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  • Why is it a bad practice to call System.gc?

    - by zneak
    After answering to a question about how to force-free objects in Java (the guy was clearing a 1.5GB HashMap) with System.gc(), I've been told it's a bad practice to call System.gc() manually, but the comments seemed mitigated about it. So much that no one dared to upvote it, nor downvote it. I've been told there it's a bad practice, but then I've also been told garbage collector runs don't systematically stop the world anymore, and that it could also be only seen as a hint, so I'm kind of at loss. I do understand that usually the JVM knows better than you when it needs to reclaim memory. I also understand that worrying about a few kilobytes of data is silly. And I also understand that even megabytes of data isn't what it was a few years back. But still, 1.5 gigabyte? And you know there's like 1.5 GB of data hanging around in memory; it's not like it's a shot in the dark. Is System.gc() systematically bad, or is there some point at which it becomes okay? So the question is actually double: Why is it or not a bad practice to call System.gc()? Is it really a hint under certain implementations, or is it always a full collection cycle? Are there really garbage collector implementations that can do their work without stopping the world? Please shed some light over the various assertions people have made. Where's the threshold? Is it never a good idea to call System.gc(), or are there times when it's acceptable? If any, what are those times?

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  • Practice of checking 'trueness' or 'equality' in conditional statements - does it really make sense?

    - by Senthil
    I remember many years back, when I was in school, one of my computer science teachers taught us that it was better to check for 'trueness' or 'equality' of a condition and not the negative stuff like 'inequality'. Let me elaborate - If a piece of conditional code can be written by checking whether an expression is true or false, we should check the 'trueness'. Example: Finding out whether a number is odd - it can be done in two ways: if ( num % 2 != 0 ) { // Number is odd } or if ( num % 2 == 1 ) { // Number is odd } When I was beginning to code, I knew that num % 2 == 0 implies the number is even, so I just put a ! there to check if it is odd. But he was like 'Don't check NOT conditions. Have the practice of checking the 'trueness' or 'equality' of conditions whenever possible.' And he recommended that I use the second piece of code. I am not for or against either but I just wanted to know - what difference does it make? Please don't reply 'Technically the output will be the same' - we ALL know that. Is it a general programming practice or is it his own programming practice that he is preaching to others?

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  • Practice of checking 'trueness' or 'equality' of conditional statements - does it really make sense?

    - by senthilkumar1033
    I remember many years back, when I was in school, one of my computer science teachers taught us that it was better to check for 'trueness' or 'equality' of a condition and not the negative stuff like 'inequality'. Let me elaborate - If a piece of conditional code can be written by checking whether an expression is true or false, we should check the 'trueness'. Example: Finding out whether a number is odd - it can be done in two ways: if ( num % 2 != 0 ) { // Number is odd } or if ( num % 2 == 1 ) { // Number is odd } When I was beginning to code, I knew that num % 2 == 0 implies the number is even, so I just put a ! there to check if it is odd. But he was like 'Don't check NOT conditions. Have the practice of checking the 'trueness' or 'equality' of conditions whenever possible.' And he recommended that I use the second piece of code. I am not for or against either but I just wanted to know - what difference does it make? Please don't reply 'Technically the output will be the same' - we ALL know that. Is it a general programming practice or is it his own programming practice that he is preaching to others?

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  • Is this common practice for disk quotas on virtual dedicated servers?

    - by Louis
    Hello, I was a bit surprised when I purchased a VPS with 15GB of storage to find that am left with very little space after Windows' 13GB footprint. I can't even install SQL Server. Tech support is saying this is normal. I know that if they felt like it they could remove Windows from the quota or adjust it accordingly. Is this a common practice or should I further pursue the issue with customer service?

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  • Prepare For Oracle Certification Exams With Confidence

    - by Brandye Barrington
    Empower yourself to put your best foot forward on exam day! Oracle Certification Exam Candidates, test with confidence using preparation tools created by Oracle and Oracle's only Authorized Practice Test Provider, Kaplan SelfTest. Oracle wants to help protect your investment of time and money by offering tools to help you be as prepared as possible for your certification exam as well as your future job role. Use these valuable tools to get the most out of your exam preparation: Online Exam Preparation Seminars, Online Practice Tests and the new free Online Demos from Kaplan SelfTest. FREE ONLINE DEMOS Choose from 1Z0-851 Java 6 Programmer Certified Professional or 1Z0-047 Oracle Database SQL Expert. Get a feel for the type and difficulty of questions on the Oracle Certification exams and determine if you are ready for the exam or if you need more preparation. This is a powerful tool that will help you plan your preparation and make the most of your investment. Access Free Online Demos Now ONLINE EXAM PREPARATION SEMINARS These one-day self-paced streaming video seminars are 100% focused on exam preparation. The streaming video format lets you fast forward, rewind, and replay at your own pace so that you can identify and close any knowledge gaps before taking the exam. The Exam Prep Seminar structures your studying - so you don't have to. Access Online Exam Preparation Seminars ONLINE PRACTICE TESTS Test your knowledge with Kaplan SelfTest Practice Exams. These practice tests are one of the most effective ways to prepare for your Oracle Certification exam by helping you self-assess your knowledge using realistic exam simulations. You can purchase practice exams from Oracle with 30-day or 12-month access. Access Online Practice Tests Approach exam day with confidence using the tools above.

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  • SQL Server data platform upgrade - Why upgrade and how best you can reduce pre & post upgrade problems?

    - by ssqa.net
    SQL Server upgrade, let it be database(s) or instance(s) or both the process and procedures must follow best practices in order to reduce any problems that may occur even after the platform is upgraded. The success of any project relies upon the simpler methods of implementation and a process to reduce the complexity in testing to ensure a successful outcome. Also the topic has been a popular topic that .... read more from here ......(read more)

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  • What problems will I face if I remove the concept of interfaces from my code?

    - by Vishwas Gagrani
    I have been programming for many years but I am still not comfortable with the concept of "Interfaces". I try to use interfaces but many times I don't see a mandatory use for it. I think this is probably because the projects weren't so big, or because interfaces are more useful when teamwork is involved. So, making another attempt to understand the importance of interfaces, here is my question: What problems will I face if I remove the concept of interfaces from my code?

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  • How can I solve the same problems a CB-architecture is trying to solve without using hacks? [on hold]

    - by Jefffrey
    A component based system's goal is to solve the problems that derives from inheritance: for example the fact that some parts of the code (that are called components) are reused by very different classes that, hypothetically, would lie in a very different branch of the inheritance tree. That's a very nice concept, but I've found out that CBS is often hard to accomplish without using ugly hacks. Implementations of this system are often far from clean. But I don't want to discuss this any further. My question is: how can I solve the same problems a CBS try to solve with a very clean interface? (possibly with examples, there are a lot of abstract talks about the "perfect" design already). Here's an example I was going for before realizing I was just reinventing inheritance again: class Human { public: Position position; Movement movement; Sprite sprite; // other human specific components }; class Zombie { Position position; Movement movement; Sprite sprite; // other zombie specific components }; After writing that I realized I needed an interface, otherwise I would have needed N containers for N different types of objects (or to use boost::variant to gather them all together). So I've thought of polymorphism (move what systems do in a CBS design into class specific functions): class Entity { public: virtual void on_event(Event) {} // not pure virtual on purpose virtual void on_update(World) {} virtual void on_draw(Window) {} }; class Human { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; class Zombie { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; Which was nice, except for the fact that now the outside world would not even be able to know where a Human is positioned (it does not have access to its position member). That would be useful to track the player position for collision detection or if on_update the Zombie would want to track down its nearest human to move towards him. So I added const Position& get_position() const; to both the Zombie and Human classes. And then I realized that both functionality were shared, so it should have gone to the common base class: Entity. Do you notice anything? Yes, with that methodology I would have a god Entity class full of common functionality (which is the thing I was trying to avoid in the first place).

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  • What implementation problems are still soaking up all of your time?

    - by Conor
    What implementation problems has the industry claimed to have solved many times, but are still soaking up all of your time? Examples: Cross platform GUI - mobile devices have blown this issue wide open. OO to RDBMS mapping - how do I map this attribute to that field in that database using that framework. You get the idea. Interface definitions - ..., CORBA, COM, EJB, WSDL, ..., etc Can you think of any others?

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  • W: Duplicate sources.list entry : You may want to run apt-get update to correct these problems [closed]

    - by Peter Schriver
    Possible Duplicate: W: Duplicate sources.list entry http://archive.ubuntu.com/ubuntu/ precise-updates/main i386 Packages W: Duplicate sources.list entry http://us.archive.ubuntu.com/ubuntu/ quantal-updates/multiverse i386 Packages (/var/lib/apt/lists/us.archive.ubuntu.com_ubuntu_dists_quantal-updates_multiverse_binary-i386_Packages) W: You may want to run apt-get update to correct these problems I keep getting this message and sudo apt-get update doesn't fix it. I am running 64-bit 12.10. Is there a way to correct this problem?

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  • Data Structures: What are some common examples of problems where "buffers" come into action?

    - by Dark Templar
    I was just wondering if there were some "standard" examples that everyone uses as a basis for explaining the nature of a problem that requires the use of a buffer. What are some well-known problems in the real world that can see great benefits from using a buffer? Also, a little background or explanation as to why the problem benefits from using a buffer, and how the buffer would be implemented, would be insightful for understanding the concept!

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  • What would be a good set of first programming problems that would help a non-CS graduate to learn programming ?

    - by shan23
    I'm looking at helping a friend learn programming (I'm NOT asking about the ideal first language to learn programming in). She's had a predominantly mathematical background (majoring in Maths for both her undergrads and graduate degree), and has had some rudimentary exposure to programming before (in the form of Matlab simulations/matrix operations in C etc) - but has never been required to design/execute complex projects. She is primarily interested in learning C/C++ - so, with respect to her background, what would be a set of suitable problems that would both engage her interest ?

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  • What common programming problems are best solved by using prototypes and closures?

    - by vemv
    As much as I understand both concepts, I can't see how can I take advantage of JavaScript's closures and prototypes aside from using them for creating instantiable and/or encapsulated class-like blocks (which seems more of a workaround than an asset to me) Other JS features such as functions-as-values or logical evaluation of non-booleans are much easier to fall in love with... What common programming problems are best solved by using propotypal inheritance and closures?

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  • Is it a bad practice to add extra attributes to html elements?

    - by burak ozdogan
    Hi, Sometimes I add an attribute to some of my controls. Like: <a href id="myLlink" isClimber="True">Chris Sharma</a> I know it is not a valid html. But it helps me in some cases. Is this considered as a bad practice? A friend of mine says that it is ok for Intranet environment but on internet it might not be find friendly by search engines. If it is not a good practice, what are the best practicess? Thanks

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  • Is it good practice to call module functions directly in VB.NET?

    - by froadie
    I have a Util module in my VB.NET program that has project-wide methods such as logging and property parsing. The general practice where I work seems to be to call these methods directly without prefixing them with Util. When I was new to VB, it took me a while to figure out where these methods/functions were coming from. As I use my own Util methods now, I can't help thinking that it's a lot clearer and more understandable to add Util. before each method call (you know immediately that it's user-defined but not within the current class, and where to find it), and is hardly even longer. What's the general practice when calling procedures/functions of VB modules? Should we prefix them with the module name or not?

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  • Is it bad practice to extend the MongoEngine User document?

    - by Soviut
    I'm integrating MongoDB using MongoEngine. It provides auth and session support that a standard pymongo setup would lack. In regular django auth, it's considered bad practice to extend the User model since there's no guarantee it will be used correctly everywhere. Is this the case with mongoengine.django.auth? If it is considered bad practice, what is the best way to attach a separate user profile? Django has mechanisms for specifying an AUTH_PROFILE_MODULE. Is this supported in MongoEngine as well, or should I be manually doing the lookup?

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  • Is it bad practice to assign a css class for the sole purpose of finding it with jQuery?

    - by user187305
    I'm using ASP.NET, not the newest one with that clientIdMode stuff. So, the control ids are generated and funky. There are lots of ways of passing ids around, but lately I've been assigning a 'fake' css class to the control I'm interested in. Then in a js file I use jQuery to find the control. Is this bad practice? It seems a lot like the ajaxControlToolkit's behaviorId to me... Is the behaviorId bad practice as well?

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  • is it good practice to use iframe to implement header/navbar?

    - by Xah Lee
    is it good practice to use iframe to implement header/navbar? my website is basically 5 thousand pages but all static html (not using any content manager, php, etc.). am in the process to add a navbar at the top of each page. e.g. tabs, or crumbs, or any sort of header with js menu. (the exact design not decided yet) my question is, is it good practice to use a iframe for this? (so, instead have same text repeated in all 5 thousand pages, each will just have a short iframe pointing to a header file) am aware that one should reduce http request for speed, but this is ok with me. Any other problems i might have with this? SEO or any tech issue?

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  • How to Tell a Hardware Problem From a Software Problem

    - by Chris Hoffman
    Your computer seems to be malfunctioning — it’s slow, programs are crashing or Windows may be blue-screening. Is your computer’s hardware failing, or does it have a software problem that you can fix on your own? This can actually be a bit tricky to figure out. Hardware problems and software problems can lead to the same symptoms — for example, frequent blue screens of death may be caused by either software or hardware problems. Computer is Slow We’ve all heard the stories — someone’s computer slows down over time because they install too much software that runs at startup or it becomes infected with malware. The person concludes that their computer is slowing down because it’s old, so they replace it. But they’re wrong. If a computer is slowing down, it has a software problem that can be fixed. Hardware problems shouldn’t cause your computer to slow down. There are some rare exceptions to this — perhaps your CPU is overheating and it’s downclocking itself, running slower to stay cooler — but most slowness is caused by software issues. Blue Screens Modern versions of Windows are much more stable than older versions of Windows. When used with reliable hardware with well-programmed drivers, a typical Windows computer shouldn’t blue-screen at all. If you are encountering frequent blue screens of death, there’s a good chance your computer’s hardware is failing. Blue screens could also be caused by badly programmed hardware drivers, however. If you just installed or upgraded hardware drivers and blue screens start, try uninstalling the drivers or using system restore — there may be something wrong with the drivers. If you haven’t done anything with your drivers recently and blue screens start, there’s a very good chance you have a hardware problem. Computer Won’t Boot If your computer won’t boot, you could have either a software problem or a hardware problem. Is Windows attempting to boot and failing part-way through the boot process, or does the computer no longer recognize its hard drive or not power on at all? Consult our guide to troubleshooting boot problems for more information. When Hardware Starts to Fail… Here are some common components that can fail and the problems their failures may cause: Hard Drive: If your hard drive starts failing, files on your hard drive may become corrupted. You may see long delays when you attempt to access files or save to the hard drive. Windows may stop booting entirely. CPU: A failing CPU may result in your computer not booting at all. If the CPU is overheating, your computer may blue-screen when it’s under load — for example, when you’re playing a demanding game or encoding video. RAM: Applications write data to your RAM and use it for short-term storage. If your RAM starts failing, an application may write data to part of the RAM, then later read it back and get an incorrect value. This can result in application crashes, blue screens, and file corruption. Graphics Card: Graphics card problems may result in graphical errors while rendering 3D content or even just while displaying your desktop. If the graphics card is overheating, it may crash your graphics driver or cause your computer to freeze while under load — for example, when playing demanding 3D games. Fans: If any of the fans fail in your computer, components may overheat and you may see the above CPU or graphics card problems. Your computer may also shut itself down abruptly so it doesn’t overheat any further and damage itself. Motherboard: Motherboard problems can be extremely tough to diagnose. You may see occasional blue screens or similar problems. Power Supply: A malfunctioning power supply is also tough to diagnose — it may deliver too much power to a component, damaging it and causing it to malfunction. If the power supply dies completely, your computer won’t power on and nothing will happen when you press the power button. Other common problems — for example, a computer slowing down — are likely to be software problems. It’s also possible that software problems can cause many of the above symptoms — malware that hooks deep into the Windows kernel can cause your computer to blue-screen, for example. The Only Way to Know For Sure We’ve tried to give you some idea of the difference between common software problems and hardware problems with the above examples. But it’s often tough to know for sure, and troubleshooting is usually a trial-and-error process. This is especially true if you have an intermittent problem, such as your computer blue-screening a few times a week. You can try scanning your computer for malware and running System Restore to restore your computer’s system software back to its previous working state, but these aren’t  guaranteed ways to fix software problems. The best way to determine whether the problem you have is a software or hardware one is to bite the bullet and restore your computer’s software back to its default state. That means reinstalling Windows or using the Refresh or reset feature on Windows 8. See whether the problem still persists after you restore its operating system to its default state. If you still see the same problem – for example, if your computer is blue-screening and continues to blue-screen after reinstalling Windows — you know you have a hardware problem and need to have your computer fixed or replaced. If the computer crashes or freezes while reinstalling Windows, you definitely have a hardware problem. Even this isn’t a completely perfect method — for example, you may reinstall Windows and install the same hardware drivers afterwards. If the hardware drivers are badly programmed, the blue-screens may continue. Blue screens of death aren’t as common on Windows these days — if you’re encountering them frequently, you likely have a hardware problem. Most blue screens you encounter will likely be caused by hardware issues. On the other hand, other common complaints like “my computer has slowed down” are easily fixable software problems. When in doubt, back up your files and reinstall Windows. Image Credit: Anders Sandberg on Flickr, comedy_nose on Flickr     

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  • What is a ‘best practice’ backup plan for a website?

    - by HollerTrain
    I have a website which is very large and has a large user-base. I am trying to think of a 'best practice' way to create a back up or mirror website, so if something happens on domain.com, I can quickly point the site to backup.domain.com via 401 redirect. This would give me time to troubleshoot domain.com while everyone is viewing backup.domain.com and not knowing the difference. Is my method the ideal method, or have you enacted better methods to creating a backup site? I don't want to have the site go down and then get yelled at every minute while I'm trying to fix it. Ideally I would just 'flip the switch' and it would redirect the user to a backup. Any insight would be greatly appreciated.

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  • Memcached server: Is it a good practice to point two server urls to the same server?

    - by Niro
    I have a system where there are connections to a memcache server from several different files and servers. I would like to stay with one server but keep the option of increasing the number of memcache servers (for periods of of high traffic). My idea is to tell memcache there are two servers, while the two urls will point (by DNS) to a single server. In the future if I want I can add a server and change DNS without changing the code in many places. Is this a good practice? Is there a performance cost to the fact that there are two server connections but they both point to the same server? Any other idea how to achive instant expeandability of memcache capacity without need to change the code and deploy ?

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  • What is a 'best practice' backup plan for a website?

    - by HollerTrain
    I have a website which is very large and has a large user-base. I am trying to think of a 'best practice' way to create a back up or mirror website, so if something happens on domain.com, I can quickly point the site to backup.domain.com via 401 redirect. This would give me time to troubleshoot domain.com while everyone is viewing backup.domain.com and not knowing the difference. Is my method the ideal method, or have you enacted better methods to creating a backup site? I don't want to have the site go down and then get yelled at every minute while I'm trying to fix it. Ideally I would just 'flip the switch' and it would redirect the user to a backup. Any insight would be greatly appreciated.

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