Gambit-list Novembre 2008

gambit-list@iro.umontreal.ca

22 participants
21 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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Interactive 3D graphics with Gambit-C
by Alex Sandro Queiroz e Silva 06 Jan '10

06 Jan '10

Hallo, I am thinking about doing some basic 3D graphics with Gambit-C. Although I am sure code generated by Gambit-C is fast enough[1], I am a bit worried about the garbage collector. What's the type of garbage collector used by Gambit? If it kicks in during interactive rendering, should I expect annoying pauses? [1] - http://www.ventonegro.org/2008/09/the-need-for-speed/ -alex http://www.ventonegro.org/

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I/O puzzle...
by Marc Feeley 09 Jui '09

09 Jui '09

Puzzle... what's the bug in the following code? See end of message for answer. (define http-server-start! (lambda (hs stop?) (let ((server-port (open-tcp-server (list port-number: (server-port-number hs) backlog: 128 reuse-address: #t server-address: '#u8(127 0 0 1) ; on localhost interface only char-encoding: 'ISO-8859-1)))) (input-port-timeout-set! server-port 3) (accept-connections hs server-port stop?)))) (define accept-connections (lambda (hs server-port stop?) (let loop () (let ((connection (read server-port))) (if (eof-object? connection) (if (stop?) (close-input-port server-port) (loop)) (begin (if (server-threaded? hs) (let ((dummy-port (open-dummy))) (parameterize ((current-input-port dummy-port) (current-output-port dummy-port)) (thread-start! (make-thread (lambda () (serve-connection hs connection)))))) (serve-connection hs connection)) (loop))))))) . . . . . . . . Answer: the (input-port-timeout-set! server-port 3) is at the wrong place. It sets a timeout ***3 seconds in the future***. So after 3 seconds have passed all calls to read in accept-connections will not block (and lead to a tight, CPU intensive loop). The correct approach is to put the call to (input-port-timeout-set! server-port 3) just before the call to read. Puzzle #2: why did Gambit chose to define timeouts that are not relative to the moment that an I/O function is called? Marc

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location of libgambcgsi.so
by Marijn Schouten (hkBst) 01 Déc '08

01 Déc '08

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi list, which line of configure.ac or one of the makefile.in's determines what the exact path, as given by the first line of output of the command "readelf -d /usr/bin/gsi", is at which the executable gsi searches for libgambcgsi.so in the case that gambit has been configured with --enable-shared? Thanks, Marijn - -- Marijn Schouten (hkBst), Gentoo Lisp project, Gentoo ML <http://www.gentoo.org/proj/en/lisp/>, #gentoo-{lisp,ml} on FreeNode -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkkvUS0ACgkQp/VmCx0OL2xLvACgsfu1/jL9knChwRm6Mm+0sDk/ f0oAoIR9xtjtgiZNiXB4BOBsRX3Reval =bk9I -----END PGP SIGNATURE-----

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Adding docs to wiki?
by Ali 30 Nov '08

30 Nov '08

Hi there, I'm new to Gambit and it looks like an excellent bit of software. I was wondering whether or not it would be a good idea to copy the docs onto the wiki system. I'd be more than happy to copy the text across and wiki format it if desired. As I see it this would have the usual benefits of a wiki, but the disadvantage of having 2 copies of the docs which need to be synchronised. What do you think? Would such a move bring more disadvantages than advantages? Ali

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Termite, IO and memory leakage
by Nicholas Walton 30 Nov '08

30 Nov '08

Hi, I have a large Termite based system that runs over eight cores on OS X Leopard. The system distributes itself over as many Termite processes as are made available and each process may make use of anyother. However, I have been getting odd segmentation errors occurring. I have shrunk the code down to the framework built on top of Termite and a small example (as below) (define (stress-test n m) (mapn (lambda(i) (dpmap-split (lambda (i) (length (dpmap-split (lambda(j) (+ j j)) ; (newline) (write j)) (make-integer-list (+ 1 i)) next-slave 'INNER-STRESS (lambda(x)#t))) (thread-sleep! m)) (make-integer-list 100) next-slave 'OUTER-STRESS (lambda(x)#t))) n)) The interface to Termiote is through dpmap-split which acts as a distributed form of map by partitioning the calls from map over the slaved Termite instances, via remote-spawn. Executing (stress-test 1000 0) termintates as expected. I have logging code in dpmap-split which writes to the terminal's for all the processes with no problem. However if I replace the (+ j j) call with (newline) (write j)) then after a while (stress-test 1000 0) fails with a segmentation violation, having until then written to each instance's terminal the values as I would expect. Termite appears to have a problem with IO within spawned processes. Secondly, even with (+ j j) in place it gobbles up core as if there is no tommorrow. By the time (stress-test 10000 0) completes using three instances, each instance has nearly 1Gig allocated. This is causing me considerable problems with the development system that relies on Termite to support its computational requirements and runs for hours at a time making many hundreds of call to Termite via dpmap-split. The interface dpmap-split is side effect free. I have patched Termite's make-tag function to return a string instead of an interned symbol, and traced string->symbol to ensure that interned symbols are not building garbage up, but still Termite devours huge amounts of core. Any ideas please? Nick Walton

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[ANN] Gambit-C v4.3.2 released
by gambit＠iro.umontreal.ca 27 Nov '08

27 Nov '08

1 0

Debugging macros...?
by David St-Hilaire 27 Nov '08

27 Nov '08

Hi all! Is there a way to debug a macro expansion? More precisely, I'd like to be able to have access to the full debugger when my macro expansion fails such that I could trace what's wrong of the code producing the expansion... At the moment I get something like: > (pp (lambda () (define-class tata (toto) (slot: a)))) *** ERROR -- Unbound table key (table-ref '#<table #2> 'tata) > with no possibility to debug and see whats wrong. I guess that the environment is available at the expansion time so I don't see why I couldn't debug it like normal gambit code. Many thanks in advance ^_^Y David

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Thank you for Gambit
by Arthur Smyles 27 Nov '08

27 Nov '08

In the US, our Thanksgiving holiday is coming up. It's a good time to take stock on what to be thankful for. I just wanted to thank all of you for your contributions to the Gambit source code and just as important, the Gambit community. I've really enjoyed programming with it and studying it. I'd also like the thank all the people who contribute questions and answers on this mailing list. I've found them really enlightening at times. Arthur

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Re: [gambit-list] Termite, IO and memory leakage
by Nicholas Walton 26 Nov '08

26 Nov '08

Christian et al, I ran it under gdb having rebuilt gsi / gsc with --debug and without. Little difference in either case. The attached files form the framework with the exception of the SLIB library of utilty functions. The output from gdb is in gdbout.Ran the code compiled and interpreted with no noted difference. Nick On Tuesday, November 25, 2008, at 05:59PM, "Christian Jaeger" <christian(a)pflanze.mine.nu> wrote: >Christian Jaeger wrote: >> Your best bet (short of someone going to debug it for you) really is >> running Gambit under gdb and see where it crashes. Just run "gdb gsc" >> and from there load your program as usual (assuming you're using, or >> know how to use, |compile-file| and |load| for your programs), or "gdb >> yourlinkedprogram" or "gdb gsi-script" or whatever. Then "run >> eventualprogramarguments" then "backtrace" when it crashed. > >PS. I once wrote a script named "with-gdb-backtrace-to" which makes >running apps under gdb trivial, I've now put it up here: > >http://repo.or.cz/w/with-gdb-backtrace-to.git?a=blob_plain;f=with-gdb-backt… >http://repo.or.cz/w/with-gdb-backtrace-to.git > >Christian. > > >

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Gambit-list Novembre 2008