armedbear-devel January 2011

armedbear-devel@common-lisp.net

17 participants
32 discussions

[armedbear-devel] Another error message enhancement request
by Blake McBride 15 Jan '11

15 Jan '11

I just got the following error: #<THREAD "http-8084-1" {41ABA945}>: Unhandled condition of type SIMPLE-ERROR: The method has the wrong number of required arguments for the generic function. Which method? I have a macro that creates many, many methods. If it gave me the method name I'd be able to track the problem easily. I am embedding ABCL in a very large web application. Starting and stopping the server takes a significant amount of time, and I have no command line access to the code. Giving me the name of the method in question could save me 30 minutes easily. Thanks. Blake McBride

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[armedbear-devel] Error condition is too strong
by Blake McBride 14 Jan '11

14 Jan '11

Greetings, I am in the process of embedding ABCL into a web server application I have. While it is okay for an error to either be caught and handled, or not handled and having the thread terminate, it definitely is not okay for an error condition to kill the entire server. I am executing a (load "file") command (where "file" doesn't exist) from Java and it kills the entire server. I tried enclosing it in a try/catch block (I tried Exception & Throwable) and it still killed the server. I then replaced the load with (without a try/catch): File file = null; file.canRead(); And the error didn't kill the server. I just got a backtrace and the thread ended. (I think the error was caught higher up.) Is ABCL calling System.exit() or doing something similar? Thanks. Blake McBride

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[armedbear-devel] Alex Muscar wants to stay in touch on LinkedIn
by Alex Muscar 14 Jan '11

14 Jan '11

LinkedIn ------------ I'd like to add you to my professional network on LinkedIn. - Alex Muscar Alex Muscar Student at Universitatea din Craiova Romania Confirm that you know Alex Muscar https://www.linkedin.com/e/-if48af-giwrckr2-4k/isd/2142627460/1VpMmRDn/ -- (c) 2010, LinkedIn Corporation

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[armedbear-devel] Proposed solution to the "too many functions in FASL" problem
by Alessio Stalla 13 Jan '11

13 Jan '11

Hello all, since my merge of the less-reflection branch with trunk[1], several of you have been bitten by the new limitation in the number of functions that can be contained in a FASL. The reflection-less scheme requires creating a loader class because it needs to spell out in the bytecode all the class names corresponding to compiled Lisp functions in the FASL. Functions are numbered from 1 onwards and a method is created that is a huge switch (actually a chain of if's) that returns the right function given its index: if(index >= 1 && index < 1024) { if(index == 1) return new function_1(); if(index == 2) return new function_2(); ... } else if(index >= 1024 ... In the presence of many functions, this method grows very large, eventually surpassing the JVM's 64k method size limit. A couple of days ago Erik and I discussed a bit about the issue and how to solve it. One option is to implement method splitting for the big FASL loader method. Method splitting in general is hard (you'd need some form of CPS conversion) but in this case it's quite easy. The current scheme, though, has drawbacks: it's more complicated than it used to be, and it's not that beneficial performance-wise - from a profiling I did a while ago, its performance gains amounted to ~1% of our loading time, which is completely dominated by I/O and UTF-8 decoding. So, there's another option: go back to reflection-based loading. Using reflection has the benefit of being simpler. On certain platforms (e.g. mobile JVMs or similar, like Dalvik), reflection has a higher cost, but we currently don't run satisfactorily on those platforms anyway and we'd require multiple changes to do so. After my discussion with Erik, a further refinement of this second option came to my mind. As part of the no-reflection effort, the compiler was changed to stop emitting calls to loadCompiledFunction(className) in favor of generating `new className()` bytecode for local functions, in accordance with the goal of avoiding reflection as much as possible. A special classloader is used to both resolve those local function references, and to load the FASL loader class (and thus transitively all top-level functions). I propose keeping the compilation of local function references as it is, and thus the special classloader; and use it directly (via reflection) to load top-level functions, instead of generating one big loader method. This would result in slightly less reflection, but more importantly in a clearer function loading scheme, and less development effort compared to returning completely to the reflection-based scheme also for local functions. What do you think? If it's not clear, both Erik and I sponsor the solution of returning to a reflection-based approach, but we'd like to hear everyone's opinions. Bye, Alessio

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[armedbear-devel] Recovering "special slots" after package deletion
by Erik Huelsmann 11 Jan '11

11 Jan '11

The other day, Ville and I were discussing the issue with recovery of "special slots" after package deletion on IRC. Let me start by describing the problem for you first. After that I'll describe the solution I see, however, your feedback on the solution is very much appreciated. Special symbol slots? ABCL - like SBCL and CCL - uses a thread-local array containing the 'current' values of its special variables. All symbols which have been declared or declaimed special at one point or another have been assigned an index in this array. This method allows very quick access to the special value (and hence the symbol value) with only a single level of added indirection: the symbols hold the number of their index in the array, meaning that having a reference to the symbol and the current thread is enough to find its value. When I implemented it, it was a huge difference with respect to the method we were using before. Do those need release? Since packages can be deleted, symbols be garbage collected. In the current implementation, GC-ing a special symbol will leave the slot it was assigned unused. There's no way the slot gets reassigned, because nothing keeps track of these 'dead' slots. To make matters worse: there may be huge lisp structures referenced in the dead slot, because it's also not cleared out. In the very long run, this will cause issues in scenarios as Blake describes where one creates, deletes and re-creates packages. The symbols in the packages are new symbols on every re-creation. Yet there are only 4096 spots in the special-symbols table. The solution? Well, the solution I see is to use the Object.finalize() method to release the index back to a freelist. There's a downside here though: the 4096 slots may run out before a multi-gb system sees its first GC run. There are two ways out here: grow the table once we run out of free slots (even though many potentially free slots may be pending GC). Or force a gc/runFinalization() run when running out of indices. Surely a combination of both would also be an option. Ville partially objects to the above because he's used to the pattern "you can't depend on finalize() to be invoked". Reading its documentation and googling the topic a bit, I see that finalize() can't be depended upon especially on JVM termination. However, that particular case isn't interesting here: we're looking at releasing "memory" related resources, which seems to be the exact purpose of finalize() as described in all the web docs I found. Can you comment? Is my approach as sane as I think it is? Bye, Erik.

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[armedbear-devel] Memory leak
by Blake McBride 10 Jan '11

10 Jan '11

Greetings, I think there is a memory leak. I constructed the enclosed lisp files and compiled memtest2.lisp. On a clean abcl evocation I load "try.lisp" and run the various tryN functions. I've mainly been using N=10. You can see that there is a leak when running memtest2. This leak would kill my app after ongoing usage. On another note, memtest2.lisp creates 1000 functions. If you change the number to 10,000 it can't be compiled. This speaks to the error that was reported recently. Thanks. Blake McBride

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[armedbear-devel] [CfP] European Lisp Symposium deadline extension
by Didier Verna 10 Jan '11

10 Jan '11

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 4th European Lisp Symposium Special Focus on Parallelism & Efficiency March 31 - April 1st, 2011 TUHH, Hamburg University of Technology Hamburg, Germany http://www.european-lisp-symposium.org/ Sponsored by EPITA, Lispworks, Franz Inc. and Nova Sparks ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Important Dates ~~~~~~~~~~~~~~~~ + Submission Deadline: January 16, 2011 --- EXTENDED + Author Notification: February 06, 2011 + Final Paper Due: February 28, 2011 + Symposium: March 31 - April 1st, 2011 Authors of accepted research contributions will be invited to submit an extended version of their papers for journal publication. Invited Speakers: ~~~~~~~~~~~~~~~~~ Marc Battyani (Nova Sparks) Craig Zilles (University of Illinois) Scope ~~~~~~ The purpose of the European Lisp Symposium is to provide a forum for the discussion and dissemination of all aspects of design, implementation and application of any of the Lisp dialects, including Common Lisp, Scheme, Emacs Lisp, AutoLisp, ISLISP, Dylan, Clojure, ACL2, ECMAScript, Racket, SKILL and so on. We encourage everyone interested in Lisp to participate. The European Lisp Symposium 2011 invites high quality papers about novel research results, insights and lessons learned from practical applications, and educational perspectives. We also encourage submissions about known ideas as long as they are presented in a new setting and/or in a highly elegant way. This year's focus will be directed towards "Parallelism & Efficiency". We especially invite submissions in the following areas: + Parallel and distributed computing + Code generation for multi-core architectures + Code generation for HTM + Large and ultra-large systems + Optimization techniques + Embedded applications Contributions are also welcome in other areas, including but not limited to: + Context-, aspect-, domain-oriented and generative programming + Macro-, reflective-, meta- and/or rule-based development approaches + Language design and implementation + Language integration, inter-operation and deployment + Development methodologies, support and environments + Educational approaches and perspectives + Experience reports and case studies Technical Program: ~~~~~~~~~~~~~~~~~~ We invite submissions in the following forms: * Papers: Technical papers of up to 15 pages that describe original results or explain known ideas in new and elegant ways. * Demonstrations: Abstracts of up to 4 pages for demonstrations of tools, libraries, and applications. * Tutorials: Abstracts of up to 4 pages for in-depth presentations about topics of special interest for at least 90 minutes and up to 180 minutes. * Lightning talks: Abstracts of up to one page for talks to last for no more than 5 minutes. All submissions should be formatted following the ACM SIGS guidelines and include ACM classification categories and terms. For more information on the submission guidelines and the ACM keywords, see: http://www.acm.org/sigs/publications/proceedings-templates http://www.acm.org/about/class/1998 Submissions should be uploaded to Easy Chair, at the following address: http://www.easychair.org/conferences/?conf=els2011 Programme Chair ~~~~~~~~~~~~~~~~ Didier Verna - EPITA Research and Development Laboratory, France Local Chair ~~~~~~~~~~~~ Ralf Moeller - Hamburg University of Technology, Germany Programme Committee ~~~~~~~~~~~~~~~~~~~~ Antonio Leitao - Instituto Superior Tecnico/INESC-ID, Portugal Christophe Rhodes - Goldsmiths College, University of London, UK David Edgar Liebke - Relevance Inc., USA Didier Verna - EPITA Research and Development Laboratory, France Henry Lieberman - MIT Media Laboratory, USA Jay McCarthy - Brigham Young University, USA Jose Luis Ruiz Reina - Universidad de Sevilla, Spain Marco Antoniotti - Universita Milano Bicocca, Italy Manuel Serrano - INRIA, France Michael Sperber - DeinProgramm, Germany Pascal Costanza - Vrije Universiteit of Brussel, Belgium Scott McKay - ITA Software, USA -- Resistance is futile. You will be jazzimilated. Scientific site: http://www.lrde.epita.fr/~didier Music (Jazz) site: http://www.didierverna.com

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[armedbear-devel] Broken link in documentation
by Didier Verna 06 Jan '11

06 Jan '11

The page http://common-lisp.net/project/armedbear/doc/abcl-user.html contains two pointers to files under this directory: http://trac.common-lisp.net/armedbear/browser/trunk/abcl/examples/abcl/java… both are broken links. In fact, it seems that every example pointer to trac is broken. Once in the trac "not found" page, I have a 50% chance to get an Internal Server Error when clinking on Search, but last time, I got to a working page showing this last change: (delete) @12718 [12719] 8 months mevenson Example reorganzation: delete 'abcl' directory. It seems to indicate that the abcl directory under examples/ should be removed in the links, which indeed seems to be the case: I can reach this one instead: http://trac.common-lisp.net/armedbear/browser/trunk/abcl/examples -- Resistance is futile. You will be jazzimilated. Scientific site: http://www.lrde.epita.fr/~didier Music (Jazz) site: http://www.didierverna.com

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[armedbear-devel] JSR-223: path names with spaces and output capturing
by Martin Hepperle 05 Jan '11

05 Jan '11

Hello all, hope you had good start into 2011. ABCL via JSR-223 is almost perfect now, but I have two things which do not work perfectly: A) How to handle path names with spaces? When my Java application is installed in a path with spaces (which should be no problem nowadays in 2011), I receive the following error when the ABCL engine is created: ERROR placeholder called with arguments: #<ERROR {590510}> "Failed to find loadable system file in boot classpath 'jar:file:/D:/Programme/MH%20AeroTools/PROPPY/bin/languages/abcl.jar!/org/armedbear/lisp/boot.lisp'" The spaces have been encoded by "%20", but obviously ABCL does not understand this boot path. B) How to redirect I/O of the script engine? If I want to use a scripting engine in my application, the user may make mistakes. OK. For this purpose I have to 1) catch errors in Java, which works by placing the following two lines into "abcl-script-config.lisp" (in-package :abcl-script) (setq *use-throwing-debugger* nil) 2) catch standard error and standatd output. While JSR provides an interface for this vi "setWriter" and "setErrorWriter", I discovered that most JSR-223 engines do not implement this correctly. So I resorted to redirect the system streams via "System.setOut" and "System.setErr", which worked for all JSR-223 implementations so far ... except ABCL. I always reveive error mesages, as well as the initialization message (...ABCL: configured ) on standard output, possibly bypassing the system streams? So how can I capture errors? Is t possible to rediredt errro and output (e.g.of print) to the standard output and standard error streams of the Java system? Maybe there is some extra initialization needed in ABCL to do this in case of the JSR-223 engine. Thanks for listening, Martin

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[armedbear-devel] Several ABCL/Java questions
by Didier Verna 04 Jan '11

04 Jan '11

Hello, I'm trying to port Clon[1] to ABCL, or at least figure out whether it makes sense at all. My Java programming experience boils down to a Hello World program 10 years ago or so, so some questions belong to the Java side of ABCL for sure :-). I would be grateful if somebody can help me answer these. 1/ Is it possible to create standalone ABCL executables and how ? 2/ ABCL doesn't seem to provide a [set|put]env function. From what I can gather from the internet, that would be because there's no such thing in Java. I've seen some nasty tricks around consisting in modifying the (application-local) initial memory mapping of the environment, but that's all. Is this correct ? 3/ It seems that ABCL does not have a complete MOP. In particular, I couldn't find a validate-superclass function. Is this correct ? Does this mean that classes/superclasses are implicitely "validated" ? 4/ There is a place where I need to access low-level information about a stream in order to figure out whether it's connected to a tty, and in that case, what's the tty line-width. In other implementations, I have native support (or cffi support in the case of CLISP) for calling ioctl with the TIOCGWINSZ argument. It either gets me the tty line width or throws me an ENOTTY error in the face which is fine. How can I do something similar in ABCL ? Thank you very much ! Footnotes: [1] http://www.lrde.epita.fr/~didier/software/lisp/clon.php -- Resistance is futile. You will be jazzimilated. Scientific site: http://www.lrde.epita.fr/~didier Music (Jazz) site: http://www.didierverna.com

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armedbear-devel January 2011