Gambit-list Juin 2007

gambit-list@iro.umontreal.ca

19 participants
20 discussions

Edge triggered I/O with libevent
by Adam Langley 04 Avr '13

04 Avr '13

Gambit uses the select call on POSIX systems to multiplex IO operations. This is fine for small numbers of file descriptors, but falls apart quickly with large numbers[1]. libevent[2] is a wrapper library around a number of modern IO multiplexing systems (epoll on Linux, kqueue on the BSDs as well as poll and select). Attached is a patch which converts Gambit to using edge triggered I/O with epoll and libevent. This also requires a patch (attached) of libevent since the standard distribution doesn't include edge triggering support and the upstream appears to be on holiday. (epoll is required because I don't have a BSD box on which to develop edge triggering support for kqueue) This patch (for Gambit) preprocesses away to nothing unless --enable-libevent is passed to the configure script. (Note that, since this patches the configure.ac script, you'll need to run autoconf to regenerate). I hope I've not broken anything, but at this stage I've only tested that the console and tcp ports work. This patch (in the future) should also allow people, who write programs which use socket calls directly, to integrate into the main event loop at some point. Testing is more than welcome and, if you find a form of IO which is broken, please email me. [1] http://monkey.org/~provos/libevent/libevent-benchmark2.jpg [2] http://monkey.org/~provos/libevent/ -- Adam Langley agl(a)imperialviolet.org http://www.imperialviolet.org (+44) (0)7906 332512 PGP: 9113 256A CC0F 71A6 4C84 5087 CDA5 52DF 2CB6 3D60

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Please don't delete the .c file
by Bradley Lucier 06 Fév '08

06 Fév '08

Marc: I needed to debug a gsc-compiled file with gdb today, and it was fairly inconvenient that the .c file wasn't left around by compile- file in beta 21. I suggest that the .c file be left around for the various source tools that need it. Brad

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Re: [gambit-list] compiler bug?
by Marc Feeley 03 Sep '07

03 Sep '07

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 25-Sep-06, at 3:48 PM, Sven.Hartrumpf(a)FernUni-Hagen.de wrote: > Hello Marc. > > I have a large program which behaves a little different > with gsc than any other Scheme I know of (bigloo, chicken, gauche): > Here is the problematic region: > > (let* ((orth (and (pair? word-info) > ;(not (eq? (caar word-info) 'words)) > (fs-value (car word-info) '(orth)))) > (orth-l (if orth (string-length orth) 0)) > (left-hyphen (and (> orth-l 2) > (char=? (string-ref orth 0) # > \-))) ; examples: \quw{Steuergesetzgebung und -verwaltung}, \quw > {auspringen und -setzen} > (right-hyphen (and (> orth-l 1) > (char=? (string-ref orth (- orth- > l 1)) #\-))) > (step (if left-hyphen > (and (not right-hyphen) > -1) > (and right-hyphen > 1)))) > > left-hyphen and right-hyphen are evaluated to #f for some binding - > this > is as expected. But step is bound to 1 which seems wrong to me. > Minimizing the problem might be hard for me, so I hope that you can > see > the problem already :-) > > Ciao > Sven Sven, you have just uncovered a nasty bug in the compiler. In beta 18 the transformation for the "and" form is too aggressive in the case where the second argument is a constant. As far as I can tell this bug was introduced just before beta 18 was released. Surprisingly in the 70Kloc in the Gambit runtime system and compiler this case does not occur. I have now fixed the bug and will release beta 19 shortly because this is a serious bug. Thanks! Marc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (Darwin) iD8DBQFFGEqS//V9Zc2T/v4RAqTeAJ9asp7elGoK7yqa6MzmLFTRj6K8UwCfc3d4 5haROCNvlgMs1NREyZCgYIw= =bvLI -----END PGP SIGNATURE-----

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Gambit installers
by Marc Feeley 03 Aoû '07

03 Aoû '07

Does anyone have experience creating installers for Windows and MacOS X? What are the best free installers? Marc

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Does gambit-c have call/ec?
by naruto canada 27 Jui '07

27 Jui '07

hi Does gambit-c have call/ec? Thanks.

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Re: [gambit-list] problem with load.
by Marc Feeley 20 Jui '07

20 Jui '07

On 20-Jun-07, at 12:49 AM, naruto canada wrote: > On 6/19/07, Marc Feeley <feeley(a)iro.umontreal.ca> wrote: >> >> On 19-Jun-07, at 9:59 AM, naruto canada wrote: >> >> > gambit-c seems to have problem with "load". >> > I was able to load a test file 26meg with petite and mzscheme, but >> > crashes gambit-c. (gsi) >> >> By "crash" do you mean a segment violation or a "heap overflow" >> message? > > I think it's just out of memory, "top" showing fast increasing > memory usage. If it didn't output a "heap overflow" message, my guess is that Gambit is still computing but with such a large heap that it is very slow due to thrashing. > >> >> By my calculations it will require roughly 500 MB of RAM to load a 26 > > I think it takes more than 500M, I have 1G of memory, and the program > crashes before loading. You might be able to avoid thrashing on your machine by specifying a maximum heap size with the -:hXXX option. My test on a 1GB RAM machine seems to indicate that loading the 26MB file of integer sequences generates a peak of about 630MB of live data. So this should work: gsi -:h700000 test.scm To get the heap usage (live data, etc), do: gsi -:h700000 -e '(gc-report-set! #t)' test.scm > I know the problem can be got around by simply doing "cat code.sc| > gsi". > I don't know if it's possible to treat "load" simply as another input > stream like petite or mzscheme. No. Gambit's model is that files loaded by "load" are complete "modules". The module has to be parsed (to check for lexical and syntax errors) and macro-expanded before it can execute. This is so loading an interpreted file has (roughly) the same semantics as loading a compiled file. > > What if someone needs to write to test cases, based on the execution > of a large file then gambit-c won't be able handle it "in-code" sorta > speak, it has to "cat" the test case after "code.sc", just not pretty > but workable. anyway, it's not a serious problem. I think a better approach is to treat the sequences as "data". Then you just need a small driver program that does: (define (go) (with-input-from-file "sequences.dat" (lambda () (let loop () (let ((s (read))) (if (not (eof-object? s)) (begin (solve-seq s) (loop)))))))) (go) Marc

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Re: [gambit-list] problem with load.
by Marc Feeley 19 Jui '07

19 Jui '07

On 19-Jun-07, at 9:59 AM, naruto canada wrote: > gambit-c seems to have problem with "load". > I was able to load a test file 26meg with petite and mzscheme, but > crashes gambit-c. (gsi) By "crash" do you mean a segment violation or a "heap overflow" message? By my calculations it will require roughly 500 MB of RAM to load a 26 meg source code file using "load". The whole program must be read as a single "begin" expression, and then that expression is passed to the evaluator. > the file has no code really, just repeatedly set! and call a > function like: > the file has all the integer sequence from : > http://www.research.att.com/~njas/sequences/index.html > > the way petite and mzscheme did it was like treating the file as input > from console > (I guess), while gambit-c maybe trying to load it into memory? You can get the same thing with Gambit using the -:d- option, i.e.: % gsi -:d- < big-file.scm It will be like typing each expression in the file at the REPL (which is semantically slightly different in the handling of macros, which are "local" to a file in Gambit when the file is "loaded"). Marc

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Gambit Readtables
by Guillaume Cartier 18 Jui '07

18 Jui '07

I am trying to have my reatable recognize extra named chars like #\Home, #\End, ... but there's something I don't get... In the following code: ---------------------- (include "~~/src/lib/header.scm") (define extra-named-chars '(("Nul" . #\x00) ("Home" . #\x01) ("Enter" . #\x03) ("End" . #\x04))) (define (add-extra-named-chars! readtable) (macro-readtable-named-char-table-set! readtable (append (macro-readtable-named-char-table readtable) extra-named-chars))) (define (make-my-readtable) (let ((readtable (##readtable-copy ##main-readtable))) (add-extra-named-chars! readtable) readtable)) (define (tr) (add-extra-named-chars! ##main-readtable)) (define (tr2) (set! ##main-readtable (make-my-readtable))) ---------------------- If I do (tr) then everything works perfectly, but using tr2 doesn't work, I get Invalid '#\' name: "End" Any clue? Thanks, Guillaume Cartier

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Newbie Question: define-syntax and syntax-rules
by Gabriel Kronberger 17 Jui '07

17 Jui '07

Hi, This is probably a silly question but I'm having major troubles with define-syntax or syntax-rules. I used to work with the gambit debian packages version 4.0b20 however it seems the necessary files (syntax-case.scm ...) are missing from the package. So I complied and installed 4.0b22. Now I can load the syntax-case.scm file however it seems I can't get a simple syntax definition to work. Even the simple example from the Gambit-C documentation doesn't work. Gambit Version 4.0 beta 22 > (load "~~syntax-case") "/usr/local/Gambit-C/4.0b22/syntax-case.scm" >(define-syntax unless (syntax-rules () ((unless test body ...) (if test #f (begin body ...))))) *** ERROR IN (console(a)3.15 -- Ill-formed expression Unfortunately i couldn't find information on this problem in the documentation or the archives so i'm kinda stuck now. Any help is appreciated. Thanks, Gabriel

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Profiling scheme + C programs
by Phil Dawes 15 Jui '07

15 Jui '07

Hi Gambit List, I've got a gambit program which includes some C code for searching memory mapped files and I was wondering how best to profile it. I've used statprof, but since it works using gambit interrupts it doesn't statistically highlight time spent in functions containing C code. I've been using a 'define-timed' macro I wrote (see below) which records the accumulated wall-time a function uses. This is fine, but it means you have to instrument each function manually (by changing '(define (foo) ..) to '(define-timed (foo) ..)' which is a bit sucky. Could this be modified to instrument each function automatically? (I tried redefining 'define' but couldn't get this to work cleanly) Is there a better way? Many thanks, Phil --------- (define *timerhash* (make-table)) (define (reset-timer) (set! *timerhash* (make-table))) (define (accum-time name thunk) (let* ((timebefore (real-time)) (res (thunk))) (table-set! *timerhash* name (+ (table-ref *timerhash* name 0) (- (real-time) timebefore))) res)) (define (get-times) (map (lambda (e) (set! total (+ total (cdr e))) (cons (car e) (* 1000 (cdr e)))) (sort-list (table->list *timerhash*) (lambda (a b) (> (cdr a) (cdr b)))))) (define-syntax define-timed (syntax-rules () ((define-timed (name . args) body ...) (define (name . args) (accum-time 'name (lambda () body ...))) ))) -------- Usage: (define-timed (myfunction) (do stuff)) (reset-timer) ;...do stuff (myfunction) ;... (get-times)

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Gambit-list Juin 2007