On Wed, 25 Apr 2012, Frank Shearar wrote:
On 25 April 2012 21:11, Levente Uzonyi <[email protected]> wrote:
On Fri, 20 Apr 2012, Frank Shearar wrote:
On 20 April 2012 03:51, Levente Uzonyi <[email protected]> wrote:
On Thu, 19 Apr 2012, Frank Shearar wrote:
I found a serious bug in parsing numbers with negative exponents. It
was completey broken, in fact, parsing 1e-1 as 10, not 1 / 10. Anyway.
This version fixes that, and adds a bunch of tests demonstrating that
number parsing will return rationals if it can.
It's significantly slower than Squeak's SqNumberParser:
Time millisecondsToRun: [100000 timesRepeat: [SqNumberParser parse:
'1234567890']] => 466
Time millisecondsToRun: [100000 timesRepeat: [PPSmalltalkNumberParser
parse: '1234567890']] => 32082
I've attached a MessageTally spying on the latter: I've not much skill
in reading these, but nothing leaps out at me as being obviously
awful.
Didn't check the code, just the tally, and I think that
PPSmalltalkNumberParser(PPSmalltalkNumberGrammar)>>digitsBase: is begging
for optimization. It's probably also the cause of the high amount of
garbage
which causes significant amount of time spent with garbage collection.
It's also interesting is that the finalization process does so much work,
there may be something wrong with your image.
Thanks for taking a look, Levente.
I'd expect digitsBase: to dominate the running costs, given that we're
parsing numbers.
I finally checked the code and there's plenty of space for optimization.
Note that the code can't be loaded into Squeak, because there's an invalid
symbol #__gen__binding, and some methods with nil category.
Indeed: you might recall I've mentioned some incompatibilities between
Pharo and Squeak where PetitParser is concerned: Symbol >> isBinary
doesn't exist, you MUST have Scanner prefAllowUnderscoreSelectors:
true and Scanner allowUnderscoreAsAssignment: false, you need to
fiddle with RB so you can load AST-Core and AST-Compiler, and so on.
It's _possible_ (I wrote/am writing the number grammar in a Squeak
image), and once I've addressed _this_ incompatibility, I'll address
the others!
I do make a large number of throwaway "immutable" values with a
Builder-like pattern... in PPSmalltalkNumberParser >>
#makeNumberFrom:base:. That, I would imagine, could explain the
garbage?
The current garbage collector is not optimal for large images and large
amount of garbage, so you should try avoid creating it in performance
critial parts of your code.
I foolishly forgot to add the message tally. You'll notice the absence
of the weak finalization process: that might have been because the
image predated the recent weak finalization thrashing fix.
I'm using Eliot's VMs and those don't include Igor's patch.
Levente
frank
If I may, what do you look for when reading the MessageTally? How do
you tell, for instance, that there's excessive garbage production?
In your tally GC time was 20% of total time and another 20% for the
finalization process. These numbers should be much lower, usually less than
1%.
That the incremental GCs take 7ms? (I'm reading Andreas' comments on
http://wiki.squeak.org/squeak/4210 again.)
7ms for an incremental GC is also a bit high, it should be around 1-2ms.
Levente
frank
Levente
frank
On 14 September 2011 20:26, Frank Shearar <[email protected]>
wrote:
On 3 September 2011 19:35, Nicolas Cellier
<[email protected]> wrote:
2011/9/3 Frank Shearar <[email protected]>:
On 3 September 2011 18:50, Lukas Renggli <[email protected]> wrote:
I think it is a good idea to have the number parser separate, after
all it might also make sense to use it separately.
It seems that the new Smalltalk grammar is significantly slower. The
benchmark PPSmalltalkClassesTests class>>#benchmark: that uses the
source code of the collection hierarchy and does not especially
target
number literals runs 30% slower.
Also I see that "Number readFrom: ..." is still used within the
grammar. This seems to be a bit strange, no?
Yes: it's a double-parse, which is a bit lame. First, we parse the
literal with PPSmalltalkNumberParser, which ensures that the thing
given to Number class >> #readFrom: is a well-formed token (so, in
particular, Squeak's Number doesn't get to see anything other than a
well-formed token).
It sounds like you're happy with the basic concept, so maybe I should
remove the Number class >> #readFrom: stuff, see if I can't remove
the
performance issues, and resubmit the patch.
frank
Yes, a NumberParser is essentially parsing, and this duplication
sounds
useless.
The main feature of interest in NumberParser that I consider a
requirement and should find its equivalence in a PetitNumberParser is:
- round a decimal representation to nearest Float
It's simple, just convert a Fraction asFloat in a single final step to
avoid cumulating round off errors - see
#makeFloatFromMantissa:exponent:base:
The second feature of interest in NumberParser is the ability to
parser LargeInteger efficiently by avoiding (10 * largeValue +
digitValue) loops, and replacing them with a log(n) cost.
This would be a simple thing to implement in a functional language.
Hopefully this won't offend your sensibilities too much :). It does,
in fact, use 10* loops - I wrote an experimental "front half * rear
half" recursion, which was slower in my benchmarks.
This version has the grammar and parser doing no string->number
conversion at all. PPSmalltalkNumberMaker supplies a number of utility
methods designed to stop one from making malformed numbers. It also
supplies a builder interface that the parser uses to construct
numbers.
frank
Nicolas
Lukas
On 3 September 2011 17:18, Frank Shearar <[email protected]>
wrote:
On 3 September 2011 15:56, Lukas Renggli <[email protected]> wrote:
On 3 September 2011 16:51, Frank Shearar <[email protected]>
wrote:
Hi Lukas,
I haven't :) mainly because I'm unsure where to put it - is there
perhaps a PP Inbox, or shall I just post the merged version, or
what's
your preference? (How about an mcd between my merge and PP's
head?)
Just put the .mcz at some public URL (dropbox, squeak source, ...)
or
attach it to a mail.
Ah, great - here it is. You'll see I've written the grammar as a
separate class. That was really more to make what I'd done more
obvious and to minimise the change to PPSmalltalkGrammar, but
perhaps
it's not a bad idea anyway: it's easy to see the number literal
subgrammar.
frank
Lukas
--
Lukas Renggli
www.lukas-renggli.ch
--
Lukas Renggli
www.lukas-renggli.ch
