Hi Levente,


thanks for the hint. I see #primUTCMicrosecondClock is more efficient, but do we really want to risk a clock wrap here (integer overflow)?


Best,

Christoph


________________________________
Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im Auftrag von Levente Uzonyi <leves at caesar.elte.hu>
Gesendet: Mittwoch, 4. September 2019 18:55:59
An: squeak-dev at lists.squeakfoundation.org
Betreff: Re: [squeak-dev] The Inbox: ShoutCore-ct.71.mcz

Hi Christoph,

On Tue, 3 Sep 2019, commits at source.squeak.org wrote:

> A new version of ShoutCore was added to project The Inbox:
> http://source.squeak.org/inbox/ShoutCore-ct.71.mcz
>
> ==================== Summary ====================
>
> Name: ShoutCore-ct.71
> Author: ct
> Time: 3 September 2019, 2:20:09.991948 pm
> UUID: 2635dce1-6bda-3a4d-a726-3f66bb7c6431
> Ancestors: ShoutCore-ul.68
>
> Use TimeStamps instead of deprecated #primUTCMicrosecondClock.

In my understanding, TimeStamp is something we have been keeping around,
because it's used for printing method timestamps, but for any other
purpose there's its superclass: DateAndTime.
With some effort, I think we could and should deprecate TimeStamp.

#primUTCMicrosecondClock is still very useful, even though DateAndTime
instances are not initialized with it anymore.
For example, this primitive has the smallest overhead[1] to measure
runtime with microsecond resolution, which is exactly what the method
SHParserST80 class >> #benchmark uses it for.

I mentioned it in an earlier mail that I intend to undeprecate it, and add
the missing primitive 243 as well, which can be used to tell the VM to
flush its time zone offset cache.

Levente

[1] It's a numbered primitive with no arguments returning an Integer. On
64-bits, that integer will stay a SmallInteger for quite a while, so
there's no overhead on the image side to invoke it.

>
> =============== Diff against ShoutCore-ul.68 ===============
>
> Item was changed:
>  ----- Method: SHParserST80 class>>benchmark (in category 'benchmarking') -----
>  benchmark
>
>        | methods methodCount totalTime averageTime min median percentile80 percentile95 percentile99 max |
>        Smalltalk garbageCollect.
>        methods := OrderedCollection new: 100000.
>        CurrentReadOnlySourceFiles cacheDuring: [
>                | parser |
>                parser := SHParserST80 new.
>                SystemNavigation default allSelectorsAndMethodsDo: [ :class :selector :method |
>                        | source start ranges |
>                        source := method getSource asString.
> +                      start := TimeStamp now.
> -                      start := Time primUTCMicrosecondClock.
>                        ranges := parser
>                                rangesIn: source
>                                classOrMetaClass: class
>                                workspace: nil
>                                environment: nil.
> +                      methods addLast: { (TimeStamp now - start) asMicroSeconds. method. ranges size } ] ].
> -                      methods addLast: { Time primUTCMicrosecondClock - start. method. ranges size } ] ].
>        methods sort: #first asSortFunction.
>        methodCount := methods size.
>        totalTime := methods detectSum: #first.
>        averageTime := (totalTime / methodCount) rounded.
>
>        min := methods first.
>        median := methods at: methodCount // 2.
>        percentile80 := methods at: (methodCount * 0.8) floor.
>        percentile95 := methods at: (methodCount * 0.95) floor.
>        percentile99 := methods at: (methodCount * 0.99) floor.
>        max := methods last.
>        ^'
>        Methods         {1}
>        Total                   {2}ms
>        Average         {3}ms
>        Min                             {4}ms {5} range(s) ({6})
>        Median                  {7}ms {8} ranges ({9})
>        80th percentile {10}ms {11} ranges ({12})
>        95th percentile {13}ms {14} ranges ({15})
>        99th percentile {16}ms {17} ranges ({18})
>        Max                     {19}ms {20} ranges ({21})' format: ({
>                methodCount asString.
>                totalTime.
>                averageTime.
>                min first.
>                min third asString.
>                min second reference.
>                median first.
>                median third asString.
>                median second reference.
>                percentile80 first.
>                percentile80 third asString.
>                percentile80 second reference.
>                percentile95 first.
>                percentile95 third asString.
>                percentile95 second reference.
>                percentile99 first.
>                percentile99 third asString.
>                percentile99 second reference.
>                max first.
>                max third asString.
>                max second reference } replace: [ :each |
>                        each isNumber
>                                ifTrue: [ (each / 1000) printShowingDecimalPlaces: 3 ]
>                                ifFalse: [ each ] ])!

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