Aug 10, 2023

View reviewed changes

lahma force-pushed the improve-indexer branch from 9c1a019 to 5ac06b5 Compare August 10, 2023 11:58

lahma requested a review from adams85 August 10, 2023 12:28

lahma added 2 commits August 10, 2023 15:30

Improve ArrayList and NodeList

d555a06

* better indexer with less IL * encapsulate EnsureCapacity * remove TrimExcess

revert capacity related changes

f33827c

lahma force-pushed the improve-indexer branch from 5ac06b5 to f33827c Compare August 10, 2023 12:30

adams85 approved these changes Aug 10, 2023

View reviewed changes

lahma merged commit 3e71c85 into sebastienros:main Aug 10, 2023
2 checks passed

lahma deleted the improve-indexer branch August 10, 2023 17:04

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Improve ArrayList and NodeList #396

Improve ArrayList and NodeList #396

lahma commented Aug 10, 2023 •

edited

Loading

adams85 Aug 10, 2023

lahma Aug 10, 2023

adams85 Aug 10, 2023

adams85 Aug 10, 2023

adams85 commented Aug 10, 2023

lahma commented Aug 10, 2023

adams85 commented Aug 10, 2023 •

edited

Loading

adams85 left a comment

lahma commented Aug 10, 2023

Improve ArrayList and NodeList #396

Improve ArrayList and NodeList #396

Conversation

lahma commented Aug 10, 2023 • edited Loading

Results

Esprima.Benchmark.AstTreeWalkBenchmark

Esprima.Benchmark.FileParsingBenchmark

Esprima.Benchmark.NodeListEnumerationBenchmark

Esprima.Benchmark.VisitorBenchmark

adams85 Aug 10, 2023

Choose a reason for hiding this comment

lahma Aug 10, 2023

Choose a reason for hiding this comment

adams85 Aug 10, 2023

Choose a reason for hiding this comment

adams85 Aug 10, 2023

Choose a reason for hiding this comment

adams85 commented Aug 10, 2023

lahma commented Aug 10, 2023

Esprima.Benchmark.NodeListEnumerationBenchmark

adams85 commented Aug 10, 2023 • edited Loading

adams85 left a comment

Choose a reason for hiding this comment

lahma commented Aug 10, 2023

lahma commented Aug 10, 2023 •

edited

Loading

adams85 commented Aug 10, 2023 •

edited

Loading