Fast and cheap (Double|Float)::toString Java algorithm

[Suminda Sirinath Salpitikorala Dharmasena]

Hello,

I hope everything is well with you.

Due to other commitments this work has stalled.

I was planning to implement:
- fast to string conversion
- fast string parsing
- fast formatting
- fast search
- fast sort
- fast templating
- fast buffers

The code I have done so far is here: https://github.com/sirinath/moby

Wondering if someone can take this forward until I have more time in my
hand.

Suminda

On Sat, 6 Feb 2021 at 09:50, Suminda Sirinath Salpitikorala Dharmasena <
sirinath1978m at gmail.com> wrote:

> Hello,
>
> I am working on a port of DragonBox to Java. If there is interest in
> contributing this is most welcome.
>
> Suminda
>
> On Fri, 5 Feb 2021 at 21:51, Raffaello Giulietti <
> raffaello.giulietti at gmail.com> wrote:
>
>> Hello,
>>
>> as a reminder, a Java implementation of Schubfach [1] intended to
>> replace the current slow and expensive OpenJDK (Double|Float)::toString
>> algorithm has been discussed, presented and contributed to this mailing
>> list in several posts. The last implementation is available in pre-Skara
>> webrev form, as referenced in [2]. On my laptop hardware, the speedup
>> factor is 17.7x wrt OpenJDK.
>>
>>
>>
>> Recently, Alexander Bolz translated Schubfach to C++ for the purpose of
>> comparing the performance of several bin2dec floating-point numbers
>> algorithms [3].
>>
>> In the meantime, Junekey Jeon implemented and perfected his own
>> Dragonbox in C++, a new algorithm based on Schubfach [4]. From [5]: "In
>> addition to the core idea of Schubfach, Dragonbox utilizes some
>> Grisu-like ideas to minimize the number of expensive 128-bit × 64-bit
>> multiplications, at the cost of having more branches and
>> divisions-by-constants."
>>
>> In the C++ ecosystem, Schubfach has been the fastest known algorithm
>> before being gently pushed aside by Dragonbox, as can be seen in the
>> graphs in [3].
>>
>>
>>
>> While developing Schubfach back in 2018, I experimented myself with
>> blending core Schubfach with my own earlier algorithm similar to Grisu.
>> However, probably due to uncontrollable JIT compilation behavior, I
>> could not observe any benefit. On the contrary, I measured performance
>> drops probably because of the added complexity, which is public enemy
>> nr. 1 for JIT compilers. Therefore, I opted for the simpler current
>> design that seemed more suitable for (the then 2018 version of) C2.
>>
>>
>>
>> I hope this can somehow revive this community's interest and confidence
>> toward Schubfach to definitely supplant the current expensive
>> (Double|Float)::toString algorithm.
>>
>>
>> Greetings
>> Raffaello
>>
>> ----
>>
>> [1] https://drive.google.com/open?id=1luHhyQF9zKlM8yJ1nebU0OgVYhfC6CBN
>> [2]
>>
>> https://mail.openjdk.java.net/pipermail/core-libs-dev/2020-March/065297.html
>> [3] https://github.com/abolz/Drachennest
>> [4] https://github.com/jk-jeon/dragonbox
>> [5]
>> https://github.com/jk-jeon/dragonbox/blob/master/other_files/Dragonbox.pdf
>>
>