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• The first day of JavaOne is already over!

  - by delabassee

  In the past Sunday used to be a more relaxing day with ‘just’ some JavaOne activities going on. Sunday used to be a soft day to prepare yourself for an exhausting week. This is now over as JavaOne is expanding; Sunday is now an integral part of the conference. One of the side effect of this extra day is that some activities related to JavaOne and OpenWorld such as MySQL Connect are being push to start a day earlier on Saturday (can you spot the pattern here?). On the GlassFish front, Sunday was a very busy day! It started at the Moscone Center with the annual GlassFish Community Event where the Java EE 7 and GF 4 roadmaps were presented and discussed. During the event, different GlassFish users such as ZeroTurnaround (the JRebel guys), Grupo RBS and IDR Solutions shared their views on GF, why they like GF but also what could be improved. The event was also a forum for the GF community to exchange with some of the key Java EE / GlassFish Oracle Executives and the different GF team members. The Strategy keynote and the Technical keynote were held in the Masonic Auditorium later in the after-noon. Oracle executives have presented the plans for Java SE, Java FX and Java EE. As on-demand replays will be available soon, I will not summarize several hours of content but here are some personal takeaways from those keynotes. Modularity Modularity is a big deal. We know by now that Project Jigsaw will not be ready for Java SE 8 but in any case, it is already possible (and encouraged) to test Jigsaw today. In the future, Java EE plan to rely on the modularity features provided by Java SE, so Project Jigsaw is also relevant for Java EE developers. Shorter term, to cover some of the modular requirements, Java SE will adopt the approach that was used for Java EE 6 and the notion of Profiles. This approach does not define a module system per say; Profiles is a way to clearly define different subsets of Java SE to fulfill different needs (e.g. the full JRE is not required for a headless application). The introduction of different Profiles, from the Base profile (10mb) to the Full Profile (+50mb), has been proposed for Java SE 8. Embedded Embedded is a strong theme going forward for the Java Plaform. There is now a dedicated program : Java Embedded @ JavaOne Java by nature (e.g. platform independence, built-in security, ability easily talks to any back-end systems, large set of skills available on the market, etc.) is probably the most suited platform for the Internet of Things. You can quickly be up-to-speed and develop services and applications for that space just by using your current Java skills. All you need to start developing on ARM is a 35$ Raspberry Pi ARM board (25$ if you are cheap and can live without an ethernet connection) and the recently released JDK for Linux/ARM. Obviously, GlassFish runs on Raspberry Pi. If you wan to go further in the embedded space, you should take a look Java SE Embedded, an optimized, low footprint, Java environment that support the major embedded architectures (ARM, PPC and x86). Finally, Oracle has recently introduced Java Embedded Suite, a new solution that brings modern middleware capabilities to the embedded space. Java Embedded Suite is an optimized solution that leverage Java SE Embedded but also GlassFish, Jersey and JavaDB to deploy advanced value added capabilities (eg. sensor data filtering and) deeper in the network, closer to the devices. JavaFX JavaFX is going strong! Starting from Java SE 7u6, JavaFX is bundled with the JDK. JavaFX is now available for all the major desktop platforms (Windows, Linux and Mac OS X). JavaFX is now also available, in developer preview, for low end device running Linux/ARM. During the keynote, JavaFX was shown running on a Raspberry Pi! And as announced during the keynote, JavaFX should be fully open-sourced by the end of the year; contributions are welcome!. There is a strong momentum around JavaFX, it’s the ideal client solution for the Java platform. A client layer that works perfectly with GlassFish on the back-end. If you were not convince by JavaFX, it’s time to reconsider it! As an old Chinese proverb say “One tweet is worth a thousand words!” HTML5, Project Avatar and Java EE 7 HTML5 got a lot of airtime too, it was covered during the Java EE 7 section of the keynote. Some details about Project Avatar, Oracle’s incubator project for a TSA (Thin Server Architecture) solution, were diluted and shown during the keynote. On the tooling side, Project Easel running on NetBeans 7.3 beta was demo’ed, including a cool NetBeans debugging session running in Chrome! HTML 5, Project Avatar and Java EE 7 deserve separate posts... Feedback We need your feedback! There are many projects, JSRs and products cooking : GlassFish 4, Project Jigsaw, Concurrency Utilities for Java EE (JSR 236), OpenJFX, OpenJDK to name just a few. Those projects, those specifications will have a profound impact on the Java platform for the years to come! So if you have the opportunity, download, install, learn, tests them and give feedback! Remember, you can "Make the Future Java!" Finally, the traditional GlassFish Party at the Thirsty Bear concluded the first JavaOne day. This party is another place where the community can freely exchange with the GlassFish team in a more relaxed, more friendly (but sometime more noisy) atmosphere. Arun has posted a set of pictures to reflect the atmosphere of the keynotes and the GlassFish party. You can find more details on the others Java EE and GlassFish activities here.

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• A deadlock was detected while trying to lock variables in SSIS

  Error: 0xC001405C at SQL Log Status: A deadlock was detected while trying to lock variables "User::RowCount" for read/write access. A lock cannot be acquired after 16 attempts. The locks timed out. Have you ever considered variable locking when building your SSIS packages? I expect many people haven’t just because most of the time you never see an error like the one above. I’ll try and explain a few key concepts about variable locking and hopefully you never will see that error. First of all, what is all this variable locking all about? Put simply SSIS variables have to be locked before they can be accessed, and then of course unlocked once you have finished with them. This is baked into SSIS, presumably to reduce the risk of race conditions, but with that comes some additional overhead in that you need to be careful to avoid lock conflicts in some scenarios. The most obvious place you will come across any hint of locking (no pun intended) is the Script Task or Script Component with their ReadOnlyVariables and ReadWriteVariables properties. These two properties allow you to enter lists of variables to be used within the task, or to put it another way, these lists of variables to be locked, so that they are available within the task. During the task pre-execute phase the variables and locked, you then use them during the execute phase when you code is run, and then unlocked for you during the post-execute phase. So by entering the variable names in one of the two list, the locking is taken care of for you, and you just read and write to the Dts.Variables collection that is exposed in the task for the purpose. As you can see in the image above, the variable PackageInt is specified, which means when I write the code inside that task I don’t have to worry about locking at all, as shown below. public void Main() { // Set the variable value to something new Dts.Variables["PackageInt"].Value = 199; // Raise an event so we can play in the event handler bool fireAgain = true; Dts.Events.FireInformation(0, "Script Task Code", "This is the script task raising an event.", null, 0, ref fireAgain); Dts.TaskResult = (int)ScriptResults.Success; } As you can see as well as accessing the variable, hassle free, I also raise an event. Now consider a scenario where I have an event hander as well as shown below. Now what if my event handler uses tries to use the same variable as well? Well obviously for the point of this post, it fails with the error quoted previously. The reason why is clearly illustrated if you consider the following sequence of events. Package execution starts Script Task in Control Flow starts Script Task in Control Flow locks the PackageInt variable as specified in the ReadWriteVariables property Script Task in Control Flow executes script, and the On Information event is raised The On Information event handler starts Script Task in On Information event handler starts Script Task in On Information event handler attempts to lock the PackageInt variable (for either read or write it doesn’t matter), but will fail because the variable is already locked. The problem is caused by the event handler task trying to use a variable that is already locked by the task in Control Flow. Events are always raised synchronously, therefore the task in Control Flow that is raising the event will not regain control until the event handler has completed, so we really do have un-resolvable locking conflict, better known as a deadlock. In this scenario we can easily resolve the problem by managing the variable locking explicitly in code, so no need to specify anything for the ReadOnlyVariables and ReadWriteVariables properties. public void Main() { // Set the variable value to something new, with explicit lock control Variables lockedVariables = null; Dts.VariableDispenser.LockOneForWrite("PackageInt", ref lockedVariables); lockedVariables["PackageInt"].Value = 199; lockedVariables.Unlock(); // Raise an event so we can play in the event handler bool fireAgain = true; Dts.Events.FireInformation(0, "Script Task Code", "This is the script task raising an event.", null, 0, ref fireAgain); Dts.TaskResult = (int)ScriptResults.Success; } Now the package will execute successfully because the variable lock has already been released by the time the event is raised, so no conflict occurs. For those of you with a SQL Engine background this should all sound strangely familiar, and boils down to getting in and out as fast as you can to reduce the risk of lock contention, be that SQL pages or SSIS variables. Unfortunately we cannot always manage the locking ourselves. The Execute SQL Task is very often used in conjunction with variables, either to pass in parameter values or get results out. Either way the task will manage the locking for you, and will fail when it cannot lock the variables it requires. The scenario outlined above is clear cut deadlock scenario, both parties are waiting on each other, so it is un-resolvable. The mechanism used within SSIS isn’t actually that clever, and whilst the message says it is a deadlock, it really just means it tried a few times, and then gave up. The last part of the error message is actually the most accurate in terms of the failure, A lock cannot be acquired after 16 attempts. The locks timed out.  Now this may come across as a recommendation to always manage locking manually in the Script Task or Script Component yourself, but I think that would be an overreaction. It is more of a reminder to be aware that in high concurrency scenarios, especially when sharing variables across multiple objects, locking is important design consideration. Update – Make sure you don’t try and use explicit locking as well as leaving the variable names in the ReadOnlyVariables and ReadWriteVariables lock lists otherwise you’ll get the deadlock error, you cannot lock a variable twice!

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• JavaOne 2012 Sunday Strategy Keynote

  - by Janice J. Heiss

  At the Sunday Strategy Keynote, held at the Masonic Auditorium, Hasan Rizvi, EVP, Middleware and Java Development, stated that the theme for this year's JavaOne is: “Make the future Java”-- meaning that Java continues in its role as the most popular, complete, productive, secure, and innovative development platform. But it also means, he qualified, the process by which we make the future Java -- an open, transparent, collaborative, and community-driven evolution. "Many of you have bet your businesses and your careers on Java, and we have bet our business on Java," he said.Rizvi detailed the three factors they consider critical to the success of Java--technology innovation, community participation, and Oracle's leadership/stewardship. He offered a scorecard in these three realms over the past year--with OS X and Linux ARM support on Java SE, open sourcing of JavaFX by the end of the year, the release of Java Embedded Suite 7.0 middleware platform, and multiple releases on the Java EE side. The JCP process continues, with new JSR activity, and JUGs show a 25% increase in participation since last year. Oracle, meanwhile, continues its commitment to both technology and community development/outreach--with four regional JavaOne conferences last year in various part of the world, as well as the release of Java Magazine, with over 120,000 current subscribers. Georges Saab, VP Development, Java SE, next reviewed features of Java SE 7--the first major revision to the platform under Oracle's stewardship, which has included near-monthly update releases offering hundreds of fixes, performance enhancements, and new features. Saab indicated that developers, ISVs, and hosting providers have all been rapid adopters of the platform. He also noted that Oracle's entire Fusion middleware stack is supported on SE 7. The supported platforms for SE 7 has also increased--from Windows, Linux, and Solaris, to OS X, Linux ARM, and the emerging ARM micro-server market. "In the last year, we've added as many new platforms for Java, as were added in the previous decade," said Saab.Saab also explored the upcoming JDK 8 release--including Project Lambda, Project Nashorn (a modern implementation of JavaScript running on the JVM), and others. He noted that Nashorn functionality had already been used internally in NetBeans 7.3, and announced that they were planning to contribute the implementation to OpenJDK. Nandini Ramani, VP Development, Java Client, ME and Card, discussed the latest news pertaining to JavaFX 2.0--releases on Windows, OS X, and Linux, release of the FX Scene Builder tool, the JavaFX WebView component in NetBeans 7.3, and an OpenJFX project in OpenJDK. Nandini announced, as of Sunday, the availability for download of JavaFX on Linux ARM (developer preview), as well as Scene Builder on Linux. She noted that for next year's JDK 8 release, JavaFX will offer 3D, as well as third-party component integration. Avinder Brar, Senior Software Engineer, Navis, and Dierk König, Canoo Fellow, next took the stage and demonstrated all that JavaFX offers, with a feature-rich, animation-rich, real-time cargo management application that employs Canoo's just open-sourced Dolphin technology.Saab also explored Java SE 9 and beyond--Jigsaw modularity, Penrose Project for interoperability with OSGi, improved multi-tenancy for Java in the cloud, and Project Sumatra. Phil Rogers, HSA Foundation President and AMD Corporate Fellow, explored heterogeneous computing platforms that combine the CPU and the parallel processor of the GPU into a single piece of silicon and shared memory—a hardware technology driven by such advanced functionalities as HD video, face recognition, and cloud workloads. Project Sumatra is an OpenJDK project targeted at bringing Java to such heterogeneous platforms--with hardware and software experts working together to modify the JVM for these advanced applications and platforms.Ramani next discussed the latest with Java in the embedded space--"the Internet of things" and M2M--declaring this to be "the next IT revolution," with Java as the ideal technology for the ecosystem. Last week, Oracle released Java ME Embedded 3.2 (for micro-contollers and low-power devices), and Java Embedded Suite 7.0 (a middleware stack based on Java SE 7). Axel Hansmann, VP Strategy and Marketing, Cinterion, explored his company's use of Java in M2M, and their new release of EHS5, the world's smallest 3G-capable M2M module, running Java ME Embedded. Hansmaan explained that Java offers them the ability to create a "simple to use, scalable, coherent, end-to-end layer" for such diverse edge devices.Marc Brule, Chief Financial Office, Royal Canadian Mint, also explored the fascinating use-case of JavaCard in his country's MintChip e-cash technology--deployable on smartphones, USB device, computer, tablet, or cloud. In parting, Ramani encouraged developers to download the latest releases of Java Embedded, and try them out.Cameron Purdy, VP, Fusion Middleware Development and Java EE, summarized the latest developments and announcements in the Enterprise space--greater developer productivity in Java EE6 (with more on the way in EE 7), portability between platforms, vendors, and even cloud-to-cloud portability. The earliest version of the Java EE 7 SDK is now available for download--in GlassFish 4--with WebSocket support, better JSON support, and more. The final release is scheduled for April of 2013. Nicole Otto, Senior Director, Consumer Digital Technology, Nike, explored her company's Java technology driven enterprise ecosystem for all things sports, including the NikeFuel accelerometer wrist band. Looking beyond Java EE 7, Purdy mentioned NoSQL database functionality for EE 8, the concurrency utilities (possibly in EE 7), some of the Avatar projects in EE 7, some in EE 8, multi-tenancy for the cloud, supporting SaaS applications, and more.Rizvi ended by introducing Dr. Robert Ballard, oceanographer and National Geographic Explorer in Residence--part of Oracle's philanthropic relationship with the National Geographic Society to fund K-12 education around ocean science and conservation. Ballard is best known for having discovered the wreckage of the Titanic. He offered a fascinating video and overview of the cutting edge technology used in such deep-sea explorations, noting that in his early days, high-bandwidth exploration meant that you’d go down in a submarine and "stick your face up against the window." Now, it's a remotely operated, technology telepresence--"I think of my Hercules vehicle as my equivalent of a Na'vi. When I go beneath the sea, I actually send my spirit." Using high bandwidth satellite links, such amazing explorations can now occur via smartphone, laptop, or whatever platform. Ballard’s team regularly offers live feeds and programming out to schools and the world, spanning 188 countries--with embedding educators as part of the expeditions. It's technology at its finest, inspiring the next-generation of scientists and explorers!

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• Performance triage

  - by Dave

  Folks often ask me how to approach a suspected performance issue. My personal strategy is informed by the fact that I work on concurrency issues. (When you have a hammer everything looks like a nail, but I'll try to keep this general). A good starting point is to ask yourself if the observed performance matches your expectations. Expectations might be derived from known system performance limits, prototypes, and other software or environments that are comparable to your particular system-under-test. Some simple comparisons and microbenchmarks can be useful at this stage. It's also useful to write some very simple programs to validate some of the reported or expected system limits. Can that disk controller really tolerate and sustain 500 reads per second? To reduce the number of confounding factors it's better to try to answer that question with a very simple targeted program. And finally, nothing beats having familiarity with the technologies that underlying your particular layer. On the topic of confounding factors, as our technology stacks become deeper and less transparent, we often find our own technology working against us in some unexpected way to choke performance rather than simply running into some fundamental system limit. A good example is the warm-up time needed by just-in-time compilers in Java Virtual Machines. I won't delve too far into that particular hole except to say that it's rare to find good benchmarks and methodology for java code. Another example is power management on x86. Power management is great, but it can take a while for the CPUs to throttle up from low(er) frequencies to full throttle. And while I love "turbo" mode, it makes benchmarking applications with multiple threads a chore as you have to remember to turn it off and then back on otherwise short single-threaded runs may look abnormally fast compared to runs with higher thread counts. In general for performance characterization I disable turbo mode and fix the power governor at "performance" state. Another source of complexity is the scheduler, which I've discussed in prior blog entries. Lets say I have a running application and I want to better understand its behavior and performance. We'll presume it's warmed up, is under load, and is an execution mode representative of what we think the norm would be. It should be in steady-state, if a steady-state mode even exists. On Solaris the very first thing I'll do is take a set of "pstack" samples. Pstack briefly stops the process and walks each of the stacks, reporting symbolic information (if available) for each frame. For Java, pstack has been augmented to understand java frames, and even report inlining. A few pstack samples can provide powerful insight into what's actually going on inside the program. You'll be able to see calling patterns, which threads are blocked on what system calls or synchronization constructs, memory allocation, etc. If your code is CPU-bound then you'll get a good sense where the cycles are being spent. (I should caution that normal C/C++ inlining can diffuse an otherwise "hot" method into other methods. This is a rare instance where pstack sampling might not immediately point to the key problem). At this point you'll need to reconcile what you're seeing with pstack and your mental model of what you think the program should be doing. They're often rather different. And generally if there's a key performance issue, you'll spot it with a moderate number of samples. I'll also use OS-level observability tools to lock for the existence of bottlenecks where threads contend for locks; other situations where threads are blocked; and the distribution of threads over the system. On Solaris some good tools are mpstat and too a lesser degree, vmstat. Try running "mpstat -a 5" in one window while the application program runs concurrently. One key measure is the voluntary context switch rate "vctx" or "csw" which reflects threads descheduling themselves. It's also good to look at the user; system; and idle CPU percentages. This can give a broad but useful understanding if your threads are mostly parked or mostly running. For instance if your program makes heavy use of malloc/free, then it might be the case you're contending on the central malloc lock in the default allocator. In that case you'd see malloc calling lock in the stack traces, observe a high csw/vctx rate as threads block for the malloc lock, and your "usr" time would be less than expected. Solaris dtrace is a wonderful and invaluable performance tool as well, but in a sense you have to frame and articulate a meaningful and specific question to get a useful answer, so I tend not to use it for first-order screening of problems. It's also most effective for OS and software-level performance issues as opposed to HW-level issues. For that reason I recommend mpstat & pstack as my the 1st step in performance triage. If some other OS-level issue is evident then it's good to switch to dtrace to drill more deeply into the problem. Only after I've ruled out OS-level issues do I switch to using hardware performance counters to look for architectural impediments.

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• How You Helped Shape Java EE 7...

  - by reza_rahman

  I have been working with the JCP in various roles since EJB 3/Java EE 5 (much of it on my own time), eventually culminating in my decision to accept my current role at Oracle (despite it's inevitable set of unique challenges, a role I find by and large positive and fulfilling). During these years, it has always been clear to me that pretty much everyone in the JCP genuinely cares about openness, feedback and developer participation. Perhaps the most visible sign to date of this high regard for grassroots level input is a survey on Java EE 7 gathered a few months ago. The survey was designed to get open feedback on a number of critical issues central to the Java EE 7 umbrella specification including what APIs to include in the standard. When we started the survey, I don't think anyone was certain what the level of participation from developers would really be. I also think everyone was pleasantly surprised that a large number of developers (around 1100) took the time out to vote on these very important issues that could impact their own professional life. And it wasn't just a matter of the quantity of responses. I was particularly impressed with the quality of the comments made through the survey (some of which I'll try to do justice to below). With Java EE 7 under our belt and the horizons for Java EE 8 emerging, this is a good time to thank everyone that took the survey once again for their thoughts and let you know what the impact of your voice actually was. As an aside, you may be happy to know that we are working hard behind the scenes to try to put together a similar survey to help kick off the agenda for Java EE 8 (although this is by no means certain). I'll break things down by the questions asked in the survey, the responses and the resulting change in the specification. APIs to Add to Java EE 7 Full/Web Profile The first question in the survey asked which of four new candidate APIs (WebSocket, JSON-P, JBatch and JCache) should be added to the Java EE 7 Full and Web profile respectively. Developers by and large wanted all the new APIs added to the full platform. The comments expressed particularly strong support for WebSocket and JCache. Others expressed dissatisfaction over the lack of a JSON binding (as opposed to JSON processing) API. WebSocket, JSON-P and JBatch are now part of Java EE 7. In addition, the long-awaited Java EE Concurrency Utilities API was also included in the Full Profile. Unfortunately, JCache was not finalized in time for Java EE 7 and the decision was made not to hold up the Java EE release any longer. JCache continues to move forward strongly and will very likely be included in Java EE 8 (it will be available much sooner than Java EE 8 to boot). An emergent standard for JSON-B is also a strong possibility for Java EE 8. When it came to the Web Profile, developers were supportive of adding WebSocket and JSON-P, but not JBatch and JCache. Both WebSocket and JSON-P are now part of the Web Profile, now also including the already popular JAX-RS API. Enabling CDI by Default The second question asked whether CDI should be enabled in Java EE by default. The overwhelming majority of developers supported the default enablement of CDI. In addition, developers expressed a desire for better CDI/Java EE alignment (with regards to EJB and JSF in particular). Some developers expressed legitimate concerns over the performance implications of enabling CDI globally as well as the potential conflict with other JSR 330 implementations like Spring and Guice. CDI is enabled by default in Java EE 7. Respecting the legitimate concerns, CDI 1.1 was very careful to add additional controls around component scanning. While a lot of work was done in Java EE 6 and Java EE 7 around CDI alignment, further alignment is under serious consideration for Java EE 8. Consistent Usage of @Inject The third question was around using CDI/JSR 330 @Inject consistently vs. allowing JSRs to create their own injection annotations (e.g. @BatchContext). A majority of developers wanted consistent usage of @Inject. The comments again reflected a strong desire for CDI/Java EE alignment. A lot of emphasis in Java EE 7 was put into using @Inject consistently. For example, the JBatch specification is focused on using @Inject wherever possible. JAX-RS remains an exception with it's existing custom injection annotations. However, the JAX-RS specification leads understand the importance of eventual convergence, hopefully in Java EE 8. Expanding the Use of @Stereotype The fourth question was about expanding CDI @Stereotype to cover annotations across Java EE beyond just CDI. A solid majority of developers supported the idea of making @Stereotype more universal in Java EE. The comments maintained the general theme of strong support for CDI/Java EE alignment Unfortunately, there was not enough time and resources in Java EE 7 to implement this fairly pervasive feature. However, it remains a serious consideration for Java EE 8. Expanding Interceptor Use The final set of questions was about expanding interceptors further across Java EE. Developers strongly supported the concept. Along with injection, interceptors are now supported across all Java EE 7 components including Servlets, Filters, Listeners, JAX-WS endpoints, JAX-RS resources, WebSocket endpoints and so on. I hope you are encouraged by how your input to the survey helped shape Java EE 7 and continues to shape Java EE 8. Participating in these sorts of surveys is of course just one way of contributing to Java EE. Another great way to stay involved is the Adopt-A-JSR Program. A large number of developers are already participating through their local JUGs. You could of course become a Java EE JSR expert group member or observer. You should stay tuned to The Aquarium for the progress of Java EE 8 JSRs if that's something you want to look into...

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• What Counts for A DBA - Logic

  - by drsql

  "There are 10 kinds of people in the world. Those who will always wonder why there are only two items in my list and those who will figured it out the first time they saw this very old joke."  Those readers who will give up immediately and get frustrated with me for not explaining it to them are not likely going to be great technical professionals of any sort, much less a programmer or administrator who will be constantly dealing with the common failures that make up a DBA's day.  Many of these people will stare at this like a dog staring at a traffic signal and still have no more idea of how to decipher the riddle. Without explanation they will give up, call the joke "stupid" and, feeling quite superior, walk away indignantly to their job likely flipping patties of meat-by-product. As a data professional or any programmer who has strayed  to this very data-oriented blog, you would, if you are worth your weight in air, either have recognized immediately what was going on, or felt a bit ignorant.  Your friends are chuckling over the joke, but why is it funny? Unfortunately you left your smartphone at home on the dresser because you were up late last night programming and were running late to work (again), so you will either have to fake a laugh or figure it out.  Digging through the joke, you figure out that the word "two" is the most important part, since initially the joke mentioned 10. Hmm, why did they spell out two, but not ten? Maybe 10 could be interpreted a different way?  As a DBA, this sort of logic comes into play every day, and sometimes it doesn't involve nerdy riddles or Star Wars folklore.  When you turn on your computer and get the dreaded blue screen of death, you don't immediately cry to the help desk and sit on your thumbs and whine about not being able to work. Do that and your co-workers will question your nerd-hood; I know I certainly would. You figure out the problem, and when you have it narrowed down, you call the help desk and tell them what the problem is, usually having to explain that yes, you did in fact try to reboot before calling.  Of course, sometimes humility does come in to play when you reach the end of your abilities, but the ‘end of abilities’ is not something any of us recognize readily. It is handy to have the ability to use logic to solve uncommon problems: It becomes especially useful when you are trying to solve a data-related problem such as a query performance issue, and the way that you approach things will tell your coworkers a great deal about your abilities.  The novice is likely to immediately take the approach of  trying to add more indexes or blaming the hardware. As you become more and more experienced, it becomes increasingly obvious that performance issues are a very complex topic. A query may be slow for a myriad of reasons, from concurrency issues, a poor query plan because of a parameter value (like parameter sniffing,) poor coding standards, or just because it is a complex query that is going to be slow sometimes. Some queries that you will deal with may have twenty joins and hundreds of search criteria, and it can take a lot of thought to determine what is going on.  You can usually figure out the problem to almost any query by using basic knowledge of how joins and queries work, together with the help of such things as the query plan, profiler or monitoring tools.  It is not unlikely that it can take a full day’s work to understand some queries, breaking them down into smaller queries to find a very tiny problem. Not every time will you actually find the problem, and it is part of the process to occasionally admit that the problem is random, and everything works fine now.  Sometimes, it is necessary to realize that a problem is outside of your current knowledge, and admit temporary defeat: You can, at least, narrow down the source of the problem by looking logically at all of the possible solutions. By doing this, you can satisfy your curiosity and learn more about what the actual problem was. For example, in the joke, had you never been exposed to the concept of binary numbers, there is no way you could have known that binary - 10 = decimal - 2, but you could have logically come to the conclusion that 10 must not mean ten in the context of the joke, and at that point you are that much closer to getting the joke and at least won't feel so ignorant.

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• WPF: Setting DataContext of a UserControl with Binding not working in XAML

  - by Grant Crofton

  Hi, I'm trying to get my first WPF app working using MVVM, and I've hit a little binding problem. The setup is that I have a view & viewModel which holds User details (the parent), and to try and keep things simple I've put a section of that view into a separate view & viewModel (the child). The child view is defined as a UserControl. The issue I'm having is how to set the DataContext of the child view (the UserControl). My parent ViewModel has a property which exposes the child ViewModel, like so: class ParentViewModel: INotifyPropertyChanged { public ChildViewModel childViewModel { get; set; } //... } In the XAML for my parent view (which has it's DataContext set to the ParentViewModel), I try to set the DataContext of the child view as follows: <views:ChildView x:Name="ChildView" DataContext="{Binding childViewModel}"/> However, this doesn't work. The DataContext of the child view is set to the same DataContext as the parent view (i.e. the ParentViewModel), as if I wasn't setting it at all. I also tried setting the DataContext in the child view itself, which also doesn't work: <UserControl x:Class="DietRecorder.Client.View.ChildView" DataContext="childViewModel" I have found a couple of ways around this. In the child view, I can bind everything by including the ChildViewModel in the path: <SomeControl Visibility="{Binding Path=childViewModel.IsVisible}"> but I don't want the child view to have this level of awareness of the hierarchy. Setting the DataContext in code also works - however, I have to do this after showing the parent view, otherwise the DataContext just gets overwritten when I call Show(): parentView.Show(); parentView.ChildView.DataContext = parentViewModel.childViewModel; This code also makes me feel uneasy, what with the LOD violation and all. It's just the DataContext that seems to be the problem - I can bind other things in the child, for example I tried binding the FontSize to an int property just to test it: <views:ChildView x:Name="ChildView" FontSize="{Binding Path=someVal}"/> And that works fine. But I'm sure binding the DataContext should work - I've seen similar examples of this kind of thing. Have I missed something obvious here? Is there a reason this won't work? Is there a spelling mistake somewhere? (I renamed things for your benefit so you won't be able to help me there anyway). Any thoughts welcome. Thanks, Grant

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• Runtime unhandled exception while executing facedetect.py in opencv

  - by Rupesh Chavan

  When i tried to execute facedetect.py python script from opencv sample example i got the following runtime exception. Can someone please give me some pointer or some clue about the exception and why it is encountering? Here is the stack trace : 'python.exe': Loaded 'C:\Python26\python.exe' 'python.exe': Loaded 'C:\WINDOWS\system32\ntdll.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\kernel32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\python26.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\user32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\gdi32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\advapi32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\rpcrt4.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\shell32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\msvcrt.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\shlwapi.dll' 'python.exe': Loaded 'C:\WINDOWS\WinSxS \x86_Microsoft.VC90.CRT_1fc8b3b9a1e18e3b_9.0.30729.1_x-ww_6f74963e\msvcr90.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\imm32.dll' 'python.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.2982_x-ww_ac3f9c03\comctl32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\comctl32.dll' 'python.exe': Loaded 'C:\Python26\Lib\site-packages\opencv_cv.pyd', Binary was not built with debug information. 'python.exe': Loaded 'C:\OpenCV2.0\bin\libcv200.dll', Binary was not built with debug information. 'python.exe': Loaded 'C:\OpenCV2.0\bin\libcxcore200.dll', Binary was not built with debug information. 'python.exe': Loaded 'C:\Python26\Lib\site-packages\opencv_ml.pyd', Binary was not built with debug information. 'python.exe': Loaded 'C:\OpenCV2.0\bin\libml200.dll', Binary was not built with debug information. 'python.exe': Loaded 'C:\Python26\Lib\site-packages\opencv_highgui.pyd', Binary was not built with debug information. 'python.exe': Loaded 'C:\OpenCV2.0\bin\libhighgui200.dll', Binary was not built with debug information. 'python.exe': Loaded 'C:\WINDOWS\system32\ole32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\oleaut32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\avicap32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\winmm.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\version.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\msvfw32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\avifil32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\msacm32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\msctf.dll' 'python.exe': Loaded 'C:\OpenCV2.0\bin\libopencv_ffmpeg200.dll', Binary was not built with debug information. 'python.exe': Loaded 'C:\WINDOWS\system32\wsock32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\ws2_32.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\ws2help.dll' 'python.exe': Loaded 'C:\WINDOWS\system32\MSCTFIME.IME' Unhandled exception at 0x00e7e4e4 in python.exe: 0xC0000005: Access violation reading location 0xffffffff. Thanks a lot in advance, Rupesh Chavan

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• JBoss 6 deployment of message-driven bean error

  - by AntonioP

  Hello, I have an java EE application which has one message-driven bean and it runs fine on JBoss 4, however when I configure the project for JBoss 6 and deploy on it, I get this error; WARN [org.jboss.ejb.deployers.EjbDeployer.verifier] EJB spec violation: ... The message driven bean must declare one onMessage() method. ... org.jboss.deployers.spi.DeploymentException: Verification of Enterprise Beans failed, see above for error messages. But my bean HAS the onMessage method! It would not have worked on jboss 4 either then. Why do I get this error!? Edit: The class in question looks like this package ... imports ... public class MyMDB implements MessageDrivenBean, MessageListener { AnotherSessionBean a; OneMoreSessionBean b; public MyMDB() {} public void onMessage(Message message) { if (message instanceof TextMessage) { try { //Lookup sessionBeans by jndi, create them lookupABean(); // check message-type, then invokie a.handle(message); // else b.handle(message); } catch (SomeException e) { //handling it } } } public void lookupABean() { try { // code to lookup session beans and create. } catch (CreateException e) { // handling it and catching NamingException too } } } Edit 2: And this is the jboss.xml relevant parts <message-driven> <ejb-name>MyMDB</ejb-name> <destination-jndi-name>topic/A_Topic</destination-jndi-name> <local-jndi-name>A_Topic</local-jndi-name> <mdb-user>user</mdb-user> <mdb-passwd>pass</mdb-passwd> <mdb-client-id>MyMessageBean</mdb-client-id> <mdb-subscription-id>subid</mdb-subscription-id> <resource-ref> <res-ref-name>jms/TopicFactory</res-ref-name> <jndi-name>jms/TopicFactory</jndi-name> </resource-ref> </message-driven>

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• Question About Example In Robert C Martin's _Clean Code_

  - by Jonah

  This is a question about the concept of a function doing only one thing. It won't make sense without some relevant passages for context, so I'll quote them here. They appear on pgs 37-38: To say this differently, we want to be able to read the program as though it were a set of TO paragraphs, each of which is describing the current level of abstraction and referencing subsequent TO paragraphs at the next level down. To include the setups and teardowns, we include setups, then we include the test page content, and then we include the teardowns. To include the setups, we include the suite setup if this is a suite, then we include the regular setup. It turns out to be very dif?cult for programmers to learn to follow this rule and write functions that stay at a single level of abstraction. But learning this trick is also very important. It is the key to keeping functions short and making sure they do “one thing.” Making the code read like a top-down set of TO paragraphs is an effective technique for keeping the abstraction level consistent. He then gives the following example of poor code: public Money calculatePay(Employee e) throws InvalidEmployeeType { switch (e.type) { case COMMISSIONED: return calculateCommissionedPay(e); case HOURLY: return calculateHourlyPay(e); case SALARIED: return calculateSalariedPay(e); default: throw new InvalidEmployeeType(e.type); } } and explains the problems with it as follows: There are several problems with this function. First, it’s large, and when new employee types are added, it will grow. Second, it very clearly does more than one thing. Third, it violates the Single Responsibility Principle7 (SRP) because there is more than one reason for it to change. Fourth, it violates the Open Closed Principle8 (OCP) because it must change whenever new types are added. Now my questions. To begin, it's clear to me how it violates the OCP, and it's clear to me that this alone makes it poor design. However, I am trying to understand each principle, and it's not clear to me how SRP applies. Specifically, the only reason I can imagine for this method to change is the addition of new employee types. There is only one "axis of change." If details of the calculation needed to change, this would only affect the submethods like "calculateHourlyPay()" Also, while in one sense it is obviously doing 3 things, those three things are all at the same level of abstraction, and can all be put into a TO paragraph no different from the example one: TO calculate pay for an employee, we calculate commissioned pay if the employee is commissioned, hourly pay if he is hourly, etc. So aside from its violation of the OCP, this code seems to conform to Martin's other requirements of clean code, even though he's arguing it does not. Can someone please explain what I am missing? Thanks.

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• ASP.NET MVC ViewModel Pattern

  - by Omu

  EDIT: I made something much better to fill and read data from a view using ViewModels, called it ValueInjecter. http://valueinjecter.codeplex.com/documentation using the ViewModel to store the mapping logic was not such a good idea because there was repetition and SRP violation, but now with the ValueInjecter I have clean ViewModels and dry mapping code I made a ViewModel pattern for editing stuff in asp.net mvc this pattern is usefull when you have to make a form for editing an entity and you have to put on the form some dropdowns for the user to choose some values public class OrganisationViewModel { //paramterless constructor required, cuz we are gonna get an OrganisationViewModel object from the form in the post save method public OrganisationViewModel() : this(new Organisation()) {} public OrganisationViewModel(Organisation o) { Organisation = o; Country = new SelectList(LookupFacade.Country.GetAll(), "ID", "Description", CountryKey); } //that's the Type for whom i create the viewmodel public Organisation Organisation { get; set; } #region DropDowns //for each dropdown i have a int? Key that stores the selected value public IEnumerable<SelectListItem> Country { get; set; } public int? CountryKey { get { if (Organisation.Country != null) { return Organisation.Country.ID; } return null; } set { if (value.HasValue) { Organisation.Country = LookupFacade.Country.Get(value.Value); } } } #endregion } and that's how i use it public ViewResult Edit(int id) { var model = new OrganisationViewModel(organisationRepository.Get(id)); return View(model); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(OrganisationViewModel model) { organisationRepository.SaveOrUpdate(model.Organisation); return RedirectToAction("Index"); } and the markup <p> <label for="Name"> Name:</label> <%= Html.Hidden("Organisation.ID", Model.Organisation.ID)%> <%= Html.TextBox("Organisation.Name", Model.Organisation.Name)%> <%= Html.ValidationMessage("Organisation.Name", "*")%> </p> <p> ... <label for="CountryKey"> Country:</label> <%= Html.DropDownList("CountryKey", Model.Country, "please select") %> <%= Html.ValidationMessage("CountryKey", "*") %> </p> so tell me what you think about it

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• AccessViolationException thrown

  - by user255371

  Hi, I’m working on a project that’s written in C# and uses a C++ dll to communicate with a robot. Originally the software was written in C# VS 2003 and was converted to VS 2008 (no change to the code) using .Net 2.0. Now, I started seeing the “Attempted to read or write protected memory…” on some computers. The Access violation error is always thrown when the code calls a particular method from the dll, however, that very same method is called over and over throughout the task and executes fine, just sometimes it throws the error. Also, the robot seems to execute the command fine which tells me that the values passed into the dll exist and thus are accessible. The software with the .Net 1.1 has been used for years and worked fine without ever throwing any memory errors. Now that it has been using .Net 2.0 it throws errors on some computers only. I’m not sure what’s causing the issue. I ruled out inappropriate calling (incorrect marshalling …) of the dll methods as it has been working fine with .Net 1.1 for years and thus should work fine in .Net 2.0 as well. I’ve seen some posts suggesting that it could be the GC, but then again why would it only happen on this one computer and only sometimes. Also, the values passed in are all global variables in the C# code and thus they should exist until the application is shut down and GC has no business moving any of those around or deleting them. Another observation, as I mentioned above, the robot executes the command normally which means that it gets all its necessary values. Not sure what the C++ dll’s method would do at the end where the GC could mess up stuff. It shouldn’t try to delete the global variables passed in and the method is not modifying those variables either (I’m not expecting any return values through the passed in values, the only return value is the method return which again shouldn’t have anything to do with GC.) One important piece of information I should add is that I have no access to the C++ code and thus cannot make any changes there. The fix has to come through the C# code or some settings on the computer or something else that I am in control of. Any help greatly appreciated. Thanks. Code snippet: Original method call in VS 2003 [DllImport("TOOLB32.dll",EntryPoint="TbxMoveWash")] public static extern int TbxMoveWash(int tArmId, string lpszCarrierRackId, int eZSelect, int[] lpTipSet, int tVol, bool bFastW); which I modified after seeing the error to the following (but the error still occurs): [DllImport("TOOLB32.dll",EntryPoint="TbxMoveWash")] public static extern int TbxMoveWash(int tArmId, string lpszCarrierRackId, int eZSelect, [MarshalAs(UnmanagedType.LPArray, SizeConst = 8)] int[] lpTipSet, int tVol, bool bFastW);

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• Why does Celery work in Python shell, but not in my Django views? (import problem)

  - by TIMEX

  I installed Celery (latest stable version.) I have a directory called /home/myuser/fable/jobs. Inside this directory, I have a file called tasks.py: from celery.decorators import task from celery.task import Task class Submitter(Task): def run(self, post, **kwargs): return "Yes, it works!!!!!!" Inside this directory, I also have a file called celeryconfig.py: BROKER_HOST = "localhost" BROKER_PORT = 5672 BROKER_USER = "abc" BROKER_PASSWORD = "xyz" BROKER_VHOST = "fablemq" CELERY_RESULT_BACKEND = "amqp" CELERY_IMPORTS = ("tasks", ) In my /etc/profile, I have these set as my PYTHONPATH: PYTHONPATH=/home/myuser/fable:/home/myuser/fable/jobs So I run my Celery worker using the console ($ celeryd --loglevel=INFO), and I try it out. I open the Python console and import the tasks. Then, I run the Submitter. >>> import fable.jobs.tasks as tasks >>> s = tasks.Submitter() >>> s.delay("abc") <AsyncResult: d70d9732-fb07-4cca-82be-d7912124a987> Everything works, as you can see in my console [2011-01-09 17:30:05,766: INFO/MainProcess] Task tasks.Submitter[d70d9732-fb07-4cca-82be-d7912124a987] succeeded in 0.0398268699646s: But when I go into my Django's views.py and run the exact 3 lines of code as above, I get this: [2011-01-09 17:25:20,298: ERROR/MainProcess] Unknown task ignored: "Task of kind 'fable.jobs.tasks.Submitter' is not registered, please make sure it's imported.": {'retries': 0, 'task': 'fable.jobs.tasks.Submitter', 'args': ('abc',), 'expires': None, 'eta': None, 'kwargs': {}, 'id': 'eb5c65b4-f352-45c6-96f1-05d3a5329d53'} Traceback (most recent call last): File "/home/myuser/mysite-env/lib/python2.6/site-packages/celery/worker/listener.py", line 321, in receive_message eventer=self.event_dispatcher) File "/home/myuser/mysite-env/lib/python2.6/site-packages/celery/worker/job.py", line 299, in from_message eta=eta, expires=expires) File "/home/myuser/mysite-env/lib/python2.6/site-packages/celery/worker/job.py", line 243, in __init__ self.task = tasks[self.task_name] File "/home/myuser/mysite-env/lib/python2.6/site-packages/celery/registry.py", line 63, in __getitem__ raise self.NotRegistered(str(exc)) NotRegistered: "Task of kind 'fable.jobs.tasks.Submitter' is not registered, please make sure it's imported." It's weird, because the celeryd client does show that it's registered, when I launch it. [2011-01-09 17:38:27,446: WARNING/MainProcess] Configuration -> . broker -> amqp://GOGOme@localhost:5672/fablemq . queues -> . celery -> exchange:celery (direct) binding:celery . concurrency -> 1 . loader -> celery.loaders.default.Loader . logfile -> [stderr]@INFO . events -> OFF . beat -> OFF . tasks -> . tasks.Decayer . tasks.Submitter Can someone help?

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• What should I do or don't do to avoid Delphi "push dword" bug.

  - by Maksee

  I found that Delphi 5 generates invalid assembly code in specific cases. I can't understand in what cases in general. The example below produces access violation since a very strange optimization occurs. For a byte in a record or array Delphi generates push dword [...], pop ebx, mov .., bl that works correctly if there are data after this byte (we need at least three to push dword correctly), but fails if the data is inaccessible. I emulated the strict boundaries here with win32 Virtual* functions Specifically the error occurs when the last byte from the block accessed inside FeedBytesToClass procedure. And if I try to change something like using data array instead of object property of remove actionFlag variable, Delphi generates correct assembly instructions. const BlockSize = 4096; type TSomeClass = class private fBytes: PByteArray; public property Bytes: PByteArray read fBytes; constructor Create; destructor Destroy;override; end; constructor TSomeClass.Create; begin inherited Create; GetMem(fBytes, BlockSize); end; destructor TSomeClass.Destroy; begin FreeMem(fBytes); inherited; end; procedure FeedBytesToClass(SrcDataBytes: PByteArray; Count: integer); var j: integer; Ofs: integer; actionFlag: boolean; AClass: TSomeClass; begin AClass:=TSomeClass.Create; try actionFlag:=true; for j:=0 to Count-1 do begin Ofs:=j; if actionFlag then begin AClass.Bytes[Ofs]:=SrcDataBytes[j]; end; end; finally AClass.Free; end; end; procedure TForm31.Button1Click(Sender: TObject); var SrcDataBytes: PByteArray; begin SrcDataBytes:=VirtualAlloc(Nil, BlockSize, MEM_COMMIT, PAGE_READWRITE); try if VirtualLock(SrcDataBytes, BlockSize) then try FeedBytesToClass(SrcDataBytes, BlockSize); finally VirtualUnLock(SrcDataBytes, BlockSize); end; finally VirtualFree(SrcDataBytes, MEM_DECOMMIT, BlockSize); end; end; Initially the error occured when I used access to RGB data of bitmap bits, but the code there is too complex so I narrowed it to this fragment. So the question is what is here so specific that makes Delphi produce push,pop,mov optimization. I need to know this in order to avoid such side effects in general.

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• Return pre-UPDATE column values in PostgreSQL without using triggers, functions or other "magic"

  - by Python Larry

  I have a related question, but this is another part of MY puzzle. I would like to get the OLD VALUE of a Column from a Row that was UPDATEd... WITHOUT using Triggers (nor Stored Procedures, nor any other extra, non-SQL/-query entities). The query I have is like this: UPDATE my_table SET processing_by = our_id_info -- unique to this instance WHERE trans_nbr IN ( SELECT trans_nbr FROM my_table GROUP BY trans_nbr HAVING COUNT(trans_nbr) > 1 LIMIT our_limit_to_have_single_process_grab ) RETURNING row_id If I could do "FOR UPDATE ON my_table" at the end of the subquery, that'd be devine (and fix my other question/problem). But, that won't work: can't have this AND a "GROUP BY" (which is necessary for figuring out the COUNT of trans_nbr's). Then I could just take those trans_nbr's and do a query first to get the (soon-to-be-) former processing_by values. I've tried doing like: UPDATE my_table SET processing_by = our_id_info -- unique to this instance FROM my_table old_my_table JOIN ( SELECT trans_nbr FROM my_table GROUP BY trans_nbr HAVING COUNT(trans_nbr) > 1 LIMIT our_limit_to_have_single_process_grab ) sub_my_table ON old_my_table.trans_nbr = sub_my_table.trans_nbr WHERE my_table.trans_nbr = sub_my_table.trans_nbr AND my_table.processing_by = old_my_table.processing_by RETURNING my_table.row_id, my_table.processing_by, old_my_table.processing_by But that can't work; "old_my_table" is not viewable outside of the join; the RETURNING clause is blind to it. I've long since lost count of all the attempts I've made; I have been researching this for literally hours. If I could just find a bullet-proof way to lock the rows in my subquery - and ONLY those rows, and WHEN the subquery happens - all the concurrency issues I'm trying to avoid disappear... UPDATE: [WIPES EGG OFF FACE] Okay, so I had a typo in the non-generic code of the above that I wrote "doesn't work"; it does... thanks to Erwin Brandstetter, below, who stated it would, I re-did it (after a night's sleep, refreshed eyes, and a banana for bfast). Since it took me so long/hard to find this sort of solution, perhaps my embarrassment is worth it? At least this is on SO for posterity now... : What I now have (that works) is like this: UPDATE my_table SET processing_by = our_id_info -- unique to this instance FROM my_table AS old_my_table WHERE trans_nbr IN ( SELECT trans_nbr FROM my_table GROUP BY trans_nbr HAVING COUNT(*) > 1 LIMIT our_limit_to_have_single_process_grab ) AND my_table.row_id = old_my_table.row_id RETURNING my_table.row_id, my_table.processing_by, old_my_table.processing_by AS old_processing_by The COUNT(*) is per a suggestion from Flimzy in a comment on my other (linked above) question. (I was more specific than necessary. [In this instance.])

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• _heapwalk reports _HEAPBADNODE, causes breakpoint or loops endlessly

  - by Stefan Hubert

  I use _heapwalk to gather statistics about the Process' standard heap. Under certain circumstances i observe unexpected behaviours like: _HEAPBADNODE is returned some breakpoint is triggered inside _heapwalk, telling me the heap might got corrupted access violation inside _heapWalk. I saw different behaviours on different Computers. On one Windows XP 32 bit machine everything looked fine, whereas on two Windows XP 64 bit machines i saw the mentioned symptoms. I saw this behaviour only if LowFragmentationHeap was enabled. I played around a bit. I walked the heap several times right one after another inside my program. First time doing nothing in between the subsequent calls to _heapWalk (everything fine). Then again, this time doing some stuff (for gathering statistics) in between two subsequent calls to _heapWalk. Depending upon what I did there, I sometimes got the described symptoms. Here finally a question: What exactly is safe and what is not safe to do in between two subsequent calls to _heapWalk during a complete heap walk run? Naturally, i shall not manipulate the heap. Therefore i doublechecked that i don't call new and delete. However, my observation is that function calls with some parameter passing causes my heap walk run to fail already. I subsequently added function calls and increasing number of parameters passed to these. My feeling was two function calls with two paramters being passed did not work anymore. However I would like to know why. Any ideas why this does not happen on some machines? Any ideas why this only happens if LowFragmentationHeap is enabled? Sample Code finally: #include <malloc.h> void staticMethodB( int a, int b ) { } void staticMethodA( int a, int b, int c) { staticMethodB( 3, 6); return; } ... _HEAPINFO hinfo; hinfo._pentry = NULL; while( ( heapstatus = _heapwalk( &hinfo ) ) == _HEAPOK ) { //doing nothing here works fine //however if i call functions here with parameters, this causes //_HEAPBADNODE or something else staticMethodA( 3,4,5); } switch( heapstatus ) { ... case _HEAPBADNODE: assert( false ); /*ERROR - bad node in heap */ break; ...

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• Adding a generic image field onto a ModelForm in django

  - by Prairiedogg

  I have two models, Room and Image. Image is a generic model that can tack onto any other model. I want to give users a form to upload an image when they post information about a room. I've written code that works, but I'm afraid I've done it the hard way, and specifically in a way that violates DRY. Was hoping someone who's a little more familiar with django forms could point out where I've gone wrong. Update: I've tried to clarify why I chose this design in comments to the current answers. To summarize: I didn't simply put an ImageField on the Room model because I wanted more than one image associated with the Room model. I chose a generic Image model because I wanted to add images to several different models. The alternatives I considered were were multiple foreign keys on a single Image class, which seemed messy, or multiple Image classes, which I thought would clutter my schema. I didn't make this clear in my first post, so sorry about that. Seeing as none of the answers so far has addressed how to make this a little more DRY I did come up with my own solution which was to add the upload path as a class attribute on the image model and reference that every time it's needed. # Models class Image(models.Model): content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') image = models.ImageField(_('Image'), height_field='', width_field='', upload_to='uploads/images', max_length=200) class Room(models.Model): name = models.CharField(max_length=50) image_set = generic.GenericRelation('Image') # The form class AddRoomForm(forms.ModelForm): image_1 = forms.ImageField() class Meta: model = Room # The view def handle_uploaded_file(f): # DRY violation, I've already specified the upload path in the image model upload_suffix = join('uploads/images', f.name) upload_path = join(settings.MEDIA_ROOT, upload_suffix) destination = open(upload_path, 'wb+') for chunk in f.chunks(): destination.write(chunk) destination.close() return upload_suffix def add_room(request, apartment_id, form_class=AddRoomForm, template='apartments/add_room.html'): apartment = Apartment.objects.get(id=apartment_id) if request.method == 'POST': form = form_class(request.POST, request.FILES) if form.is_valid(): room = form.save() image_1 = form.cleaned_data['image_1'] # Instead of writing a special function to handle the image, # shouldn't I just be able to pass it straight into Image.objects.create # ...but it doesn't seem to work for some reason, wrong syntax perhaps? upload_path = handle_uploaded_file(image_1) image = Image.objects.create(content_object=room, image=upload_path) return HttpResponseRedirect(room.get_absolute_url()) else: form = form_class() context = {'form': form, } return direct_to_template(request, template, extra_context=context)

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• Boggling Direct3D9 dynamic vertex buffer Lock crash/post-lock failure on Intel GMA X3100.

  - by nj

  Hi, For starters I'm a fairly seasoned graphics programmer but as wel all know, everyone makes mistakes. Unfortunately the codebase is a bit too large to start throwing sensible snippets here and re-creating the whole situation in an isolated CPP/codebase is too tall an order -- for which I am sorry, do not have the time. I'll do my best to explain. B.t.w, I will of course supply specific pieces of code if someone wonders how I'm handling this-or-that! As with all resources in the D3DPOOL_DEFAULT pool, when the device context is taken away from you you'll sooner or later will have to reset your resources. I've built a mechanism to handle this for all relevant resources that's been working for years; but that fact nothingwithstanding I've of course checked, asserted and doubted any assumption since this bug came to light. What happens is as follows: I have a rather large dynamic vertex buffer, exact size 18874368 bytes. This buffer is locked (and discarded fully using the D3DLOCK_DISCARD flag) each frame prior to generating dynamic geometry (isosurface-related, f.y.i) to it. This works fine, until, of course, I start to reset. It might take 1 time, it might take 2 or it might take 5 resets to set off a bug that causes an access violation either on the pointer returned by the Lock() operation on the renewed resource or a plain crash -- regarding a somewhat similar address, but without the offset that it has tacked on to it in the first case because in that case we're somewhere halfway writing -- iside the D3D9 dll Lock() call. I've tested this on other hardware, upgraded my GMA X3100 drivers (using a MacBook with BootCamp) to the latest ones, but I can't reproduce it on any other machine and I'm at a loss about what's wrong here. I have tried to reproduce a similar situation with a similar buffer (I've got a large scratch pad of the same type I filled with quads) and beyond a certain amount of bytes it started to behave likewise. I'm not asking for a solution here but I'm very interested if there are other developers here who have battled with the same foe or maybe some who can point me in some insightful direction, maybe ask some questions that might shed a light on what I may or may not be overlooking. Another interesting artifact is that the vertex buffer starts to bug if I supply both D3DLOCK_DISCARD and D3DLOCK_NOOVERWRITE together which, even though not very logical (you're not going to overwrite if you've just discarded all), gives graphics glitches. Thanks and any corrections are more than welcome. Niels p.s - A friend of mine raised the valid point that it is a huge buffer for onboard video RAM and it's being at least double or triple buffered internally due to it's dynamic nature. On the other hand, the debug output (D3D9 debug DLL + max. warning output) remains silent. p.s 2 - Had it tested on more machines and still works -- it's probably a matter of circumstance: the huge dynamic, internally double/trippled buffered buffer, not a lot of memory and drivers that don't complain when they should.. Unless someone has a better suggestion; I'd still love to hear it :)

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• Error while Trying to Hook "TerminateProcess" Function. Target Process crashes. Can anyone help me

  - by desaiparth

  Debugging with visual studio 2005 The following Error Displayed :Unhandled exception at 0x00000000 in procexp.exe: 0xC0000005: Access violation reading location 0x00000000. And Thread Information: 2704 Win32 Thread 00000000 Normal 0 extern "C" VDLL2_API BOOL WINAPI MyTerminateProcess(HANDLE hProcess,UINT uExitCode) { SetLastError(5); return FALSE; } FARPROC HookFunction(char *UserDll,FARPROC pfn,FARPROC HookFunc) { DWORD dwSizeofExportTable=0; DWORD dwRelativeVirtualAddress=0; HMODULE hm=GetModuleHandle(NULL); FARPROC pfnOriginalAddressToReturn; PIMAGE_DOS_HEADER pim=(PIMAGE_DOS_HEADER)hm; PIMAGE_NT_HEADERS pimnt=(PIMAGE_NT_HEADERS)((DWORD)pim + (DWORD)pim-e_lfanew); PIMAGE_DATA_DIRECTORY pimdata=(PIMAGE_DATA_DIRECTORY)&(pimnt-OptionalHeader.DataDirectory); PIMAGE_OPTIONAL_HEADER pot=&(pimnt-OptionalHeader); PIMAGE_DATA_DIRECTORY pim2=(PIMAGE_DATA_DIRECTORY)((DWORD)pot+(DWORD)104); dwSizeofExportTable=pim2-Size; dwRelativeVirtualAddress=pim2-VirtualAddress; char *ascstr; PIMAGE_IMPORT_DESCRIPTOR pimexp=(PIMAGE_IMPORT_DESCRIPTOR)(pim2-VirtualAddress + (DWORD)pim); while(pimexp-Name) { ascstr=(char *)((DWORD)pim + (DWORD)pimexp-Name); if(strcmpi(ascstr,UserDll) == 0) { break; } pimexp++; } PIMAGE_THUNK_DATA pname=(PIMAGE_THUNK_DATA)((DWORD)pim+(DWORD)pimexp-FirstThunk); LPDWORD lpdw=&(pname-u1.Function); DWORD dwError=0; DWORD OldProtect=0; while(pname-u1.Function) { if((DWORD)pname-u1.Function == (DWORD)pfn) { lpdw=&(pname-u1.Function); VirtualProtect((LPVOID)lpdw,sizeof(DWORD),PAGE_READWRITE,&OldProtect); pname-u1.Function=(DWORD)HookFunc; VirtualProtect((LPVOID)lpdw,sizeof(DWORD),PAGE_READONLY,&OldProtect); return pfn; } pname++; } return (FARPROC)0; } FARPROC CallHook(void) { HMODULE hm=GetModuleHandle(TEXT("Kernel32.dll")); FARPROC fp=GetProcAddress(hm,"TerminateProcess"); HMODULE hm2=GetModuleHandle(TEXT("vdll2.dll")); FARPROC fpHook=GetProcAddress(hm2,"MyTerminateProcess"); dwAddOfTerminateProcess=HookFunction("Kernel32.dll",fp,fpHook); if(dwAddOfTerminateProcess == 0) { MessageBox(NULL,TEXT("Unable TO Hook Function."),TEXT("Parth"),MB_OK); } else { MessageBox(NULL,TEXT("Success Hooked."),TEXT("Parth"),MB_OK); } return 0; } Thanks in advance for any help.

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• derby + hibernate ConstraintViolationException using manytomany relationships

  - by user364470

  Hi, I'm new to Hibernate+Derby... I've seen this issue mentioned throughout the google, but have not seen a proper resolution. This following code works fine with mysql, but when I try this on derby i get exceptions: ( each Tag has two sets of files and vise-versa - manytomany) Tags.java @Entity @Table(name="TAGS") public class Tags implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) public long getId() { return id; } @ManyToMany(targetEntity=Files.class ) @ForeignKey(name="USER_TAGS_FILES",inverseName="USER_FILES_TAGS") @JoinTable(name="USERTAGS_FILES", joinColumns=@JoinColumn(name="TAGS_ID"), inverseJoinColumns=@JoinColumn(name="FILES_ID")) public Set<data.Files> getUserFiles() { return userFiles; } @ManyToMany(mappedBy="autoTags", targetEntity=data.Files.class) public Set<data.Files> getAutoFiles() { return autoFiles; } Files.java @Entity @Table(name="FILES") public class Files implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) public long getId() { return id; } @ManyToMany(mappedBy="userFiles", targetEntity=data.Tags.class) public Set getUserTags() { return userTags; } @ManyToMany(targetEntity=Tags.class ) @ForeignKey(name="AUTO_FILES_TAGS",inverseName="AUTO_TAGS_FILES") @JoinTable(name="AUTOTAGS_FILES", joinColumns=@JoinColumn(name="FILES_ID"), inverseJoinColumns=@JoinColumn(name="TAGS_ID")) public Set getAutoTags() { return autoTags; } I add some data to the DB, but when running over Derby these exception turn up (the don't using mysql) Exceptions SEVERE: DELETE on table 'FILES' caused a violation of foreign key constraint 'USER_FILES_TAGS' for key (3). The statement has been rolled back. Jun 10, 2010 9:49:52 AM org.hibernate.event.def.AbstractFlushingEventListener performExecutions SEVERE: Could not synchronize database state with session org.hibernate.exception.ConstraintViolationException: could not delete: [data.Files#3] at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:2712) at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:2895) at org.hibernate.action.EntityDeleteAction.execute(EntityDeleteAction.java:97) at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:268) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:260) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:184) at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321) at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51) at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1206) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:613) at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344) at $Proxy13.flush(Unknown Source) at data.HibernateORM.removeFile(HibernateORM.java:285) at data.DataImp.removeFile(DataImp.java:195) at booting.DemoBootForTestUntilTestClassesExist.main(DemoBootForTestUntilTestClassesExist.java:62) I have never used derby before so maybe there is something crutal that i'm missing 1) what am I doing wrong? 2) is there any way of cascading properly when I have 2 many-to-many relationships between two classes? Thanks!

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• How do access a secure website within a sharepoint webpart?

  - by Bill

  How do access a secure website within a sharepoint webpart? The following code works fine as a console application but if you run it in a webpart, you will get a access violation WebRequest request = WebRequest.Create("https://somesecuresite.com"); WebResponse firstResponse = null; try { firstResponse = request.GetResponse(); } catch (WebException ex) { writer.WriteLine("Error: " + ex.ToString()); return; } if you access a non secure site, it also works. Any ideas? Error: System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a receive. --- System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. at System.Net.UnsafeNclNativeMethods.NativePKI.CertVerifyCertificateChainPolicy(IntPtr policy, SafeFreeCertChain chainContext, ChainPolicyParameter& cpp, ChainPolicyStatus& ps) at System.Net.PolicyWrapper.VerifyChainPolicy(SafeFreeCertChain chainContext, ChainPolicyParameter& cpp) at System.Net.Security.SecureChannel.VerifyRemoteCertificate(RemoteCertValidationCallback remoteCertValidationCallback) at System.Net.Security.SslState.CompleteHandshake() at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult) at System.Net.TlsStream.CallProcessAuthentication(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result) at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size) at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size) at System.Net.ConnectStream.WriteHeaders(Boolean async) --- End of inner exception stack trace --- at System.Net.HttpWebRequest.GetResponse()

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• CoGetClassObject gives many First-chance exceptions in ATL project. Should I worry?

  - by Andrew

  Hello, I have written a COM object that in turn uses a thrid party ActiveX control. In my FinalConstruct() for my COM object, I instantiate the ActiveX control with the follow code: HRESULT hRes; LPCLASSFACTORY2 pClassFactory; hRes = CoInitializeEx(NULL,COINIT_APARTMENTTHREADED); bool bTest = SUCCEEDED(hRes); if (!bTest) return E_FAIL; if (SUCCEEDED(CoGetClassObject(__uuidof(SerialPortSniffer), CLSCTX_INPROC_SERVER, NULL, IID_IClassFactory2, (LPVOID *)(&pClassFactory)))) { ... more set up code When I step over the line if (SUCCEEDED(CoGetClassObject(__uuidof(SerialPortSniffer), ..., I get 20+ lines in the Output window stating: First-chance exception at 0x0523f82e in SillyComDriver.exe: 0xC0000005: Access violation writing location 0x00000000. I also get the lines: First-chance exception at 0x051e3f3d in SillyComDriver.exe: 0xC0000096: Privileged instruction. First-chance exception at 0x100ab9e6 in SillyComDriver.exe: 0xC000001D: Illegal Instruction. Notice these are first-chance exceptions. The program runs as expected I can access the third party methods/properties. Still, I'm left wondering why they are occurring. Perhaps my way of instantiating the ActiveX control (for which I want use of it's methods/properties and not it's GUI stuff) is incorrect? Besides the code I'm showing, I also put the line import "spsax.dll" no_namespace in the stdafx.h That's all the code necessary for my simple demo project. I noticed this problem because I had (inadvertently) set the "break on exceptions" options in my "real" project and it was breaking on this line. Once I removed it, it also works. If you're read this far thank you, and perhaps I can ask one other minor question. In my demo project, if I right click on SerialPortSniffer and "go to definition", it takes me to the file C:....\AppData\Local\Temp\spsax.tlh. Can someone explain that? Finally, in my "real" project, right clicking on SerialPortSniffer and going to difinition leads to "The symbol 'SerialPortSniffer' is not defined". It doesn't seem to affect the program though. Is there some setting I've messed up? By the way, all my code is written w/ VS2008. Thanks, Dave

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• Issue accessing remote Infinispan mbeans

  - by user1960172

  I am able to access the Mbeans by local Jconsole but not able to access the MBEANS from a remote Host. My COnfiguration: <?xml version='1.0' encoding='UTF-8'?> <server xmlns="urn:jboss:domain:1.4"> <extensions> <extension module="org.infinispan.server.endpoint"/> <extension module="org.jboss.as.clustering.infinispan"/> <extension module="org.jboss.as.clustering.jgroups"/> <extension module="org.jboss.as.connector"/> <extension module="org.jboss.as.jdr"/> <extension module="org.jboss.as.jmx"/> <extension module="org.jboss.as.logging"/> <extension module="org.jboss.as.modcluster"/> <extension module="org.jboss.as.naming"/> <extension module="org.jboss.as.remoting"/> <extension module="org.jboss.as.security"/> <extension module="org.jboss.as.threads"/> <extension module="org.jboss.as.transactions"/> <extension module="org.jboss.as.web"/> </extensions> <management> <security-realms> <security-realm name="ManagementRealm"> <authentication> <local default-user="$local"/> <properties path="mgmt-users.properties" relative-to="jboss.server.config.dir"/> </authentication> </security-realm> <security-realm name="ApplicationRealm"> <authentication> <local default-user="$local" allowed-users="*"/> <properties path="application-users.properties" relative-to="jboss.server.config.dir"/> </authentication> </security-realm> </security-realms> <management-interfaces> <native-interface security-realm="ManagementRealm"> <socket-binding native="management-native"/> </native-interface> <http-interface security-realm="ManagementRealm"> <socket-binding http="management-http"/> </http-interface> </management-interfaces> </management> <profile> <subsystem xmlns="urn:jboss:domain:logging:1.2"> <console-handler name="CONSOLE"> <level name="INFO"/> <formatter> <pattern-formatter pattern="%K{level}%d{HH:mm:ss,SSS} %-5p [%c] (%t) %s%E%n"/> </formatter> </console-handler> <periodic-rotating-file-handler name="FILE" autoflush="true"> <formatter> <pattern-formatter pattern="%d{HH:mm:ss,SSS} %-5p [%c] (%t) %s%E%n"/> </formatter> <file relative-to="jboss.server.log.dir" path="server.log"/> <suffix value=".yyyy-MM-dd"/> <append value="true"/> </periodic-rotating-file-handler> <logger category="com.arjuna"> <level name="WARN"/> </logger> <logger category="org.apache.tomcat.util.modeler"> <level name="WARN"/> </logger> <logger category="org.jboss.as.config"> <level name="DEBUG"/> </logger> <logger category="sun.rmi"> <level name="WARN"/> </logger> <logger category="jacorb"> <level name="WARN"/> </logger> <logger category="jacorb.config"> <level name="ERROR"/> </logger> <root-logger> <level name="INFO"/> <handlers> <handler name="CONSOLE"/> <handler name="FILE"/> </handlers> </root-logger> </subsystem> <subsystem xmlns="urn:infinispan:server:endpoint:6.0"> <hotrod-connector socket-binding="hotrod" cache-container="clustered"> <topology-state-transfer lazy-retrieval="false" lock-timeout="1000" replication-timeout="5000"/> </hotrod-connector> <memcached-connector socket-binding="memcached" cache-container="clustered"/> <!--<rest-connector virtual-server="default-host" cache-container="clustered" security-domain="other" auth-method="BASIC"/> --> <rest-connector virtual-server="default-host" cache-container="clustered" /> <websocket-connector socket-binding="websocket" cache-container="clustered"/> </subsystem> <subsystem xmlns="urn:jboss:domain:datasources:1.1"> <datasources/> </subsystem> <subsystem xmlns="urn:infinispan:server:core:5.3" default-cache-container="clustered"> <cache-container name="clustered" default-cache="default"> <transport executor="infinispan-transport" lock-timeout="60000"/> <distributed-cache name="default" mode="SYNC" segments="20" owners="2" remote-timeout="30000" start="EAGER"> <locking isolation="READ_COMMITTED" acquire-timeout="30000" concurrency-level="1000" striping="false"/> <transaction mode="NONE"/> </distributed-cache> <distributed-cache name="memcachedCache" mode="SYNC" segments="20" owners="2" remote-timeout="30000" start="EAGER"> <locking isolation="READ_COMMITTED" acquire-timeout="30000" concurrency-level="1000" striping="false"/> <transaction mode="NONE"/> </distributed-cache> <distributed-cache name="namedCache" mode="SYNC" start="EAGER"/> </cache-container> <cache-container name="security"/> </subsystem> <subsystem xmlns="urn:jboss:domain:jca:1.1"> <archive-validation enabled="true" fail-on-error="true" fail-on-warn="false"/> <bean-validation enabled="true"/> <default-workmanager> <short-running-threads> <core-threads count="50"/> <queue-length count="50"/> <max-threads count="50"/> <keepalive-time time="10" unit="seconds"/> </short-running-threads> <long-running-threads> <core-threads count="50"/> <queue-length count="50"/> <max-threads count="50"/> <keepalive-time time="10" unit="seconds"/> </long-running-threads> </default-workmanager> <cached-connection-manager/> </subsystem> <subsystem xmlns="urn:jboss:domain:jdr:1.0"/> <subsystem xmlns="urn:jboss:domain:jgroups:1.2" default-stack="${jboss.default.jgroups.stack:udp}"> <stack name="udp"> <transport type="UDP" socket-binding="jgroups-udp"/> <protocol type="PING"/> <protocol type="MERGE2"/> <protocol type="FD_SOCK" socket-binding="jgroups-udp-fd"/> <protocol type="FD_ALL"/> <protocol type="pbcast.NAKACK"/> <protocol type="UNICAST2"/> <protocol type="pbcast.STABLE"/> <protocol type="pbcast.GMS"/> <protocol type="UFC"/> <protocol type="MFC"/> <protocol type="FRAG2"/> <protocol type="RSVP"/> </stack> <stack name="tcp"> <transport type="TCP" socket-binding="jgroups-tcp"/> <!--<protocol type="MPING" socket-binding="jgroups-mping"/>--> <protocol type="TCPPING"> <property name="initial_hosts">10.32.50.53[7600],10.32.50.64[7600]</property> </protocol> <protocol type="MERGE2"/> <protocol type="FD_SOCK" socket-binding="jgroups-tcp-fd"/> <protocol type="FD"/> <protocol type="VERIFY_SUSPECT"/> <protocol type="pbcast.NAKACK"> <property name="use_mcast_xmit">false</property> </protocol> <protocol type="UNICAST2"/> <protocol type="pbcast.STABLE"/> <protocol type="pbcast.GMS"/> <protocol type="UFC"/> <protocol type="MFC"/> <protocol type="FRAG2"/> <protocol type="RSVP"/> </stack> </subsystem> <subsystem xmlns="urn:jboss:domain:jmx:1.1"> <show-model value="true"/> <remoting-connector use-management-endpoint="false"/> </subsystem> <subsystem xmlns="urn:jboss:domain:modcluster:1.1"> <mod-cluster-config advertise-socket="modcluster" connector="ajp" excluded-contexts="console"> <dynamic-load-provider> <load-metric type="busyness"/> </dynamic-load-provider> </mod-cluster-config> </subsystem> <subsystem xmlns="urn:jboss:domain:naming:1.2"/> <subsystem xmlns="urn:jboss:domain:remoting:1.1"> <connector name="remoting-connector" socket-binding="remoting" security-realm="ApplicationRealm"/> </subsystem> <subsystem xmlns="urn:jboss:domain:security:1.2"> <security-domains> <security-domain name="other" cache-type="infinispan"> <authentication> <login-module code="Remoting" flag="optional"> <module-option name="password-stacking" value="useFirstPass"/> </login-module> <login-module code="RealmUsersRoles" flag="required"> <module-option name="usersProperties" value="${jboss.server.config.dir}/application-users.properties"/> <module-option name="rolesProperties" value="${jboss.server.config.dir}/application-roles.properties"/> <module-option name="realm" value="ApplicationRealm"/> <module-option name="password-stacking" value="useFirstPass"/> </login-module> </authentication> </security-domain> <security-domain name="jboss-web-policy" cache-type="infinispan"> <authorization> <policy-module code="Delegating" flag="required"/> </authorization> </security-domain> </security-domains> </subsystem> <subsystem xmlns="urn:jboss:domain:threads:1.1"> <thread-factory name="infinispan-factory" group-name="infinispan" priority="5"/> <unbounded-queue-thread-pool name="infinispan-transport"> <max-threads count="25"/> <keepalive-time time="0" unit="milliseconds"/> <thread-factory name="infinispan-factory"/> </unbounded-queue-thread-pool> </subsystem> <subsystem xmlns="urn:jboss:domain:transactions:1.2"> <core-environment> <process-id> <uuid/> </process-id> </core-environment> <recovery-environment socket-binding="txn-recovery-environment" status-socket-binding="txn-status-manager"/> <coordinator-environment default-timeout="300"/> </subsystem> <subsystem xmlns="urn:jboss:domain:web:1.1" default-virtual-server="default-host" native="false"> <connector name="http" protocol="HTTP/1.1" scheme="http" socket-binding="http"/> <connector name="ajp" protocol="AJP/1.3" scheme="http" socket-binding="ajp"/> <virtual-server name="default-host" enable-welcome-root="false"> <alias name="localhost"/> <alias name="example.com"/> </virtual-server> </subsystem> </profile> <interfaces> <interface name="management"> <inet-address value="${jboss.bind.address.management:10.32.222.111}"/> </interface> <interface name="public"> <inet-address value="${jboss.bind.address:10.32.222.111}"/> </interface> </interfaces> <socket-binding-group name="standard-sockets" default-interface="public" port-offset="${jboss.socket.binding.port-offset:0}"> <socket-binding name="management-native" interface="management" port="${jboss.management.native.port:9999}"/> <socket-binding name="management-http" interface="management" port="${jboss.management.http.port:9990}"/> <socket-binding name="management-https" interface="management" port="${jboss.management.https.port:9443}"/> <socket-binding name="ajp" port="8089"/> <socket-binding name="hotrod" port="11222"/> <socket-binding name="http" port="8080"/> <socket-binding name="https" port="8443"/> <socket-binding name="jgroups-mping" port="0" multicast-address="${jboss.default.multicast.address:234.99.54.14}" multicast-port="45700"/> <socket-binding name="jgroups-tcp" port="7600"/> <socket-binding name="jgroups-tcp-fd" port="57600"/> <socket-binding name="jgroups-udp" port="55200" multicast-address="${jboss.default.multicast.address:234.99.54.14}" multicast-port="45688"/> <socket-binding name="jgroups-udp-fd" port="54200"/> <socket-binding name="memcached" port="11211"/> <socket-binding name="modcluster" port="0" multicast-address="224.0.1.115" multicast-port="23364"/> <socket-binding name="remoting" port="4447"/> <socket-binding name="txn-recovery-environment" port="4712"/> <socket-binding name="txn-status-manager" port="4713"/> <socket-binding name="websocket" port="8181"/> </socket-binding-group> </server> Remote Process: service:jmx:remoting-jmx://10.32.222.111:4447 I added user to both management and application realm admin=2a0923285184943425d1f53ddd58ec7a test=2b1be81e1da41d4ea647bd82fc8c2bc9 But when i try to connect its says's: Connection failed: Retry When i use Remote process as:10.32.222.111:4447 on the sever it prompts a warning : 16:29:48,084 ERROR [org.jboss.remoting.remote.connection] (Remoting "djd7w4r1" read-1) JBREM000200: Remote connection failed: java.io.IOException: Received an invali d message length of -2140864253 Also disabled Remote authentication: -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.port=12345 Still not able to connect. Any help will be highly appreciated . Thanks

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• Mysterious constraints problem with SQL Server 2000

  - by Ramon

  Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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• JPA entity design / cannot delete entity

  - by timaschew

  I though its simple what I want, but I cannot find any solution for my problem. I'm using playframework 1.2.3 and it's using Hibernate as JPA. So I think playframework has nothing to do with the problem. I have some classes (I omit the nonrelevant fields) public class User { ... } public class Task { public DataContainer dataContainer; } public class DataContainer { public Session session; public User user; } public class Session { ... } So I have association from Task to DataContainer and from DataContainer to Sesssion and the DataContainer belongs to a User. The DataContainers can have always the same User, but the Session have to be different for each instance. And the DataContainer of a Task have also to be different in each instance. A DataContainer can have a Sesesion or not (it's optinal). I use only unidirectional assoc. It should be sufficient. In other words: Every Task must has one DataContainer. Every DataContainer must has one/the same User and can have one Session. To create a DB schema I use JPA annotations: @Entity public class User extends Model { ... } @Entity public class Task extends Model { @OneToOne(optional = false, cascade = CascadeType.ALL) public DataContainer dataContainer; } @Entity public class DataContainer extends Model { @OneToOne(optional = true, cascade = CascadeType.ALL) public Session session; @ManyToOne(optional = false, cascade = CascadeType.ALL) public User user; } @Entity public class Session extends Model { ... } BTW: Model is a play class and provides the primary id as long type. When I create some for each entity a object and 'connect them', I mean the associations, it works fine. But when I try to delete a Session, I get a constraint violation exception, because a DataContainer still refers to the Session I want to delete. I want that the Session (field) of the DataContainer will be set to null respectively the foreign key (session_id) should be unset in the database. This will be okay, because its optional. I don't know, I think I have multiple problems. Am I using the right annotation @OneToOne ? I found on the internet some additional annotation and attributes: @JoinColumn and a mappedBy attribute for the inverse relationship. But I don't have it, because its not bidirectional. Or is a bidirectional assoc. essentially? Another try was to use @OnDelete(action = OnDeleteAction.CASCADE) the the contraint changed from NO ACTIONs when update or delete to: ADD CONSTRAINT fk4745c17e6a46a56 FOREIGN KEY (session_id) REFERENCES annotation_session (id) MATCH SIMPLE ON UPDATE NO ACTION ON DELETE CASCADE; But in this case, when I delete a session, the DataContainer and User is deleted. That's wrong for me. EDIT: I'm using postgresql 9, the jdbc stuff is included in play, my only db config is db=postgres://app:app@localhost:5432/app

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