PetitParser performance

Hey all, thanks for the report, I will have a look at it asap.

Cheers Jan

Hey,

I was not aware about some exponential element in the overall complexity, it is strange and I will investigate it. Thank you Usman, for pointing this out.

In general, it is hard to add features into the PetitParser and preserve performance.

Therefore, we work on a tool, that will take PetitParser, analyze it and generates faster parser. The idea is to use PetitParser while developing the grammar and than generate a fast parser for "real" use. We hope we will be present the tool during the next ESUG.

Cheers,

Jan

On 20 February 2015 at 17:47, Usman Bhatti <[hidden email]> wrote:

I executed the script that I shared earlier in this thread and I see a considerable performance improvement in the latest version of PP. The attached chart shows the comparison chart between PP v 1.51 (green) with the newer version (red). For shorter strings (i.e. to the left on x-axis), the execution time is almost comparable to the previous version of PetitParser that dates before changes introduced by Jan. 

However, when I take the new version and parse the code source of larger code bases, the execution time still get a hit. For example, parsing 100K lines takes almost twice longer. The increase is exponential with even larger ones. That is consistent with results we see in the graph (the larger the chain to be parsed i.e. going from left to right in the x-axis, the higher the performance penalty). Meaning I still prefer the older version.

What will be good is to prepare some benches with Java Parser in PP, as it is open source, and a set of programs (e.g. ArguUML) that can serve as a standard to test execution time for PP that we can run as a jenkins service.

 

regards.

On Fri, Feb 20, 2015 at 9:09 AM, Tudor Girba <[hidden email]> wrote:

Great news.

@Usman: could you check?

Doru

On Fri, Feb 20, 2015 at 9:04 AM, Jan Kurš <[hidden email]> wrote:

Hey all, Please note that a new version in of PetitParser (JanKurs-271) should improve performance roughly comparable to the original performance. On my computer, I got improvement from 3900ms to 1300ms.

Cheers,

Jan

On 1 February 2015 at 22:55, Jan Kurš <[hidden email]> wrote:

Hey all, thanks for the report, I will have a look at it asap.

Cheers Jan

On 1 Feb 2015 20:55, "Usman Bhatti" <[hidden email]> wrote:

On Fri, Jan 30, 2015 at 9:36 PM, Sven Van Caekenberghe <[hidden email]> wrote:

Usman, this is a really cool bug report !

Thanks :)

 

> On 30 Jan 2015, at 16:36, Usman Bhatti <[hidden email]> wrote:
>
> Here is a script that shows the factor of 2 in time taken for parsing. The idea of the script is to introduce several wrong branches before hitting the correct one (originally proposed by Guillaume).
>
> |rule wrongBranches|
> [wrongBranches := (25 to: 45) inject: 24 asCharacter asParser into: [:acc :each | acc / each asCharacter asParser].
> rule := PPDelegateParser new.
> rule setParser: $a asParser / ((wrongBranches / $. asParser), rule).
> rule parse: (String  streamContents: [ :s |
>       30000 timesRepeat: [s nextPut: $.]. s nextPut: $a ])] timeToRun
>
>
> Below are the graphs that were generated when varying the string length provided to the above parser description. Green part shows the time taken by the older version and the red part with the latest PP.
>
> <graph.png>

>
> Data values and graph generated by the script in the attached file.
>
> regards.
>
> usman
>
> On Fri, Jan 30, 2015 at 1:30 PM, Tudor Girba <[hidden email]> wrote:
> Hi,
>
> Hmm. I thought this was fixed and that you said at the end that the performance penalty is no longer a factor of 2.
>
> Do you have a simple example for checking the simple case of 2x performance loss?
>
> Doru
>
>
> On Fri, Jan 30, 2015 at 12:28 PM, Usman Bhatti <[hidden email]> wrote:
> Hi,
>
> Since the work on the integration of PPContext in PetitParser, there is significant performance degradation. I have already mentioned that on simple grammar the factor is about 2. But on complex grammar (for example, our proprietary parser for 4D language ), we have seen that degradation is goes well beyond this factor. So, for example, for 800K lines that we parse in under 10 minutes without PPContext work, with the latest version it goes beyond 2h.
>
> I have not been able to reproduce my case on simple grammars. May be we can have some benchmarks using open source parsers and large code bases (e.g. PP Java Parser on JHotDraw or ArgoUML).
>
> Currently, I circumvent this issue by using PP v1.51 but I can provide relevant feedback and run benches on any improvements.
>
> regards.
>
> Usman
>
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