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• Why is thread local storage so slow?

  - by dsimcha

  I'm working on a custom mark-release style memory allocator for the D programming language that works by allocating from thread-local regions. It seems that the thread local storage bottleneck is causing a huge (~50%) slowdown in allocating memory from these regions compared to an otherwise identical single threaded version of the code, even after designing my code to have only one TLS lookup per allocation/deallocation. This is based on allocating/freeing memory a large number of times in a loop, and I'm trying to figure out if it's an artifact of my benchmarking method. My understanding is that thread local storage should basically just involve accessing something through an extra layer of indirection, similar to accessing a variable via a pointer. Is this incorrect? How much overhead does thread-local storage typically have? Note: Although I mention D, I'm also interested in general answers that aren't specific to D, since D's implementation of thread-local storage will likely improve if it is slower than the best implementations.

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• Throwing an exception while handling an exception

  - by FredOverflow

  If a destructor throws in C++ during stack unwinding caused by an exception, the program terminates. (That's why destructors should never throw in C++.) If a finally block is entered in Java because of an exception in the corresponding try block and that finally block throws another exception, the first exception is silently swallowed. This question crossed my mind: Could a programming language handle multiple exceptions being thrown at the same time? Would that be useful? Have you ever missed that ability? Is there a language that already supports this? Is there any experience with such an approach? Any thoughts?

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• Handling User Authentication in C#.NET?

  - by Daniel

  I am new to .NET, and don't have much experience in programming. What is the standard way of handling user authentication in .NET in the following situation? 1.In Process A, User inputs ID/Password 2.Process A sends the ID/Password to Process B over a nonsecure public channel. 3.Process B authenticates the user with the recieved ID/Password what are some of the standard cryptographic algorithms I can use in above model? The users(customers that bought my company's software) will be running the software(Process A) locally in their computer(connected to internet). I need to authenticate the users so that only registered users can run the program. Thank You!

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• Metaprograming - self explanatory code - tutorials, articles, books

  - by elena

  Hello everybody, I am looking into improving my programming skils (actually I try to do my best to suck less each year, as our Jeff Atwood put it), so I was thinking into reading stuff about metaprogramming and self explanatory code. I am looking for something like an idiot's guide to this (free books for download, online resources). Also I want more than your average wiki page and also something language agnostic or preferably with Java examples. Do you know of such resources that will allow to efficiently put all of it into prectice (I know experience has a lot to say in all of this but i kind of want to build experience avoiding the flow bad decitions - experience - good decitions)? Thank you!

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• How do you keep a balance between working, training, health and family?

  - by Jim Burger

  One trend I see in the awesome developers I've met, is that they devote inordinate amounts of time to coding at the expense of (usually) their health. Personally, I also find it hard to motivate myself to keep healthy. Every now and again, I meet a fantastic coder who has it clocked; they are up to date with the latest dev news, have time to read about good programming practices, and to finish it off, have happy wives/husbands and families. How do you guys/gals manage it in the short 24 hours a day that we all have?

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• Adding JPanel onto another JPanel after button click

  - by user1400650

  I'm using Netbeans IDE to make a gui application. I have a JFrame with a JPanel inside it. After a button click I want to display a different JPanel inside the first. The other JPanel is in a different file. How would I go about doing this? If this is not practical I don't mind replacing the first JPanel with the second one. I've tried the following but it doesn't seem to work. I'm new to Java and Gui programming so I would appreciate any help I can get. private void jButtonActionPerformed(java.awt.event.ActionEvent evt) { JPanel2 jPanel2 = new JPanel2(); JPanel1.add(jPanel2); }

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• .NET Active Directory Password Expiration on Windows 2008

  - by Brent Pabst

  Searched SO and Everywhere else, including the .net developers guide to directory services programming book - no luck. I am trying to create a simple password reset web page that allows the user to change their password. The change password portion of the code is working fine. For the users I would also like to display when their current password will expire next. Using the sample code from the book mentioned above I was able to get all of the code setup however, the attribute that is returned is always equal to Long.MinValue and hence cannot be inverted to a positive number, plus this means it did not find the proper domain setting. Does anyone have sample code or references for getting the password expiration in a Windows 2008 or R2 domain environment where password policies can be different for each user?

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• multiplayer / visitors interactions with Ruby on Rails?

  - by Jordi

  I want to have interactions between visitors on my site. Imagine a chat room. It basically involves getting the data from everyone and sending it to everyone, this can be done by ajax and what not but I wonder if there is something already there in the wild that would do the heavy lifting for me. I have to say that I got very lost once I start programming Ajax, dont even know how to make tests for it... I have found the Q42multiplayer library that looks like what I want but they use C# as backend. There is something similar or any other multiplayer thingy I can get some idea or rip some code from (the whole thing will be opensource) for Ruby on Rails?

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• Help a Python newbie with a Django model inheritance problem

  - by Joshmaker

  I'm working on my first real Django project after years of PHP programming, and I am running into a problem with my models. First, I noticed that I was copying and pasting code between the models, and being a diligent OO programmer I decided to make a parent class that the other models could inherit from: class Common(model.Model): self.name = models.CharField(max_length=255) date_created = models.DateTimeField(auto_now_add=True) date_modified = models.DateTimeField(auto_now=True) def __unicode__(self): return self.name class Meta: abstract=True So far so good. Now all my other models extend "Common" and have names and dates like I want. However, I have a class for "Categories" were the name has to be unique. I assume there should be a relatively simple way for me to access the name attribute from Common and make it unique. However, the different methods I have tried to use have all failed. For example: class Category(Common): def __init__(self, *args, **kwargs): self.name.unique=True Spits up the error "Caught an exception while rendering: 'Category' object has no attribute 'name' Can someone point me in the right direction?

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• What web browser engine, version, and capabilities are used to display web pages inside Visual Studio 2010?

  - by Phrogz

  My company is developing a plugin/add-on for Visual Studio 2010. When the user asks to display the help for our product, we plan on opening an HTML page (or suite of pages) within Visual Studio. I'm helping to design and implement the help system. What web engine/version is used within Visual Studio 2010? According to Wikipedia it is not Trident(!). Am I allowed to load remote JavaScript content (via a <script> element)? Am I allowed to use XHR to load remote content? Will my page be trusted and have access to the FileSystemObject? I would appreciate any resources you can give me on programming specifically to the 'web' capabilities of VisualStudio2010-as-a-browser.

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• use multiple views in an application

  - by Gaurav Arora

  Hi All, I am new to Iphone programming. So please don't mind if I ask some basic questions. :mad: I want to develop an application where the landing screen will be a login screen and after login application should display a new screen with the list of available categories. And on selecting any category a new screen should appear with the information related to the selected category. Basically I want to display different screens in the applications and my confusion is how can I make different screens with one .xib file? or should I use different .xib files for each screen. If I use different .xib files for each screen then how should I navigate to different screens. Please help in solving this confusion. Thanks in advance Gaurav

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• Comparing Clojure books

  - by Michiel Borkent

  Currently there is (afaik) one completed Clojure book available: Programming Clojure by Stuart Halloway. Two are being written and partially available at Manning: The Joy of Clojure by Fogus and Houser Clojure in Action by Amit Rathore Another one is about to be published in May: Practical Clojure (The Definitive Guide) by Luke Van der Hart Are these books more or less the same and meant as a general introduction to Clojure? Does it make sense to buy them all, or is there a risk of having three very similar books? Will there be books that go into more specialized areas of Clojure and targetted for 'intermediate' or 'advanced' Clojure programmers?

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• C-array to NSData and back

  - by Thor Frølich

  I'm attempting to save a c-style array of Vertex3D structs to an NSData object and get them back when reloading the app: NSData *vert = [NSData dataWithBytes:&vertices length:(sizeof(Vertex3D) * NUM_OF_VERTICES)]; This data is then saved and attempted to be read back into my c-array thusly: vertices = malloc(sizeof(Vertex3D) * NUM_OF_VERTICES); [vert getBytes:&vertices length:(sizeof(Vertex3D) * NUM_OF_VERTICES)]; The above results in “EXC_BAD_ACCESS” followed by: malloc: * error for object 0x48423c0: pointer being freed was not allocated I'm very new to programming so there's probably some fundamental memory management principle I'm unaware of. I have verified that the loaded NSData is identical to the saved one, but it's clear that the transition from c-array to NSData (and back) is not as I intended.

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• Why is my app running

  - by John Smith

  I have compiled my iPhone app with setting (Device, Release). I install it on the test machine and it runs with no problem. Here's the problem. The app is linked to a C++ library. The compilation on the simulator has no errors. However the device compilation produces 568 errors, mostly about different visibilities w.r.t AppDelegate.o. They all look like: QL::Error::~Error()has different visibility (default) in /QL/build/Release-iphoneos/libQLLibrary.a(abcd.o) and (hidden) in /Programming/ObjC/Second/build/Second.build/Release-iphoneos/FG.build/Objects-normal/armv6/AppDelegate.o Why is this, and how can I stop the errors anyway?

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• Technologies used in Remote Administration applications(not RD)

  - by Michael

  I want to know what kind of technologies are used nowadays as underlying screen capture engine for remote administration software like VNC pcAnywhere TeamViewer RAC Remote Administrator etc.. The programming language is not so important as just to know whether a driver needs to be developed which is polling video memory 30 times per second or there are any com objects built in the Windows kernel to help doing this? I'm not interested in 3rd party components for doing this. Do I have to use DirectX facilities? Just want some start point to develop my own screen stream capture engine, which will be less CPU hog.

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• Eclipse IDE's Hello World Cheatsheet seems to have a mistake

  - by Sean

  Hey guys, Just a warning: I'm completely new to Java and am trying to teach myself Android programming. I installed the Eclipse IDE today and tried to walk through the first Java Hello World "cheat sheet," and it didn't work! I was really quite surprised. When it asked me to select the checkbox to create the main() method, there wasn't anything on-screen that looked like a checkbox with "main()" or "method" next to it, so I guessed that maybe what they meant was the "Modifiers" radio button. So I left that checked for "public." It didn't compile and I got red X's next to every folder in my Package Explorer. Has anybody else had this problem? Thanks!

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• Return a pointer to a char array in C

  - by snitko

  I've seen a lot of questions on that on StackOverflow, but reading the answers did not clear that up for me, probably because I'm a total newbie in C programming. Here's the code: #include <stdio.h> char* squeeze(char s[], char c); main() { printf("%s", squeeze("hello", 'o')); } char* squeeze(char s[], char c) { int i, j; for(i = j = 0; s[i] != '\0'; i++) if(s[i] != c) s[j++] = s[i]; s[j] = '\0'; return s; } It compiles and I get segmentation fault when I run it. I've read this faq about about returning arrays and tried the 'static' technique that is suggested there, but still could not get the program working. Could anyone point out exactly what's wrong with it and what should I be paying attention in the future?

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• Warning: Ignoring library 'com.motorola.android.iextdispservice', missing property value

  - by user1342684

  Hi I am trying to get my eclipse environment setup so I can start playing with programming for android... The Android SDK Manager is installing the following packages (everything else says installed except these two): Android 2.3.3 (API 10) Dual Screen APIs - Not Installed Android 2.2 (API 8) Dual Screen APIs - Not Installed Error Messages: [2012-04-19 13:06:41 - SDK Manager] Warning: Ignoring library 'com.motorola.android.iextdispservice', missing property value [2012-04-19 13:15:27 - SDK Manager] Operation timed out [2012-04-19 13:18:16 - SDK Manager] Operation timed out Any tips? So close to getting the environment ready! I want to start playing around!

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• Load XML to DataFrame in R

  - by Rohit Kandhal

  I am new to R programming and trying to load a simple XML in RStudio. I tried using XMLToDataFrame but got this error XML content does not seem to be XML: 'temp.xml' XML Schema <root> <row Id="1" UserId="1" Name="Rohit" Date="2009-06-29T10:28:58.013" /> <row Id="2" UserId="3" Name="Rohit" Date="2009-06-29T10:28:58.030" /> </root> Please provide me some direction on which function I should use here.

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• Project roles discovery

  - by Lirik

  I have a school project in which we're going to write a financial engine prototype by a group of 4 people. Most of us have never met each other before, so I'm trying to create a questionnaire to help us find the appropriate roles for each team-member. We have the following responsibilities: Database design Programming User interface design Training Documentation / technical writing Network design Project management Business analysis Testing And we have the following roles: Project Manager Developer Tester Business Analyst Our group has people with various experience: a full-time graduate student, an associate director at the CME (Chicago Mercantile Exchange), full-time professionals, etc. Do any of you know of any tools that would help build a questionnaire or do you have a reference to an online questionnaire that can help us identify the most suitable role(s) for each team member?

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• What learning habits can you suggest?

  - by Asaf R

  Hi, Our profession often requires deep learning; sitting down and reading, and understanding. I'm currently undergoing an exam period, and I'm looking for ways to learn more effectively. I'm not asking about what to learn, or whether to prefer blogs over books, etc. My question is much more physical than that - What do you do when need to study, and I mean study hard? I'm looking for answers such as I slice my time to 2.5 hours intervals and make a break between them, but never during. I keep a jar of water nearby. I wake up at 6 o'clock sharp and start my day with a session at the gym. What good learning habits did acquire, or wish you had acquired? (I know this isn't strictly programming related, but it is programmers related)

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• Spinlocks, How Much Useful Are They?

  - by unknown

  How often do you find yourself actually using spinlocks in your code? How common is it to come across a situation where using a busy loop actually outperforms the usage of locks? Personally, when I write some sort of code that requires thread safety, I tend to benchmark it with different synchronization primitives, and as far as it goes, it seems like using locks gives better performance than using spinlocks. No matter for how little time I actually hold the lock, the amount of contention I receive when using spinlocks is far greater than the amount I get from using locks (of course, I run my tests on a multiprocessor machine). I realize that it's more likely to come across a spinlock in "low-level" code, but I'm interested to know whether you find it useful in even a more high-level kind of programming?

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• Behavior of a pipe after a fork()

  - by Steve Melvin

  When reading about pipes in Advanced Programming in the UNIX Environment, I noticed that after a fork that the parent can close() the read end of a pipe and it doesn't close the read end for the child. When a process forks, does its file descriptors get retained? What I mean by this is that before the fork the pipe read file descriptor had a retain count of 1, and after the fork 2. When the parent closed its read side the fd went to 1 and is kept open for the child. Is this essentially what is happening? Does this behavior also occur for regular file descriptors?

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• Facebook API - Get comments

  - by Simon R

  Our business has a Facebook Fan Page. The fan page doesn't seem to generate any emails to us when updates are made to the page, whether someone adds a new status or someone comments on one of the statuses etc. Currently, we are running a very crude script to grab the content of the page and then use regular expressions to get the information we require. Obviously this is not fool proof and I'm looking into alternatives to this method. I've been looking at the facebook API and wonder if the rest server might be an option. I cannot, however, seem to find out how to return information of fan page statuses and their comments. Is anyone able to direct me how to use the API to retrieve this information. I am an admin of the fan page. The programming language I'm using is PHP. Many thanks.

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• Perspective Rotation about Y axis

  - by N.A.Reddy

  Hello Experts, I have a 2D image and I want to create a anaglyph image for this single 2D image. To do this I need to create Left and Right views. I will considar my 2D image as Left view and I want to create Right View now. I came to know that the perspective rotation (about Y axis) and perspective skews will give the right image. I know that the perspective projection is related to 3D. Basically I am new to 3D programming. Can you plz explain how to do perspective rotation abuout Y-axis. And how can I apply this to my 2D image.I am using C++. Thank you verymuch N.A.Reddy.

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