[Webkit-unassigned] [Bug 271610] Web Inspector: Generating JS builtins for createInspectorInjectedScript is very slow

Tue Apr 2 01:36:18 PDT 2024

https://bugs.webkit.org/show_bug.cgi?id=271610

--- Comment #4 from Karl Dubost <karlcow at apple.com> ---
TLDR
As a starting reference, on my laptop, I get:
16.54s user 0.04s system 99% cpu 16.715 total

but most of that time is used by one file: InjectedScriptSource.js, if I remove it I get:
0.93s user 0.02s system 97% cpu 0.973 total

More details:

_parse_functions is relatively fast for most of the iterations, but indeed InjectedScriptSource.js is one of the bottlenecks. Large file.

This is used here. 
https://searchfox.org/wubkat/rev/473ca5f8512b88edd7e82c8783e7e09158f17ba1/Source/JavaScriptCore/Scripts/wkbuiltins/builtins_model.py#215-217

It chokes only on one iteration. Replacing the code by:

        import time
        tic = time.perf_counter()
        parsed_functions = self._parse_functions(text)
        toc = time.perf_counter()
        print(f"_parse_functions: {toc - tic:0.4f}s / {filename} / {len(text)} chars")

The number of matches is given by length(matches) on 

        matches = [func for func in functionHeadRegExp.finditer(text)]

nb of matches: 6 / _parse_functions: 0.0461s / ArrayConstructor.js / 7841 chars
nb of matches: 2 / _parse_functions: 0.0053s / ArrayIteratorPrototype.js / 3003 chars
nb of matches: 34 / _parse_functions: 0.1062s / ArrayPrototype.js / 25784 chars
nb of matches: 8 / _parse_functions: 0.0278s / AsyncFromSyncIteratorPrototype.js / 6395 chars
nb of matches: 3 / _parse_functions: 0.0063s / AsyncFunctionPrototype.js / 2819 chars
nb of matches: 21 / _parse_functions: 0.0587s / AsyncGeneratorPrototype.js / 11595 chars
nb of matches: 1 / _parse_functions: 0.0001s / AsyncIteratorPrototype.js / 1460 chars
nb of matches: 3 / _parse_functions: 0.0009s / FunctionPrototype.js / 2042 chars
nb of matches: 4 / _parse_functions: 0.0081s / GeneratorPrototype.js / 3878 chars
nb of matches: 1 / _parse_functions: 0.0003s / GlobalObject.js / 1676 chars
nb of matches: 1 / _parse_functions: 0.0017s / GlobalOperations.js / 1985 chars
nb of matches: 2 / _parse_functions: 0.0109s / InternalPromiseConstructor.js / 3159 chars
nb of matches: 4 / _parse_functions: 0.0046s / IteratorHelpers.js / 3598 chars
nb of matches: 1 / _parse_functions: 0.0001s / IteratorPrototype.js / 1447 chars
nb of matches: 1 / _parse_functions: 0.0056s / MapConstructor.js / 2614 chars
nb of matches: 2 / _parse_functions: 0.0024s / MapIteratorPrototype.js / 2331 chars
nb of matches: 1 / _parse_functions: 0.0016s / MapPrototype.js / 1902 chars
nb of matches: 20 / _parse_functions: 0.0521s / ModuleLoader.js / 24361 chars
nb of matches: 1 / _parse_functions: 0.0003s / NumberConstructor.js / 1588 chars
nb of matches: 2 / _parse_functions: 0.0066s / ObjectConstructor.js / 3223 chars
nb of matches: 18 / _parse_functions: 0.0780s / PromiseConstructor.js / 13018 chars
nb of matches: 29 / _parse_functions: 0.0746s / PromiseOperations.js / 21115 chars
nb of matches: 3 / _parse_functions: 0.0078s / PromisePrototype.js / 3204 chars
nb of matches: 5 / _parse_functions: 0.0203s / ProxyHelpers.js / 5748 chars
nb of matches: 4 / _parse_functions: 0.0018s / ReflectObject.js / 2801 chars
nb of matches: 13 / _parse_functions: 0.2080s / RegExpPrototype.js / 22590 chars
nb of matches: 1 / _parse_functions: 0.0091s / RegExpStringIteratorPrototype.js / 2694 chars
nb of matches: 2 / _parse_functions: 0.0018s / SetIteratorPrototype.js / 2219 chars
nb of matches: 9 / _parse_functions: 0.0362s / SetPrototype.js / 9197 chars
nb of matches: 4 / _parse_functions: 0.0049s / ShadowRealmPrototype.js / 3285 chars
nb of matches: 1 / _parse_functions: 0.0038s / StringConstructor.js / 2200 chars
nb of matches: 1 / _parse_functions: 0.0082s / StringIteratorPrototype.js / 2588 chars
nb of matches: 29 / _parse_functions: 0.0356s / StringPrototype.js / 13145 chars
nb of matches: 2 / _parse_functions: 0.0283s / TypedArrayConstructor.js / 4428 chars
nb of matches: 14 / _parse_functions: 0.0224s / TypedArrayPrototype.js / 9332 chars
nb of matches: 2 / _parse_functions: 0.0005s / WebAssembly.js / 1725 chars
nb of matches: 20 / _parse_functions: 15.9046s / InjectedScriptSource.js / 62229 chars

Let's see inside:

        matches = [func for func in functionHeadRegExp.finditer(text)]
is not the bottleneck.

matches perf: 0.0002s / matches: 6
matches perf: 0.0001s / matches: 2
matches perf: 0.0010s / matches: 34
matches perf: 0.0002s / matches: 8
matches perf: 0.0001s / matches: 3
matches perf: 0.0004s / matches: 21
matches perf: 0.0000s / matches: 1
matches perf: 0.0000s / matches: 3
matches perf: 0.0001s / matches: 4
matches perf: 0.0000s / matches: 1
matches perf: 0.0000s / matches: 1
matches perf: 0.0001s / matches: 2
matches perf: 0.0001s / matches: 4
matches perf: 0.0000s / matches: 1
matches perf: 0.0000s / matches: 1
matches perf: 0.0000s / matches: 2
matches perf: 0.0000s / matches: 1
matches perf: 0.0004s / matches: 20
matches perf: 0.0000s / matches: 1
matches perf: 0.0001s / matches: 2
matches perf: 0.0004s / matches: 18
matches perf: 0.0007s / matches: 29
matches perf: 0.0001s / matches: 3
matches perf: 0.0002s / matches: 5
matches perf: 0.0000s / matches: 4
matches perf: 0.0006s / matches: 13
matches perf: 0.0001s / matches: 1
matches perf: 0.0000s / matches: 2
matches perf: 0.0003s / matches: 9
matches perf: 0.0001s / matches: 4
matches perf: 0.0000s / matches: 1
matches perf: 0.0000s / matches: 1
matches perf: 0.0004s / matches: 29
matches perf: 0.0001s / matches: 2
matches perf: 0.0003s / matches: 14
matches perf: 0.0000s / matches: 2
matches perf: 0.0020s / matches: 20

Ah found the thing which takes time is the return statement. 

        tuc = time.perf_counter()
        print(f"before list(map): {tuc - tic:0.8f}s")
        thingtoreturn = list(map(BuiltinFunction.fromString, functionStrings))
        tec = time.perf_counter()
        print(f"before return: {tec - tic:0.8f}s")
        return thingtoreturn

We get 

----
matches perf: 0.00086213s / matches: 6
after for loop: 0.00204904s
before list(map): 0.00206413s
before return: 0.10147529s
----
matches perf: 0.00015438s / matches: 2
after for loop: 0.00035775s
before list(map): 0.00036813s
before return: 0.01159988s
----
matches perf: 0.00195908s / matches: 34
after for loop: 0.00354625s
before list(map): 0.00356558s
before return: 0.17573083s
----
matches perf: 0.00039850s / matches: 8
after for loop: 0.00065675s
before list(map): 0.00066321s
before return: 0.03363075s
----
matches perf: 0.00006025s / matches: 3
after for loop: 0.00013025s
before list(map): 0.00013296s
before return: 0.00832750s
----
matches perf: 0.00067088s / matches: 21
after for loop: 0.00126525s
before list(map): 0.00127637s
before return: 0.08663021s
----
matches perf: 0.00000875s / matches: 1
after for loop: 0.00003654s
before list(map): 0.00004133s
before return: 0.00020388s
----
matches perf: 0.00005858s / matches: 3
after for loop: 0.00018046s
before list(map): 0.00020887s
before return: 0.00143387s
----
matches perf: 0.00019867s / matches: 4
after for loop: 0.00035454s
before list(map): 0.00036325s
before return: 0.00981967s
----
matches perf: 0.00001000s / matches: 1
after for loop: 0.00002362s
before list(map): 0.00002583s
before return: 0.00036204s
----
matches perf: 0.00005350s / matches: 1
after for loop: 0.00012946s
before list(map): 0.00013804s
before return: 0.00283438s
----
matches perf: 0.00006054s / matches: 2
after for loop: 0.00014371s
before list(map): 0.00014733s
before return: 0.01643325s
----
matches perf: 0.00015025s / matches: 4
after for loop: 0.00038112s
before list(map): 0.00039075s
before return: 0.00595804s
----
matches perf: 0.00002438s / matches: 1
after for loop: 0.00005275s
before list(map): 0.00005858s
before return: 0.00020354s
----
matches perf: 0.00006971s / matches: 1
after for loop: 0.00013025s
before list(map): 0.00013554s
before return: 0.00682037s
----
matches perf: 0.00004017s / matches: 2
after for loop: 0.00008846s
before list(map): 0.00009133s
before return: 0.00295483s
----
matches perf: 0.00002750s / matches: 1
after for loop: 0.00007175s
before list(map): 0.00007696s
before return: 0.00219413s
----
matches perf: 0.00042275s / matches: 20
after for loop: 0.00098187s
before list(map): 0.00098813s
before return: 0.05855404s
----
matches perf: 0.00001100s / matches: 1
after for loop: 0.00005625s
before list(map): 0.00006233s
before return: 0.00034088s
----
matches perf: 0.00013438s / matches: 2
after for loop: 0.00021438s
before list(map): 0.00021813s
before return: 0.00783958s
----
matches perf: 0.00047179s / matches: 18
after for loop: 0.00107554s
before list(map): 0.00108154s
before return: 0.08648308s
----
matches perf: 0.00065763s / matches: 29
after for loop: 0.00149079s
before list(map): 0.00151117s
before return: 0.07941017s
----
matches perf: 0.00006600s / matches: 3
after for loop: 0.00018075s
before list(map): 0.00020383s
before return: 0.00815983s
----
matches perf: 0.00017421s / matches: 5
after for loop: 0.00040908s
before list(map): 0.00042392s
before return: 0.02092254s
----
matches perf: 0.00005058s / matches: 4
after for loop: 0.00010371s
before list(map): 0.00011133s
before return: 0.00197779s
----
matches perf: 0.00065625s / matches: 13
after for loop: 0.00158467s
before list(map): 0.00159621s
before return: 0.21502942s
----
matches perf: 0.00005500s / matches: 1
after for loop: 0.00012642s
before list(map): 0.00012967s
before return: 0.00934592s
----
matches perf: 0.00003154s / matches: 2
after for loop: 0.00007296s
before list(map): 0.00007908s
before return: 0.00186450s
----
matches perf: 0.00027429s / matches: 9
after for loop: 0.00065712s
before list(map): 0.00066079s
before return: 0.03788817s
----
matches perf: 0.00006625s / matches: 4
after for loop: 0.00014829s
before list(map): 0.00015296s
before return: 0.00489046s
----
matches perf: 0.00003221s / matches: 1
after for loop: 0.00008021s
before list(map): 0.00008400s
before return: 0.00396992s
----
matches perf: 0.00005129s / matches: 1
after for loop: 0.00012296s
before list(map): 0.00012596s
before return: 0.00840154s
----
matches perf: 0.00042504s / matches: 29
after for loop: 0.00095896s
before list(map): 0.00096475s
before return: 0.03761792s
----
matches perf: 0.00010217s / matches: 2
after for loop: 0.00024237s
before list(map): 0.00024500s
before return: 0.02967329s
----
matches perf: 0.00025683s / matches: 14
after for loop: 0.00061087s
before list(map): 0.00061604s
before return: 0.02288504s
----
matches perf: 0.00001508s / matches: 2
after for loop: 0.00003850s
before list(map): 0.00004042s
before return: 0.00047821s
----
matches perf: 0.00228304s / matches: 20
after for loop: 0.00531071s
before list(map): 0.00531458s
before return: 15.74802542s

So the 
      list(map(BuiltinFunction.fromString, functionStrings))

is the thing to improve.

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