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  • Need Firefox plug-in to show POSTed variables

    - by Cyrcle
    I need to find out what variables and values are being POSTed to a script that I'm debugging. It's doing something strange to them, and it needs to start a session so I can't ouput them right at the beginning. I'm hoping to find a plug-in for Firefox that will show me what they are directly from the browser. Does anyone know of such a thing?

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  • linux, LD_PRELOAD error

    - by user286215
    Hello, i am new in programming under linux and trying to get working this code: http://scaryreasoner.wordpress.com/2007/11/17/using-ld_preload-libraries-and-glibc-backtrace-function-for-debugging/ but getting error: "ERROR: ld.so: object 'libwrap_ioctl.so' from LD_PRELOAD cannot be preloaded: ignored." what can cause it? system - Archlinux, kernel 2.6.32 thank you for answers upd1: "Check with ldd libwrap_ioctl.so if some dependency of this library is missing." checked. no, i have all needed libraries

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  • How early can I call kalloc in an arm linux kernel?

    - by Isaac Sutherland
    I would like to dynamically allocate memory from the machine_init function in my arm linux kernel. Calling kalloc can result in a complete failure of the system to boot. My debugging tools are very limited so I can't give much more information regarding the failure. Simply put, is it legal to call kalloc from a machine_init function in arm linux, and, if not, is there an alternative?

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  • VS 2010 IDE 2GB limt

    - by user561732
    I am using VS 2010 on a win 7 64 bit system with 8 GB of memory. My application is 32 bit. While in the VS 2010 .Net IDE, the app shows up in the Windows task manager as "MyApp.vshost.exe *32" while the VS IDE itself shows up as "devenv.exe *32". I checked and it appears that the VS 2010 IDE file (devenv.exe) is complied with the /LargeAddressAware flag. However, when debugging large models, the IDE fails with an Out of memory exception. In the Windows Task manager, the "MyApp.vshost.exe *32" process indicates about 1400 MB of memory usage (while the "devenv.exe *32" process is well under 500 MB). Is it possible to set the "MyApp.vshost.exe *32" process to be /LargeAddressAware in order to avoid this out of memory situation? If so, how can this be done in the IDE. While setting the final application binary to be /LargeAddressAware would work, I still need to be able to debug the app in the IDE with these type of large models. I should also note that my app has a deep object hierarchy with many collections that together required a lot of memory. However, my issue is not related to trying to create say 1 large array that requires greater then 2 GB of memory etc. I should note that I am able to run the same app in the VB6 IDE and not get an out of memory situation as long as the VB6 IDE is made /LargeAddressAware. In the case of VB6, the IDE and the app being debugged are part of the same process (and not split into 2 as is the case with VS 2010.) The VB6 process can be larger then 3 GB without running into out of memory issues. Ultimately, my objective is to have my app run completely in 64 bit to access more memory. I am hoping that in such cases, the IDE will allow the debugging process to exceed 2 GB without crashing (and certainly more then 1.4 GB as is the current case). However, for now, while 95% of my app is 64 bit, I am calling a legacy COM 32 bit DLL and as such, my entire app is forced to still run in 32 bit mode until I replace that DLL.

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  • c++ program debugged well with Cygwin4 (under Netbeans 7.2) but not with MinGW (under QT 4.8.1)

    - by GoldenAxe
    I have a c++ program which take a map text file and output it to a graph data structure I have made, I am using QT as I needed cross-platform program and GUI as well as visual representation of the map. I have several maps in different sizes (8x8 to 4096x4096). I am using unordered_map with a vector as key and vertex as value, I'm sending hash(1) and equal functions which I wrote to the unordered_map in creation. Under QT I am debugging my program with QT 4.8.1 for desktop MinGW (QT SDK), the program works and debug well until I try the largest map of 4096x4096, then the program stuck with the following error: "the inferior stopped because it received a signal from operating system", when debugging, the program halt at the hash function which used inside the unordered_map and not as part of the insertion state, but at a getter(2). Under Netbeans IDE 7.2 and Cygwin4 all works fine (debug and run). some code info: typedef std::vector<double> coordinate; typedef std::unordered_map<coordinate const*, Vertex<Element>*, container_hash, container_equal> vertexsContainer; vertexsContainer *m_vertexes (1) hash function: struct container_hash { size_t operator()(coordinate const *cord) const { size_t sum = 0; std::ostringstream ss; for ( auto it = cord->begin() ; it != cord->end() ; ++it ) { ss << *it; } sum = std::hash<std::string>()(ss.str()); return sum; } }; (2) the getter: template <class Element> Vertex<Element> *Graph<Element>::getVertex(const coordinate &cord) { try { Vertex<Element> *v = m_vertexes->at(&cord); return v; } catch (std::exception& e) { return NULL; } } I was thinking maybe it was some memory issue at the beginning, so before I was thinking of trying Netbeans I checked it with QT on my friend pc with a 16GB RAM and got the same error. Thanks.

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  • Javascript Debuuger plugin for eclipse

    - by vineth
    hi , I am new for java and iam doing the project with extjs & JAVA ,i using eclipse version (Eclipse Java EE IDE for Web Developers. Build id: 20100218-1602) . Can any one suggest any javascript debugging plugin for this id or pls provide link.. Thanks in advance

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  • HTTP 403.9 - Access Forbidden: Too many users are connected

    - by sdsd
    hi I have created an application in VStudio. It ran nicely in debugging mode, but my computer became slower and slower as I worked until it finaly became frozen. after I manualy restarted it, the app wasn't running any more in debug and I get this execption in the browser. Only I am connected right now to the app. I have restarted the computer so there coudn't be any instance of a client connected I have removed and reinstalled the IIS what is wrong?

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  • Netbeans platform tutorials

    - by James P.
    I mostly use Eclipse but have mentionned Netbeans on my cv. Are there any good concise and up-to-date tutorials apart from the official ones that could bring me up to speed on how to use the platform efficiently (shortcuts, debugging, views ...)? This excludes programming tutorials as I don't really need them unless there's a special manipulation involved.

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  • Netbeans IDE tutorials

    - by James P.
    I mostly use Eclipse but have mentionned Netbeans on my cv. Are there any good concise and up-to-date tutorials apart from the official ones that could bring me up to speed on how to use the IDE efficiently (shortcuts, debugging, views ...)? This excludes programming tutorials as I don't really need them unless there's a special manipulation involved.

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  • SQL Server using SSH-tunnel from Visual Studio

    - by pbt
    Hi, I recently contacted a web host regarding support for external database access to a Microsoft SQL Server database included in a package they offer. They replied saying that it is only possible with an SSH-tunnel. Is it possible to connect to a SQL Server database in Visual Studio using an SSH-tunnel? It is important for me to be able to access the database from my local machine (for debugging, generating LINQ classes, editing tables, etc). Or, how should I go about working with their database?

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  • readonly property setter

    - by Anonymous Coward
    Hi Everyone After a extensive debugging session I found that the problem was that I called the setter of a readonly property. Is there a trick to provoke a compiler warning when this happens? Because marking the setter private does not work. Cheers, CA

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  • How to prevent SQL Compact DB to be erased?

    - by Skuta
    Hi, I'm developing an applciation using SQL Compact database in Visual Studio 2008. When I start the application and run the process, the data is being loaded into database for few hours worth of few tens of megabytes. However, when I quite debugging, change something in code (not in DB structure), run the project again, the database is erased. Does anyone know how to prevent this behavior? I need the data to stay in DB to test on it.

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  • Why is this condition never satisfied ?

    - by Patrick
    I don't know why this condition is never satisfied: I'm comparing two ArrayList values, and it is always false. if ( (Integer) results.get(rank) == (Integer) experts.get(j)) I'm debugging and I have exactly the same 2 values: 3043 and 3043 However it doesn't work. thanks

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  • I cannot change the target .NET Framework in IIS 6

    - by David Pike
    The option to target another version of the .Net Framework is disabled on a particular test system we are using on a current project. I have tried the following without success: Killing all W3WP.EXE processesRestarting the IIS serviceRemote Debugging has been removed from the box. Just hoping for some pointers.

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  • Why does Cacti keep waiting for dead poller processes?

    - by Oliver Salzburg
    sorry for the length I am currently setting up a new Debian (6.0.5) server. I put Cacti (0.8.7g) on it yesterday and have been battling with it ever since. Initial issue The initial issue I was observing, was that my graphs weren't updating. So I checked my cacti.log and found this concerning message: POLLER: Poller[0] Maximum runtime of 298 seconds exceeded. Exiting. That can't be good, right? So I went checking and started poller.php myself (via sudo -u www-data php poller.php --force). It will pump out a lot of message (which all look like what I would expect) and then hang for a minute. After that 1 minute, it will loop the following message: Waiting on 1 of 1 pollers. This goes on for 4 more minutes until the process is forcefully ended for running longer than 300s. So far so good I went on for a good hour trying to determine what poller might still be running, until I got to the conclusion that there simply is no running poller. Debugging I checked poller.php to see how that warning is issued and why. On line 368, Cacti will retrieve the number of finished processes from the database and use that value to calculate how many processes are still running. So, let's see that value! I added the following debug code into poller.php: print "Finished: " . $finished_processes . " - Started: " . $started_processes . "\n"; Result This will print the following within seconds of starting poller.php: Finished: 0 - Started: 1 Waiting on 1 of 1 pollers. Finished: 1 - Started: 1 So the values are being read and are valid. Until we get to the part where it keeps looping: Finished: - Started: 1 Waiting on 1 of 1 pollers. Suddenly, the value is gone. Why? Putting var_dump() in there confirms the issue: NULL Finished: - Started: 1 Waiting on 1 of 1 pollers. The return value is NULL. How can that be when querying SELECT COUNT()...? (SELECT COUNT() should always return one result row, shouldn't it?) More debugging So I went into lib\database.php and had a look at that db_fetch_cell(). A bit of testing confirmed, that the result set is actually empty. So I added my own database query code in there to see what that would do: $finished_processes = db_fetch_cell("SELECT count(*) FROM poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00'"); print "Finished: " . $finished_processes . " - Started: " . $started_processes . "\n"; $mysqli = new mysqli("localhost","cacti","cacti","cacti"); $result = $mysqli->query("SELECT COUNT(*) FROM poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00';"); $row = $result->fetch_assoc(); var_dump( $row ); This will output Finished: - Started: 1 array(1) { ["COUNT(*)"]=> string(1) "2" } Waiting on 1 of 1 pollers. So, the data is there and can be accessed without any problems, just not with the method Cacti is using? Double-check that! I enabled MySQL logging to make sure I'm not imagining things. Sure enough, when the error message is looped, the cacti.log reads as if it was querying like mad: 06/29/2012 08:44:00 PM - CMDPHP: Poller[0] DEVEL: SQL Cell: "SELECT count(*) FROM cacti.poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00'" 06/29/2012 08:44:01 PM - CMDPHP: Poller[0] DEVEL: SQL Cell: "SELECT count(*) FROM cacti.poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00'" 06/29/2012 08:44:02 PM - CMDPHP: Poller[0] DEVEL: SQL Cell: "SELECT count(*) FROM cacti.poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00'" But none of these queries are logged my MySQL. Yet, when I add my own database query code, it shows up just fine. What the heck is going on here?

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  • IP Micro-outages, telephone micro-outages, and CATV micro-outages

    - by Michael Graff
    This is a long and complicated question, mostly because it has been going on for 2.5 years without a solution in sight. It also is only one-third computer related, the other two-thirds are cable TV and cable-phone related. Background I have COX Communications for a cable provider, and we get Internet, digital cable TV, and digital phone service through them. The Internet is a SB5101 right now, and has been a DPC2100 and SB5120 in the past. Same results. The phone service is provided through a telephone interface mounted on the outside of the house (not classic VoIP) and the CATV is through a Scientific Atlanta receiver without DVR. I do have a TiVo connected to the CATV box. Symptoms The CATV shows "blocking" -- sometimes very very short duration where a few blocks appear on the screen. Sometimes it lasts long enough that the video "pauses" for 2-5 seconds, and rarely but not unseen the audio also fails. The CATV decoder box shows no correctable (FEC) or uncorrectable errors. That is, all BER counters are zero for the video stream. The Internet shows "micro-outages" where it appears that sent packets are not making it out, but I continue to receive packets from local modems. That is, pings stop coming back, but I continue to see modems broadcast for DHCP, and sometimes they ask more than once. The cable modem shows no errors during this time, but cable modems lie like you would not believe. It is actually possible to unplug the coax from the modem for 20 seconds and it reports NO ERRORS to the provider's tools. The phone service cuts out for 1-3 seconds, infrequently. When this happens, I hear NOTHING (not even comfort noise) and the remote side hears a "click" as if I were getting a call waiting message. However, there is no call incoming, other than the one I'm currently on of course. Things SEEM to happen more frequently when the temperature outside swings from cold to warm, so fall/spring seems worse than summer/winter. All micro-outages occur between once or twice a day (which I could ignore) to 10 times per hour. All SNR, signal levels, noise levels, etc. show very close to optimal when measured. COX's diagnosis This is a continual pain for me. Over the last 2.5 years, they have opened, "fixed" something, and closed the tickets. They close it without confirming that it is indeed better, and when I reopen they cannot do that, but instead they open a new ticket and send yet another low-level tech out to do the same signal tests and report that all is OK. I've finally gotten a line tech who has a clue and is motivated enough to pursue this with me. We have tried things like switching the local nodes over to UPS and generator power, but this does not trigger the noise. We have tried replacing all cabling, the tap outside my house, the modem, the CATV decoder -- all without resolution. Recently they have decided it is both my computer or switch, my TiVo, and my phone that are all broken and causing this issue. My debugging steps I spent the worse day of my TV-watching life yesterday and part of today. I watched live TV without the TiVo. I witnessed blocking, but it did "feel different." and was actually more severe. Some days it is better, some days it is worse, so perhaps this was just a very bad day. Today, I connected the TiVo to my DVD player, and ran two very long movies through it. I saw no blocking at all during nearly 6 hours of video. Suggestions? Does anyone have any suggestions on what to do next? I understand perhaps only the IP side can be addressed here, but it is one of the more limiting debugging options.

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  • Red Gate Coder interviews: Alex Davies

    - by Michael Williamson
    Alex Davies has been a software engineer at Red Gate since graduating from university, and is currently busy working on .NET Demon. We talked about tackling parallel programming with his actors framework, a scientific approach to debugging, and how JavaScript is going to affect the programming languages we use in years to come. So, if we start at the start, how did you get started in programming? When I was seven or eight, I was given a BBC Micro for Christmas. I had asked for a Game Boy, but my dad thought it would be better to give me a proper computer. For a year or so, I only played games on it, but then I found the user guide for writing programs in it. I gradually started doing more stuff on it and found it fun. I liked creating. As I went into senior school I continued to write stuff on there, trying to write games that weren’t very good. I got a real computer when I was fourteen and found ways to write BASIC on it. Visual Basic to start with, and then something more interesting than that. How did you learn to program? Was there someone helping you out? Absolutely not! I learnt out of a book, or by experimenting. I remember the first time I found a loop, I was like “Oh my God! I don’t have to write out the same line over and over and over again any more. It’s amazing!” When did you think this might be something that you actually wanted to do as a career? For a long time, I thought it wasn’t something that you would do as a career, because it was too much fun to be a career. I thought I’d do chemistry at university and some kind of career based on chemical engineering. And then I went to a careers fair at school when I was seventeen or eighteen, and it just didn’t interest me whatsoever. I thought “I could be a programmer, and there’s loads of money there, and I’m good at it, and it’s fun”, but also that I shouldn’t spoil my hobby. Now I don’t really program in my spare time any more, which is a bit of a shame, but I program all the rest of the time, so I can live with it. Do you think you learnt much about programming at university? Yes, definitely! I went into university knowing how to make computers do anything I wanted them to do. However, I didn’t have the language to talk about algorithms, so the algorithms course in my first year was massively important. Learning other language paradigms like functional programming was really good for breadth of understanding. Functional programming influences normal programming through design rather than actually using it all the time. I draw inspiration from it to write imperative programs which I think is actually becoming really fashionable now, but I’ve been doing it for ages. I did it first! There were also some courses on really odd programming languages, a bit of Prolog, a little bit of C. Having a little bit of each of those is something that I would have never done on my own, so it was important. And then there are knowledge-based courses which are about not programming itself but things that have been programmed like TCP. Those are really important for examples for how to approach things. Did you do any internships while you were at university? Yeah, I spent both of my summers at the same company. I thought I could code well before I went there. Looking back at the crap that I produced, it was only surpassed in its crappiness by all of the other code already in that company. I’m so much better at writing nice code now than I used to be back then. Was there just not a culture of looking after your code? There was, they just didn’t hire people for their abilities in that area. They hired people for raw IQ. The first indicator of it going wrong was that they didn’t have any computer scientists, which is a bit odd in a programming company. But even beyond that they didn’t have people who learnt architecture from anyone else. Most of them had started straight out of university, so never really had experience or mentors to learn from. There wasn’t the experience to draw from to teach each other. In the second half of my second internship, I was being given tasks like looking at new technologies and teaching people stuff. Interns shouldn’t be teaching people how to do their jobs! All interns are going to have little nuggets of things that you don’t know about, but they shouldn’t consistently be the ones who know the most. It’s not a good environment to learn. I was going to ask how you found working with people who were more experienced than you… When I reached Red Gate, I found some people who were more experienced programmers than me, and that was difficult. I’ve been coding since I was tiny. At university there were people who were cleverer than me, but there weren’t very many who were more experienced programmers than me. During my internship, I didn’t find anyone who I classed as being a noticeably more experienced programmer than me. So, it was a shock to the system to have valid criticisms rather than just formatting criticisms. However, Red Gate’s not so big on the actual code review, at least it wasn’t when I started. We did an entire product release and then somebody looked over all of the UI of that product which I’d written and say what they didn’t like. By that point, it was way too late and I’d disagree with them. Do you think the lack of code reviews was a bad thing? I think if there’s going to be any oversight of new people, then it should be continuous rather than chunky. For me I don’t mind too much, I could go out and get oversight if I wanted it, and in those situations I felt comfortable without it. If I was managing the new person, then maybe I’d be keener on oversight and then the right way to do it is continuously and in very, very small chunks. Have you had any significant projects you’ve worked on outside of a job? When I was a teenager I wrote all sorts of stuff. I used to write games, I derived how to do isomorphic projections myself once. I didn’t know what the word was so I couldn’t Google for it, so I worked it out myself. It was horrifically complicated. But it sort of tailed off when I started at university, and is now basically zero. If I do side-projects now, they tend to be work-related side projects like my actors framework, NAct, which I started in a down tools week. Could you explain a little more about NAct? It is a little C# framework for writing parallel code more easily. Parallel programming is difficult when you need to write to shared data. Sometimes parallel programming is easy because you don’t need to write to shared data. When you do need to access shared data, you could just have your threads pile in and do their work, but then you would screw up the data because the threads would trample on each other’s toes. You could lock, but locks are really dangerous if you’re using more than one of them. You get interactions like deadlocks, and that’s just nasty. Actors instead allows you to say this piece of data belongs to this thread of execution, and nobody else can read it. If you want to read it, then ask that thread of execution for a piece of it by sending a message, and it will send the data back by a message. And that avoids deadlocks as long as you follow some obvious rules about not making your actors sit around waiting for other actors to do something. There are lots of ways to write actors, NAct allows you to do it as if it was method calls on other objects, which means you get all the strong type-safety that C# programmers like. Do you think that this is suitable for the majority of parallel programming, or do you think it’s only suitable for specific cases? It’s suitable for most difficult parallel programming. If you’ve just got a hundred web requests which are all independent of each other, then I wouldn’t bother because it’s easier to just spin them up in separate threads and they can proceed independently of each other. But where you’ve got difficult parallel programming, where you’ve got multiple threads accessing multiple bits of data in multiple ways at different times, then actors is at least as good as all other ways, and is, I reckon, easier to think about. When you’re using actors, you presumably still have to write your code in a different way from you would otherwise using single-threaded code. You can’t use actors with any methods that have return types, because you’re not allowed to call into another actor and wait for it. If you want to get a piece of data out of another actor, then you’ve got to use tasks so that you can use “async” and “await” to await asynchronously for it. But other than that, you can still stick things in classes so it’s not too different really. Rather than having thousands of objects with mutable state, you can use component-orientated design, where there are only a few mutable classes which each have a small number of instances. Then there can be thousands of immutable objects. If you tend to do that anyway, then actors isn’t much of a jump. If I’ve already built my system without any parallelism, how hard is it to add actors to exploit all eight cores on my desktop? Usually pretty easy. If you can identify even one boundary where things look like messages and you have components where some objects live on one side and these other objects live on the other side, then you can have a granddaddy object on one side be an actor and it will parallelise as it goes across that boundary. Not too difficult. If we do get 1000-core desktop PCs, do you think actors will scale up? It’s hard. There are always in the order of twenty to fifty actors in my whole program because I tend to write each component as actors, and I tend to have one instance of each component. So this won’t scale to a thousand cores. What you can do is write data structures out of actors. I use dictionaries all over the place, and if you need a dictionary that is going to be accessed concurrently, then you could build one of those out of actors in no time. You can use queuing to marshal requests between different slices of the dictionary which are living on different threads. So it’s like a distributed hash table but all of the chunks of it are on the same machine. That means that each of these thousand processors has cached one small piece of the dictionary. I reckon it wouldn’t be too big a leap to start doing proper parallelism. Do you think it helps if actors get baked into the language, similarly to Erlang? Erlang is excellent in that it has thread-local garbage collection. C# doesn’t, so there’s a limit to how well C# actors can possibly scale because there’s a single garbage collected heap shared between all of them. When you do a global garbage collection, you’ve got to stop all of the actors, which is seriously expensive, whereas in Erlang garbage collections happen per-actor, so they’re insanely cheap. However, Erlang deviated from all the sensible language design that people have used recently and has just come up with crazy stuff. You can definitely retrofit thread-local garbage collection to .NET, and then it’s quite well-suited to support actors, even if it’s not baked into the language. Speaking of language design, do you have a favourite programming language? I’ll choose a language which I’ve never written before. I like the idea of Scala. It sounds like C#, only with some of the niggles gone. I enjoy writing static types. It means you don’t have to writing tests so much. When you say it doesn’t have some of the niggles? C# doesn’t allow the use of a property as a method group. It doesn’t have Scala case classes, or sum types, where you can do a switch statement and the compiler checks that you’ve checked all the cases, which is really useful in functional-style programming. Pattern-matching, in other words. That’s actually the major niggle. C# is pretty good, and I’m quite happy with C#. And what about going even further with the type system to remove the need for tests to something like Haskell? Or is that a step too far? I’m quite a pragmatist, I don’t think I could deal with trying to write big systems in languages with too few other users, especially when learning how to structure things. I just don’t know anyone who can teach me, and the Internet won’t teach me. That’s the main reason I wouldn’t use it. If I turned up at a company that writes big systems in Haskell, I would have no objection to that, but I wouldn’t instigate it. What about things in C#? For instance, there’s contracts in C#, so you can try to statically verify a bit more about your code. Do you think that’s useful, or just not worthwhile? I’ve not really tried it. My hunch is that it needs to be built into the language and be quite mathematical for it to work in real life, and that doesn’t seem to have ended up true for C# contracts. I don’t think anyone who’s tried them thinks they’re any good. I might be wrong. On a slightly different note, how do you like to debug code? I think I’m quite an odd debugger. I use guesswork extremely rarely, especially if something seems quite difficult to debug. I’ve been bitten spending hours and hours on guesswork and not being scientific about debugging in the past, so now I’m scientific to a fault. What I want is to see the bug happening in the debugger, to step through the bug happening. To watch the program going from a valid state to an invalid state. When there’s a bug and I can’t work out why it’s happening, I try to find some piece of evidence which places the bug in one section of the code. From that experiment, I binary chop on the possible causes of the bug. I suppose that means binary chopping on places in the code, or binary chopping on a stage through a processing cycle. Basically, I’m very stupid about how I debug. I won’t make any guesses, I won’t use any intuition, I will only identify the experiment that’s going to binary chop most effectively and repeat rather than trying to guess anything. I suppose it’s quite top-down. Is most of the time then spent in the debugger? Absolutely, if at all possible I will never debug using print statements or logs. I don’t really hold much stock in outputting logs. If there’s any bug which can be reproduced locally, I’d rather do it in the debugger than outputting logs. And with SmartAssembly error reporting, there’s not a lot that can’t be either observed in an error report and just fixed, or reproduced locally. And in those other situations, maybe I’ll use logs. But I hate using logs. You stare at the log, trying to guess what’s going on, and that’s exactly what I don’t like doing. You have to just look at it and see does this look right or wrong. We’ve covered how you get to grip with bugs. How do you get to grips with an entire codebase? I watch it in the debugger. I find little bugs and then try to fix them, and mostly do it by watching them in the debugger and gradually getting an understanding of how the code works using my process of binary chopping. I have to do a lot of reading and watching code to choose where my slicing-in-half experiment is going to be. The last time I did it was SmartAssembly. The old code was a complete mess, but at least it did things top to bottom. There wasn’t too much of some of the big abstractions where flow of control goes all over the place, into a base class and back again. Code’s really hard to understand when that happens. So I like to choose a little bug and try to fix it, and choose a bigger bug and try to fix it. Definitely learn by doing. I want to always have an aim so that I get a little achievement after every few hours of debugging. Once I’ve learnt the codebase I might be able to fix all the bugs in an hour, but I’d rather be using them as an aim while I’m learning the codebase. If I was a maintainer of a codebase, what should I do to make it as easy as possible for you to understand? Keep distinct concepts in different places. And name your stuff so that it’s obvious which concepts live there. You shouldn’t have some variable that gets set miles up the top of somewhere, and then is read miles down to choose some later behaviour. I’m talking from a very much SmartAssembly point of view because the old SmartAssembly codebase had tons and tons of these things, where it would read some property of the code and then deal with it later. Just thousands of variables in scope. Loads of things to think about. If you can keep concepts separate, then it aids me in my process of fixing bugs one at a time, because each bug is going to more or less be understandable in the one place where it is. And what about tests? Do you think they help at all? I’ve never had the opportunity to learn a codebase which has had tests, I don’t know what it’s like! What about when you’re actually developing? How useful do you find tests in finding bugs or regressions? Finding regressions, absolutely. Running bits of code that would be quite hard to run otherwise, definitely. It doesn’t happen very often that a test finds a bug in the first place. I don’t really buy nebulous promises like tests being a good way to think about the spec of the code. My thinking goes something like “This code works at the moment, great, ship it! Ah, there’s a way that this code doesn’t work. Okay, write a test, demonstrate that it doesn’t work, fix it, use the test to demonstrate that it’s now fixed, and keep the test for future regressions.” The most valuable tests are for bugs that have actually happened at some point, because bugs that have actually happened at some point, despite the fact that you think you’ve fixed them, are way more likely to appear again than new bugs are. Does that mean that when you write your code the first time, there are no tests? Often. The chance of there being a bug in a new feature is relatively unaffected by whether I’ve written a test for that new feature because I’m not good enough at writing tests to think of bugs that I would have written into the code. So not writing regression tests for all of your code hasn’t affected you too badly? There are different kinds of features. Some of them just always work, and are just not flaky, they just continue working whatever you throw at them. Maybe because the type-checker is particularly effective around them. Writing tests for those features which just tend to always work is a waste of time. And because it’s a waste of time I’ll tend to wait until a feature has demonstrated its flakiness by having bugs in it before I start trying to test it. You can get a feel for whether it’s going to be flaky code as you’re writing it. I try to write it to make it not flaky, but there are some things that are just inherently flaky. And very occasionally, I’ll think “this is going to be flaky” as I’m writing, and then maybe do a test, but not most of the time. How do you think your programming style has changed over time? I’ve got clearer about what the right way of doing things is. I used to flip-flop a lot between different ideas. Five years ago I came up with some really good ideas and some really terrible ideas. All of them seemed great when I thought of them, but they were quite diverse ideas, whereas now I have a smaller set of reliable ideas that are actually good for structuring code. So my code is probably more similar to itself than it used to be back in the day, when I was trying stuff out. I’ve got more disciplined about encapsulation, I think. There are operational things like I use actors more now than I used to, and that forces me to use immutability more than I used to. The first code that I wrote in Red Gate was the memory profiler UI, and that was an actor, I just didn’t know the name of it at the time. I don’t really use object-orientation. By object-orientation, I mean having n objects of the same type which are mutable. I want a constant number of objects that are mutable, and they should be different types. I stick stuff in dictionaries and then have one thing that owns the dictionary and puts stuff in and out of it. That’s definitely a pattern that I’ve seen recently. I think maybe I’m doing functional programming. Possibly. It’s plausible. If you had to summarise the essence of programming in a pithy sentence, how would you do it? Programming is the form of art that, without losing any of the beauty of architecture or fine art, allows you to produce things that people love and you make money from. So you think it’s an art rather than a science? It’s a little bit of engineering, a smidgeon of maths, but it’s not science. Like architecture, programming is on that boundary between art and engineering. If you want to do it really nicely, it’s mostly art. You can get away with doing architecture and programming entirely by having a good engineering mind, but you’re not going to produce anything nice. You’re not going to have joy doing it if you’re an engineering mind. Architects who are just engineering minds are not going to enjoy their job. I suppose engineering is the foundation on which you build the art. Exactly. How do you think programming is going to change over the next ten years? There will be an unfortunate shift towards dynamically-typed languages, because of JavaScript. JavaScript has an unfair advantage. JavaScript’s unfair advantage will cause more people to be exposed to dynamically-typed languages, which means other dynamically-typed languages crop up and the best features go into dynamically-typed languages. Then people conflate the good features with the fact that it’s dynamically-typed, and more investment goes into dynamically-typed languages. They end up better, so people use them. What about the idea of compiling other languages, possibly statically-typed, to JavaScript? It’s a reasonable idea. I would like to do it, but I don’t think enough people in the world are going to do it to make it pick up. The hordes of beginners are the lifeblood of a language community. They are what makes there be good tools and what makes there be vibrant community websites. And any particular thing which is the same as JavaScript only with extra stuff added to it, although it might be technically great, is not going to have the hordes of beginners. JavaScript is always to be quickest and easiest way for a beginner to start programming in the browser. And dynamically-typed languages are great for beginners. Compilers are pretty scary and beginners don’t write big code. And having your errors come up in the same place, whether they’re statically checkable errors or not, is quite nice for a beginner. If someone asked me to teach them some programming, I’d teach them JavaScript. If dynamically-typed languages are great for beginners, when do you think the benefits of static typing start to kick in? The value of having a statically typed program is in the tools that rely on the static types to produce a smooth IDE experience rather than actually telling me my compile errors. And only once you’re experienced enough a programmer that having a really smooth IDE experience makes a blind bit of difference, does static typing make a blind bit of difference. So it’s not really about size of codebase. If I go and write up a tiny program, I’m still going to get value out of writing it in C# using ReSharper because I’m experienced with C# and ReSharper enough to be able to write code five times faster if I have that help. Any other visions of the future? Nobody’s going to use actors. Because everyone’s going to be running on single-core VMs connected over network-ready protocols like JSON over HTTP. So, parallelism within one operating system is going to die. But until then, you should use actors. More Red Gater Coder interviews

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  • Installing Lubuntu 14.04.1 forcepae fails

    - by Rantanplan
    I tried to install Lubuntu 14.04.1 from a CD. First, I chose Try Lubuntu without installing which gave: ERROR: PAE is disabled on this Pentium M (PAE can potentially be enabled with kernel parameter "forcepae" ... Following the description on https://help.ubuntu.com/community/PAE, I used forcepae and tried Try Lubuntu without installing again. That worked fine. dmesg | grep -i pae showed: [ 0.000000] Kernel command line: file=/cdrom/preseed/lubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- forcepae [ 0.008118] PAE forced! On the live-CD session, I tried installing Lubuntu double clicking on the install button on the desktop. Here, the CD starts running but then stops running and nothing happens. Next, I rebooted and tried installing Lubuntu directly from the boot menu screen using forcepae again. After a while, I receive the following error message: The installer encountered an unrecoverable error. A desktop session will now be run so that you may investigate the problem or try installing again. Hitting Enter brings me to the desktop. For what errors should I search? And how? Finally, I rebooted once more and tried Check disc for defects with forcepae option; no errors have been found. Now, I am wondering how to find the error or whether it would be better to follow advice c in https://help.ubuntu.com/community/PAE: "Move the hard disk to a computer on which the processor has PAE capability and PAE flag (that is, almost everything else than a Banias). Install the system as usual but don't add restricted drivers. After the install move the disk back." Thanks for some hints! Perhaps some of the following can help: On Lubuntu 12.04: cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 13 model name : Intel(R) Pentium(R) M processor 1.50GHz stepping : 6 microcode : 0x17 cpu MHz : 600.000 cache size : 2048 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr mce cx8 mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss tm pbe up bts est tm2 bogomips : 1284.76 clflush size : 64 cache_alignment : 64 address sizes : 32 bits physical, 32 bits virtual power management: uname -a Linux humboldt 3.2.0-67-generic #101-Ubuntu SMP Tue Jul 15 17:45:51 UTC 2014 i686 i686 i386 GNU/Linux lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 12.04.5 LTS Release: 12.04 Codename: precise cpuid eax in eax ebx ecx edx 00000000 00000002 756e6547 6c65746e 49656e69 00000001 000006d6 00000816 00000180 afe9f9bf 00000002 02b3b001 000000f0 00000000 2c04307d 80000000 80000004 00000000 00000000 00000000 80000001 00000000 00000000 00000000 00000000 80000002 20202020 20202020 65746e49 2952286c 80000003 6e655020 6d756974 20295228 7270204d 80000004 7365636f 20726f73 30352e31 007a4847 Vendor ID: "GenuineIntel"; CPUID level 2 Intel-specific functions: Version 000006d6: Type 0 - Original OEM Family 6 - Pentium Pro Model 13 - Stepping 6 Reserved 0 Brand index: 22 [not in table] Extended brand string: " Intel(R) Pentium(R) M processor 1.50GHz" CLFLUSH instruction cache line size: 8 Feature flags afe9f9bf: FPU Floating Point Unit VME Virtual 8086 Mode Enhancements DE Debugging Extensions PSE Page Size Extensions TSC Time Stamp Counter MSR Model Specific Registers MCE Machine Check Exception CX8 COMPXCHG8B Instruction SEP Fast System Call MTRR Memory Type Range Registers PGE PTE Global Flag MCA Machine Check Architecture CMOV Conditional Move and Compare Instructions FGPAT Page Attribute Table CLFSH CFLUSH instruction DS Debug store ACPI Thermal Monitor and Clock Ctrl MMX MMX instruction set FXSR Fast FP/MMX Streaming SIMD Extensions save/restore SSE Streaming SIMD Extensions instruction set SSE2 SSE2 extensions SS Self Snoop TM Thermal monitor 31 reserved TLB and cache info: b0: unknown TLB/cache descriptor b3: unknown TLB/cache descriptor 02: Instruction TLB: 4MB pages, 4-way set assoc, 2 entries f0: unknown TLB/cache descriptor 7d: unknown TLB/cache descriptor 30: unknown TLB/cache descriptor 04: Data TLB: 4MB pages, 4-way set assoc, 8 entries 2c: unknown TLB/cache descriptor On Lubuntu 14.04.1 live-CD with forcepae: cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 13 model name : Intel(R) Pentium(R) M processor 1.50GHz stepping : 6 microcode : 0x17 cpu MHz : 600.000 cache size : 2048 KB physical id : 0 siblings : 1 core id : 0 cpu cores : 1 apicid : 0 initial apicid : 0 fdiv_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss tm pbe bts est tm2 bogomips : 1284.68 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 32 bits virtual power management: uname -a Linux lubuntu 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:12 UTC 2014 i686 i686 i686 GNU/Linux lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 14.04.1 LTS Release: 14.04 Codename: trusty cpuid CPU 0: vendor_id = "GenuineIntel" version information (1/eax): processor type = primary processor (0) family = Intel Pentium Pro/II/III/Celeron/Core/Core 2/Atom, AMD Athlon/Duron, Cyrix M2, VIA C3 (6) model = 0xd (13) stepping id = 0x6 (6) extended family = 0x0 (0) extended model = 0x0 (0) (simple synth) = Intel Pentium M (Dothan B1) / Celeron M (Dothan B1), 90nm miscellaneous (1/ebx): process local APIC physical ID = 0x0 (0) cpu count = 0x0 (0) CLFLUSH line size = 0x8 (8) brand index = 0x16 (22) brand id = 0x16 (22): Intel Pentium M, .13um feature information (1/edx): x87 FPU on chip = true virtual-8086 mode enhancement = true debugging extensions = true page size extensions = true time stamp counter = true RDMSR and WRMSR support = true physical address extensions = false machine check exception = true CMPXCHG8B inst. = true APIC on chip = false SYSENTER and SYSEXIT = true memory type range registers = true PTE global bit = true machine check architecture = true conditional move/compare instruction = true page attribute table = true page size extension = false processor serial number = false CLFLUSH instruction = true debug store = true thermal monitor and clock ctrl = true MMX Technology = true FXSAVE/FXRSTOR = true SSE extensions = true SSE2 extensions = true self snoop = true hyper-threading / multi-core supported = false therm. monitor = true IA64 = false pending break event = true feature information (1/ecx): PNI/SSE3: Prescott New Instructions = false PCLMULDQ instruction = false 64-bit debug store = false MONITOR/MWAIT = false CPL-qualified debug store = false VMX: virtual machine extensions = false SMX: safer mode extensions = false Enhanced Intel SpeedStep Technology = true thermal monitor 2 = true SSSE3 extensions = false context ID: adaptive or shared L1 data = false FMA instruction = false CMPXCHG16B instruction = false xTPR disable = false perfmon and debug = false process context identifiers = false direct cache access = false SSE4.1 extensions = false SSE4.2 extensions = false extended xAPIC support = false MOVBE instruction = false POPCNT instruction = false time stamp counter deadline = false AES instruction = false XSAVE/XSTOR states = false OS-enabled XSAVE/XSTOR = false AVX: advanced vector extensions = false F16C half-precision convert instruction = false RDRAND instruction = false hypervisor guest status = false cache and TLB information (2): 0xb0: instruction TLB: 4K, 4-way, 128 entries 0xb3: data TLB: 4K, 4-way, 128 entries 0x02: instruction TLB: 4M pages, 4-way, 2 entries 0xf0: 64 byte prefetching 0x7d: L2 cache: 2M, 8-way, sectored, 64 byte lines 0x30: L1 cache: 32K, 8-way, 64 byte lines 0x04: data TLB: 4M pages, 4-way, 8 entries 0x2c: L1 data cache: 32K, 8-way, 64 byte lines extended feature flags (0x80000001/edx): SYSCALL and SYSRET instructions = false execution disable = false 1-GB large page support = false RDTSCP = false 64-bit extensions technology available = false Intel feature flags (0x80000001/ecx): LAHF/SAHF supported in 64-bit mode = false LZCNT advanced bit manipulation = false 3DNow! PREFETCH/PREFETCHW instructions = false brand = " Intel(R) Pentium(R) M processor 1.50GHz" (multi-processing synth): none (multi-processing method): Intel leaf 1 (synth) = Intel Pentium M (Dothan B1), 90nm

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  • Microsoft TechEd 2010 - Day 3 @ Bangalore

    - by sathya
    Microsoft TechEd 2010 - Day 3 @ Bangalore Sorry for my delayed post on day 3 because I had to travel from Blore to Chennai So I couldnt write for the past two days. On day 3 as usual we had lot of simultaneous tracks on various sessions. This day I choose the Your Data, Our Platform Track. It had sessions on the following 5 topics :   Developing Data-tier Applications in Visual Studio 2010 - by Sanjay Nagamangalam SQL Server Query Optimization, Execution and Debugging Query Performance - by Vinod Kumar M SQL Server Utility - Its about more than 1 SQL Server - by Vinod Kumar Jagannathan Data Recovery / Consistency with CheckDB - by Vinod Kumar M Developing with SQL Server Spatial and Deep dive into Spatial Indexing - by Pinal Dave Developing Data-tier Applications in Visual Studio 2010 - by Sanjay Nagamangalam This was one of the superb sessions i have attended. He explained all the concepts in detail with a demo. The important thing in this is there is something called Data-Tier application project which is newly introduced in this VS2010 with which we can manage all our data along with our application inside our VS itself. We can create DB,Tables,Procs,Views etc. here itself and once we deploy it creates a compressed file called .dacpac which stores all the changes in Table Schema,Created procs, etc. on to that single file which reduces our (developer's) effort in preparing the deployment scripts and giving it to the DBA. It also has some policy configurations which can be managed easily by checking some rules like in outlook. For Ex : IF the SQL Server Version > 10 then deploy else dont. This rule specifies that even if we try to deploy on SQL Server DB with version less than 10 It will not do it. And if we deploy some .dacpac to SQL server production db with the option upgrade DB with this dacpac once everything completes successfully it will say success else it rollsback to the prior version. Even if it gets deployed successfully and later @ a point of time you wish to revert it back to the prior version, you can go ahead and delete the existing dacpac version so that it reverts to the older version of the db changes. And for the good questions that were asked in the session T-Shirts were given. SQL Server Query Optimization, Execution and Debugging Query Performance - by Vinod Kumar M This one too was the best session. The speaker Vinod explained everything very much clearly. This was really useful session and you dont believe, as per my knowledge, in the total 3 days in the TechEd except the Keynote, for this session seats were full (House FULL)  People were even standing out to attend this session. Such a great one it was. The speaker did a deep dive in to the Query Plan section and showed which actually causes the problem. Its all about the thing that we need to understand about the execution of SQL server Queries. We think in a way and SQL Server never executes in that way. We need to understand that first. He also told about there might be two plans generated for a single query at a point of time because of parallel processors in the system. The Key is here in every query. There is something called Estimated Row Count and Actual Row Count in the query plan. If the estimated row count by SQL server tallies with the actual row count your performance will be awesome. He said some tweaks to achieve the same. After this as usual we had lunch SQL Server Utility - Its about more than 1 SQL Server - by Vinod Kumar Jagannathan This was more of a DBA's session. Am really sorry I was totally blank and I was not interested to attend this session and walked out to attend Migrating to the cloud by Harish Ranganathan (My favorite Speaker) but unfortunately that was some other persons session. There the speaker was telling about how to configure the connection strings in such a way that we can connect to the SQL Azure platform from our VS and also showed us how to deploy the same in to Windows Azure. In between there were lot of technical problems like laptop hang, user locked and he was switching between systems, also i came in the half so i wasnt able to listen that fully. In between, Since I got an MCTS certification they gave me T-Shirt with the lines 'Iam Certified. Are you?' and they asked me to wear that. If we wear that we might get spotted and they would give us some goodies  So on the 3rd day I was wearing that T-Shirt. I got spotted by the person Tarun who was coordinating things about the certification, and he was accompanied with a cameraman and they interviewed me about the certification and I was shown live in the Teched and was seen by 60000 live viewers of the TechEd. I was really happy on that. Data Recovery / Consistency with CheckDB - by Vinod Kumar M This was one of the best sessions too in the TechEd. This guy is really amazing. In front of us he crashed a DB and showed how to recover the same in 6 different ways for different no of failures. Showed about Different types of error msgs like : 823,824,825 msdb..suspect_pages DBCC CheckDB (different parameters to it) I am really waiting for his session to get uploaded live in the Teched Website. Here is his contact info If you wish to connect to him : Twitter : @vinodk_sql Website : www.ExtremeExperts.com Blog : http://blogs.sqlxml.org/vinodkumar Developing with SQL Server Spatial and Deep dive into Spatial Indexing - by Pinal Dave Pinal Dave is a King in SQL and he is a SQL MVP and he is the owner of SQLAuthority.com He took the session on Spatial Databases from the start. Showed about the different types of Spatial : Geometric and Geographic Geometric : x and y axis its a planar surface Geographic : Spherical surface with 3600  as the maximum which is used to represent the geographic points on the earth and easy to draw maps of different kinds. He had a lot of obstacles during his session like rain coming inside the hall, mic wires got bursted due to rain, Videos off on the display screens. In spite of that he asked the audience to come in the front rows and managed to take a good session without ppts and finally we got the displays on and he was showing demos on the same what he explained orally. That was really a fun filled informative session. He gave some books for the persons who asked good questions and answered well for his questions and I got one too  (It was a book on Data Mining - Wrox Publishers) And finally after all these things there was Keynote session for close of the TechEd. and we all assembled in a big hall where Mr.Ashok Soota, a man of age around 70  co-founder of Mindtree was called to give some lecture on his successes. He was explaining about his past and what all companies he switched and for what reasons and what are all his successes and what are all his failures and the learnings of him from his past failures. and his success and failures on his partnerships with the other concern. And there were some questions for him like What is your suggestion on young entrepreneur? How did you learn from past failures? What is reiterating your success? What is your suggestion on partnerships? How to choose partnerships? etc. And they said @ 7.30 Pm there would be a party night, but unfortunately i was not able to attend that because I had to catch my train and before that i had to pack things, so I started @ 7 itself. Thats it about the TechED!!! Stay tuned for further Technology updates.

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