Re: [Haifux] Multi-thread debugging for C++ on Linux
-- Zaar On Fri, Nov 28, 2008 at 5:12 PM, Ohad Lutzky [EMAIL PROTECTED] wrote: Hello all, I am examining the issue of debugging multi-threaded (specifically using pthreads, and written in C or C++) applications in Linux. The basic tools, as far as I can tell, are somewhat lacking; while the DDD documentation does have a screenshot showing a suspend button in Status-Threads, this does not show up in my version of ddd (3.3.11), and I can't really figure out how to do this from within gdb. Is it even possible? As far as I know, this is possible with Java, and I'm guessing that it has to do with additional JRE instrumentation (the debugger tells JRE to suspend the thread, and while the Linux thread is running, the JRE code therein does a sched_yield). Not answering your questions, but try insight debugger. Its the only debugger that worked for me with complicated C++ templates. So my question are: 1. Am I missing something, and this is in fact possible with GDB? If so, is there a graphical interface (my coworkers are fond of those...) which supports this? 2. Is there a different Linux (on x86) debugger which does support this? 3. What is the situation of this problem on other OSes? 4. What other neat thread-related debugging tools (other than suspending individual threads, that is) are there, and which debuggers support them? I've been trying to google the answers to these questions, but so far I've come up short. Any wise keywords would be appreciated :) -- Man is the only animal that laughs and weeps, for he is the only animal that is struck with the difference between what things are and what they ought to be. - William Hazlitt Ohad Lutzky ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Multi-thread debugging for C++ on Linux
May I recommend using emacs as the front-end for gdb. -- yotam On Fri, 28 Nov 2008 17 Ohad Lutzky [EMAIL PROTECTED] wrote ... So my question are 1. Am I missing something, and this is in fact possible with GDB? If so, is there a graphical interface (my coworkers are fond of those...) which supports this? 2. ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
[Haifux] Why open source
Hi, Lets say you wrote a utility that may be useful to others. Why would you open source it? How can you earn money from opening the code and giving it for free? Source forge is making money from hosting your utility, Wikipedia is making money from documenting it, what is left for the developer? Is there someone who can give a lecture on the subject? Are there more people interested in the subject? Thanks, Tal. ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Multi-thread debugging for C++ on Linux
Hi This is an interesting issue you have raised here. Indeed, in JVM it seems to be more easy to breakpoint a thread, but actually there is nothing too special that Java does that other native debugger can't do. One type of breakpoints is called software breakpoints and are based on int3 Intel instruction (special type of software trap/exception, like int0x80 sys call). It should be inserted at the code level. So as long as the threads are kernel threads and have different pids (which is what happens in latest fixed versions of POSIX Linux threads), it should be possible to breakpoint each thread separately. There is also something called hardware breakpoints: http://www.codeproject.com/KB/debug/hardwarebreakpoint.aspx They are used to data breakpoints - when ever some data address changes, it breakpoints the program. But never mind about them. As for the gdb and DDD, check these out: http://www.gnu.org/manual/ddd/html_mono/ddd.html#Threads http://www.gnu.org/manual/ddd/html_mono/ddd.html#Threads http://sources.redhat.com/gdb/current/onlinedocs/gdb_6.html#SEC49 I would also add that being able to stop a specific thread may indeed be useful, but you should not rely on such a kind of debugging to ensure correctness of your multithreaded program. You should do a much more thorough different-concurrent-scenarios debugging and than printfing and asserts might be more useful. Gabi _ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ohad Lutzky Sent: Friday, November 28, 2008 5:12 PM To: Haifux Cc: Yigal Korman Subject: [Haifux] Multi-thread debugging for C++ on Linux Hello all, I am examining the issue of debugging multi-threaded (specifically using pthreads, and written in C or C++) applications in Linux. The basic tools, as far as I can tell, are somewhat lacking; while the DDD documentation does have a screenshot showing a suspend button in Status-Threads, this does not show up in my version of ddd (3.3.11), and I can't really figure out how to do this from within gdb. Is it even possible? As far as I know, this is possible with Java, and I'm guessing that it has to do with additional JRE instrumentation (the debugger tells JRE to suspend the thread, and while the Linux thread is running, the JRE code therein does a sched_yield). So my question are: 1. Am I missing something, and this is in fact possible with GDB? If so, is there a graphical interface (my coworkers are fond of those...) which supports this? 2. Is there a different Linux (on x86) debugger which does support this? 3. What is the situation of this problem on other OSes? 4. What other neat thread-related debugging tools (other than suspending individual threads, that is) are there, and which debuggers support them? I've been trying to google the answers to these questions, but so far I've come up short. Any wise keywords would be appreciated :) -- Man is the only animal that laughs and weeps, for he is the only animal that is struck with the difference between what things are and what they ought to be. - William Hazlitt Ohad Lutzky ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Why open source
2008/11/28 Tal Abir [EMAIL PROTECTED]: Hi, Lets say you wrote a utility that may be useful to others. Why would you open source it? How can you earn money from opening the code and giving it for free? Source forge is making money from hosting your utility, Wikipedia is making money from documenting it, what is left for the developer? Some men aren't looking for anything logical, like money. They can't be bought, bullied, reasoned or negotiated with. Some men just want to watch the world burn. Is there someone who can give a lecture on the subject? Are there more people interested in the subject? Ask Alfred. -- Dotan Cohen http://what-is-what.com http://gibberish.co.il א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת ا-ب-ت-ث-ج-ح-خ-د-ذ-ر-ز-س-ش-ص-ض-ط-ظ-ع-غ-ف-ق-ك-ل-م-ن-ه-و-ي А-Б-В-Г-Д-Е-Ё-Ж-З-И-Й-К-Л-М-Н-О-П-Р-С-Т-У-Ф-Х-Ц-Ч-Ш-Щ-Ъ-Ы-Ь-Э-Ю-Я а-б-в-г-д-е-ё-ж-з-и-й-к-л-м-н-о-п-р-с-т-у-ф-х-ц-ч-ш-щ-ъ-ы-ь-э-ю-я ä-ö-ü-ß-Ä-Ö-Ü ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Why open source
I think the question is why not open source? The question is not how you make money from open source, although this is not always obvious, you can see many companies who does make money from open source. But how do you make money from closed source? this remains a mystery to me. I would be happy to give a talk about it, actually I think it is better to have a discussion about it so it will not be a talk but rather a discussion. -- Ori Idan On Fri, Nov 28, 2008 at 6:07 PM, Tal Abir [EMAIL PROTECTED] wrote: Hi, Lets say you wrote a utility that may be useful to others. Why would you open source it? How can you earn money from opening the code and giving it for free? Source forge is making money from hosting your utility, Wikipedia is making money from documenting it, what is left for the developer? Is there someone who can give a lecture on the subject? Are there more people interested in the subject? Thanks, Tal. ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Multi-thread debugging for C++ on Linux
i did not understand what feature you want. gdb supports suspending all the threads together (which is what you normally want), continuing all of them together, and doing a single-step in one thread (which has the annoying side-effect of allowing other threads to also continue executing at the same time - this is the one feature of gdb which i find annoying). generally, i don't debug multi-threaded programs using a debugger. i use logs, a single log file, where each line contains the thread-id (so you'll be able to filter out messages belonging to a single thread of execution). i use the debugger for two major activities: 1. debugging a crashed process (i.e. analysis of a code file) - gdb supports this and shows you the stacks and variables of all the threads. 2. break-pointing a program at a given command (or when a given memory address is being altered or accessed) - and studing the state of the program without single-stepping. if you find the solution to single-stepping a single thread - let me know. this will be a nice feature. i once thought i saw a way to do it, but when i searched for this again - i didn't find it. --guy Ohad Lutzky wrote: Hello all, I am examining the issue of debugging multi-threaded (specifically using pthreads, and written in C or C++) applications in Linux. The basic tools, as far as I can tell, are somewhat lacking; while the DDD documentation does have a screenshot showing a suspend button in Status-Threads, this does not show up in my version of ddd (3.3.11), and I can't really figure out how to do this from within gdb. Is it even possible? As far as I know, this is possible with Java, and I'm guessing that it has to do with additional JRE instrumentation (the debugger tells JRE to suspend the thread, and while the Linux thread is running, the JRE code therein does a sched_yield). So my question are: 1. Am I missing something, and this is in fact possible with GDB? If so, is there a graphical interface (my coworkers are fond of those...) which supports this? 2. Is there a different Linux (on x86) debugger which does support this? 3. What is the situation of this problem on other OSes? 4. What other neat thread-related debugging tools (other than suspending individual threads, that is) are there, and which debuggers support them? I've been trying to google the answers to these questions, but so far I've come up short. Any wise keywords would be appreciated :) -- Man is the only animal that laughs and weeps, for he is the only animal that is struck with the difference between what things are and what they ought to be. - William Hazlitt Ohad Lutzky ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Why open source
I would be happy to participate in such discussion but would you open a full scale company for earning money from a little utility. I don't think it will hold. People today earn money just from writing blogs (though publishing a piece of code and then earn money from blogging about it sounds like as a start of an idea) The other option (at least as I see it) is not closed source but rather not to publish it at all. Thus everyone will continue writing the same utilities and keep it for themselves. Tal. On Fri, Nov 28, 2008 at 6:38 PM, Ori Idan [EMAIL PROTECTED] wrote: I think the question is why not open source? The question is not how you make money from open source, although this is not always obvious, you can see many companies who does make money from open source. But how do you make money from closed source? this remains a mystery to me. I would be happy to give a talk about it, actually I think it is better to have a discussion about it so it will not be a talk but rather a discussion. -- Ori Idan On Fri, Nov 28, 2008 at 6:07 PM, Tal Abir [EMAIL PROTECTED] wrote: Hi, Lets say you wrote a utility that may be useful to others. Why would you open source it? How can you earn money from opening the code and giving it for free? Source forge is making money from hosting your utility, Wikipedia is making money from documenting it, what is left for the developer? Is there someone who can give a lecture on the subject? Are there more people interested in the subject? Thanks, Tal. ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Multi-thread debugging for C++ on Linux
A minor technical note: On Fri, Nov 28, 2008 at 06:17:38PM +0200, gabik wrote: So as long as the threads are kernel threads and have different pids (which is what happens in latest fixed versions of POSIX Linux threads) Threads had different PIDs even before that. They were actually even less connected before the NPTL change in Linux 2.6 . But then again, most of us don't need to care about Linux 2.4 and older... -- Tzafrir Cohen | [EMAIL PROTECTED] | VIM is http://tzafrir.org.il || a Mutt's [EMAIL PROTECTED] || best ICQ# 16849754 || friend ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Why open source
On Fri, Nov 28, 2008 at 06:07:09PM +0200, Tal Abir wrote: Hi, Lets say you wrote a utility that may be useful to others. Is it useful for you as well? Why would you open source it? There are several reasons. Do you think you can actually make money from selling the software as a stand-alone product? Without support? If you make it free software you can still sell support. You're more likely to get good bug reports and even some patches. Furthermore, if you actually need that software to work well for you (e.g. to offer a better service to your clients) then making it free software reduces the development cost. It also reduces the deployment cost, because there's no licensing overhead and there's no inherent conflict between the developer and the user. For instance, it means people can get support from someone else, and hence they won't be left with a useless pile of bits if you're gone. It gives the software a higher value. How can you earn money from opening the code and giving it for free? There are several possible methods. Here is an article discussing several of them: http://www.letmegooglethatforyou.com/?q=how+can+I+make+money+from+opensource That said, it is still a tricky business. But then again, getting people to pay you for limited usage licenses for a software isn't that easy as well (specifically if there is an interesting competition). Note that I did not write here that you should release your software as free software. You wrote it, and it is up to you to license it. Source forge is making money from hosting your utility, SourceForge makes osme money form adds. But also from selling the proprietary SourceForge development platform. Wikipedia is making money from documenting it, Wikimedia is hosted by the Wikimedia foundation, which is a NGO. The content of Wikipedia is available under the terms of the GFDL. It is run by a software called wikimedia which is free software as well. Wikipedia carries no adds. You'll occasionally see there a call for donations. what is left for the developer? Is there someone who can give a lecture on the subject? Are there more people interested in the subject? -- Tzafrir Cohen | [EMAIL PROTECTED] | VIM is http://tzafrir.org.il || a Mutt's [EMAIL PROTECTED] || best ICQ# 16849754 || friend ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
Re: [Haifux] Multi-thread debugging for C++ on Linux
-- Zaar On Fri, Nov 28, 2008 at 8:29 PM, Ohad Lutzky [EMAIL PROTECTED] wrote: Hello all, Allow me to add a certain point which wasn't clear in my question: This is NOT for me. Myself, I use vim and gdb, and rarely ever write software with more than one thread (per process, that is ;) ). This is intended for other users, which are not necessarily highly familiar with Linux programming, and the ideal solution for my problem would be an all-in-one GUI debugger (such as DDD). I am, however, open to any neat tricks you might have in mind, which are not in silver-platter-GUI form. Hai: Thanks, I'll take a look at Insight. (Doesn't seem as nice as ddd though, not even a builtin gdb console... what features should I look at?) Yes, its GUI looks eagy. It does have a gdb console (View-Console - its not a shell console but gdb console). Insight did a best job for me debugging project that heavily used C++ templating, where ddd got lost tracking source code. Yotam: We're a VIM shop ;) (and still, would this be beneficial? I'm pretty sure that it's a rather thin frontend) Gabi: Debugging is rarely intended to verify code correctness, nay? :) But gdb is indeed capable of those features, they just seemed pretty basic to me. Guy: The solution to the single-stepping problem would essentially be suspend all threads but this one, which indeed gdb can't seem to do. I'm not sure why. At any rate, thanks for the input, guys. I guess the answer I got is that gdb is still the best thread-debugging solution in Linux. On Fri, Nov 28, 2008 at 6:40 PM, guy keren [EMAIL PROTECTED] wrote: i did not understand what feature you want. gdb supports suspending all the threads together (which is what you normally want), continuing all of them together, and doing a single-step in one thread (which has the annoying side-effect of allowing other threads to also continue executing at the same time - this is the one feature of gdb which i find annoying). generally, i don't debug multi-threaded programs using a debugger. i use logs, a single log file, where each line contains the thread-id (so you'll be able to filter out messages belonging to a single thread of execution). i use the debugger for two major activities: 1. debugging a crashed process (i.e. analysis of a code file) - gdb supports this and shows you the stacks and variables of all the threads. 2. break-pointing a program at a given command (or when a given memory address is being altered or accessed) - and studing the state of the program without single-stepping. if you find the solution to single-stepping a single thread - let me know. this will be a nice feature. i once thought i saw a way to do it, but when i searched for this again - i didn't find it. --guy Ohad Lutzky wrote: Hello all, I am examining the issue of debugging multi-threaded (specifically using pthreads, and written in C or C++) applications in Linux. The basic tools, as far as I can tell, are somewhat lacking; while the DDD documentation does have a screenshot showing a suspend button in Status-Threads, this does not show up in my version of ddd (3.3.11), and I can't really figure out how to do this from within gdb. Is it even possible? As far as I know, this is possible with Java, and I'm guessing that it has to do with additional JRE instrumentation (the debugger tells JRE to suspend the thread, and while the Linux thread is running, the JRE code therein does a sched_yield). So my question are: 1. Am I missing something, and this is in fact possible with GDB? If so, is there a graphical interface (my coworkers are fond of those...) which supports this? 2. Is there a different Linux (on x86) debugger which does support this? 3. What is the situation of this problem on other OSes? 4. What other neat thread-related debugging tools (other than suspending individual threads, that is) are there, and which debuggers support them? I've been trying to google the answers to these questions, but so far I've come up short. Any wise keywords would be appreciated :) -- Man is the only animal that laughs and weeps, for he is the only animal that is struck with the difference between what things are and what they ought to be. - William Hazlitt Ohad Lutzky ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux -- Man is the only animal that laughs and weeps, for he is the only animal that is struck with the difference between what things are and what they ought to be. - William Hazlitt Ohad Lutzky ___ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux ___ Haifux mailing list Haifux@haifux.org
