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  • Can Ruby Fibers be Concurrent?

    - by Jesse J
    I'm trying to get some speed up in my program and I've been told that Ruby Fibers are faster than threads and can take advantage of multiple cores. I've looked around, but I just can't find how to actually run different fibers concurrently. With threads you can dO this: threads = [] threads << Thread.new {Do something} threads << Thread.new {Do something} threads.each {|thread| thread.join} I can't see how to do something like this with fibers. All I can find is yield and resume which seems like just a bunch of starting and stopping between the fibers. Is there a way to do true concurrency with fibers?

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  • Database query optimization

    - by hdx
    Ok my Giant friends once again I seek a little space in your shoulders :P Here is the issue, I have a python script that is fixing some database issues but it is taking way too long, the main update statement is this: cursor.execute("UPDATE jiveuser SET username = '%s' WHERE userid = %d" % (newName,userId)) That is getting called about 9500 times with different newName and userid pairs... Any suggestions on how to speed up the process? Maybe somehow a way where I can do all updates with just one query? Any help will be much appreciated! PS: Postgres is the db being used.

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  • C++ and Scripting.Dictionary from scrrun.dll

    - by MaxFX
    Hello. I have some trouble with Scripting.Dictionary in C++. I'm trying to use interface IDictionary via smart pointer but methods of creating object don't work and I can't understand why. CoInitialize(NULL); IDictionaryPtr dict; dict.CreateInstance(__uuidof(Dictionary)); _variant_t num1 = 1; _variant_t num2 = 2; dict->Add(&num1, &num2); long i; dict->get_Count(&i); cout << i << "\n"; But method Add does not work and cout of elements in dictionary is always 0. How correct to use Scripting.Dictionary in that case. PS.: I'm getting Scripting interfaces by #import "scrrun.dll"

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  • Zend_Cache_Backend_Sqlite vs Zend_Cache_Backend_File

    - by Alekc
    Hi, Currently i'm using Zend_Cache_Backend_File for caching my project (especially responses from external web services). I was wandering if I could find some benefit in migrating the structure to Zend_Cache_Backend_Sqlite. Possible advantages are: File system is well-ordered (only 1 file in cache folder) Removing expired entries should be quicker (my assumption, since zend wouldn't need to scan internal-metadatas for expiring date of each cache) Possible disadvantages: Finding record to read (with files zend check if file exists based on filename and should be a bit quicker) in term of speed. I've tried to search a bit in internet but it seems that there are not a lot of discussion about the matter. What do you think about it? Thanks in advance.

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  • maths: motion depending on time

    - by clamp
    hello, i have a mathematical problem: i have a function where the only parameter is the current time. the return should be a position which is used to place an object on a certain place. int position(int time) { int x = 0; //TODO implement x depending on time return x; } so basically the function is called every frame to put the object in motion. the motion should look like this (this is the actual question): a linear motion for time A, the object moves at constant speed no motion for time B, the object is stopped repeat at 1. thanks!

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  • Switching to a VPS

    - by Damian
    Well, I know absolutely nothing about the subject, so I really need help. I currently have a website running on google app-engine (Java) and I can't get it to what I want because of app engine's limitations (no full text search mainly). The traffic is low, never reached 15% of the free quota (around 1500 daily pageviews). I also have 3 sites in drupal hosted in a shared hosting service, and this is giving me problems, because the server speed is awful. The sites are VERY low trafic, but load times are bad, and I might need to add more sites for some clients, so this will only get worse. So, i'm planning to move all that to VPS. The question is, can I have 2 http servers running in the same VPS? because I will need Apache-php-drupal server and a java server (tomcat?). I have really no idea on this, so any tip will be very helpful to me. Thanks!

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  • How I do I make controls/elements move with inertia?

    - by Kris Erickson
    Modern UI's are starting to give their UI elments nice inertia when moving. Tabs slide in, page transitions, even some listboxes and scroll elments have nice inertia to them (the iphone for example). What is the best algorythm for this? It is more than just gravity as they speed up, and then slow down as they fall into place. I have tried various formulae's for speeding up to a maximum (terminal) velocity and then slowing down but nothing I have tried "feels" right. It always feels a little bit off. Is there a standard for this, or is it just a matter of playing with various numbers until it looks/feels right?

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  • Entity Framework VS LINQ to SQL VS ADO.NET with stored procedures?

    - by BritishDeveloper
    How would you rate each of them in terms of: Performance Speed of development Neat, intuitive, maintainable code Flexibility Overall I like my SQL and so have always been a die-hard fan of ADO.NET and stored procedures but I recently had a play with Linq to SQL and was blown away by how quickly I was writing out my DataAccess layer and have decided to spend some time really understanding either Linq to SQL or EF... or neither? I just want to check, that there isn't a great flaw in any of these technologies that would render my research time useless. E.g. performance is terrible, it's cool for simple apps but can only take you so far

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  • How to randomize a sorted list?

    - by Faken
    Here's a strange question for you guys, I have a nice sorted list that I wish to randomize. How would i go about doing that? In my application, i have a function that returns a list of points that describe the outline of a discretized object. Due to the way the problem is solved, the function returns a nice ordered list. i have a second boundary described in math and want to determine if the two objects intersect each other. I simply itterate over the points and determine if any one point is inside the mathematical boundary. The method works well but i want to increase speed by randomizing the point data. Since it is likely that that my mathematical boundary will be overlapped by a series of points that are right beside each other, i think it would make sense to check a randomized list rather than iterating over a nice sorted one (as it only takes a single hit to declare an intersection). So, any ideas on how i would go about randomizing an ordered list?

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  • Alternative to c++ static virtual methods

    - by Jaime Pardos
    In C++ is not possible to declare a static virtual function, neither cast a non-static function to a C style function pointer. Now, I have a plain ol' C SDK that uses function pointers heavily. I have to fill a structure with several function pointers. I was planning to use an abstract class with a bunch of static pure virtual methods, and redefine them in derived classes and fill the structure with them. It wasn't until then that I realized that static virtual are not allowed in C++. Is there any good alternative? The best I can think of is defining some pure virtual methods GetFuncA(), GetFuncB(),... and some static members FuncA()/FuncB() in each derived class, which would be returned by the GetFuncX(). Then a function in the abstract class would call those functions to get the pointers and fill the structure.

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  • Place an object on top of stack in ILGenerator

    - by KiNGPiN
    I have to pass a function an instance of an object, so obviously all the information to be taken as argument is to be loaded onto the evaluation stack Here is the code that i am looking for someClass SomeObject = new someClass(); il.Emit(OpCodes.LoadObject, SomeObject); il.Emit(OpCodes.CallVirt, MethodInfo Function); public void Function(Object obj) { Type type = typeof(obj); //do something w.r.t to the type } I dont require any information stored in the class just the type and i cannot use any of the primitive types to take my decision on Last i read that i can use a pointer to load the type using some opcodes ... but i am completely lost here, any help or pointers to the right direction would be great :)

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  • Why is .NET faster than C++ in this case?

    - by acidzombie24
    -edit- I LOVE SLaks comment. "The amount of misinformation in these answers is staggering." :D Calm down guys. Pretty much all of you were wrong. I DID make optimizations. It turns out whatever optimizations I made wasn't good enough. I ran the code in GCC using gettimeofday (I'll paste code below) and used g++ -O2 file.cpp and got slightly faster results then C#. Maybe MS didn't create the optimizations needed in this specific case but after downloading and installing mingw I was tested and found the speed to be near identical. Justicle Seems to be right. I could have sworn I use clock on my PC and used that to count and found it was slower but problem solved. C++ speed isn't almost twice as slower in the MS compiler. When my friend informed me of this I couldn't believe it. So I took his code and put some timers onto it. Instead of Boo I used C#. I constantly got faster results in C#. Why? The .NET version was nearly half the time no matter what number I used. C++ version: #include <iostream> #include <stdio.h> #include <intrin.h> #include <windows.h> using namespace std; int fib(int n) { if (n < 2) return n; return fib(n - 1) + fib(n - 2); } int main() { __int64 time = 0xFFFFFFFF; while (1) { int n; //cin >> n; n = 41; if (n < 0) break; __int64 start = __rdtsc(); int res = fib(n); __int64 end = __rdtsc(); cout << res << endl; cout << (float)(end-start)/1000000<<endl; break; } return 0; } C# version: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; using System.ComponentModel; using System.Threading; using System.IO; using System.Diagnostics; namespace fibCSTest { class Program { static int fib(int n) { if (n < 2)return n; return fib(n - 1) + fib(n - 2); } static void Main(string[] args) { //var sw = new Stopwatch(); //var timer = new PAB.HiPerfTimer(); var timer = new Stopwatch(); while (true) { int n; //cin >> n; n = 41; if (n < 0) break; timer.Start(); int res = fib(n); timer.Stop(); Console.WriteLine(res); Console.WriteLine(timer.ElapsedMilliseconds); break; } } } } GCC version: #include <iostream> #include <stdio.h> #include <sys/time.h> using namespace std; int fib(int n) { if (n < 2) return n; return fib(n - 1) + fib(n - 2); } int main() { timeval start, end; while (1) { int n; //cin >> n; n = 41; if (n < 0) break; gettimeofday(&start, 0); int res = fib(n); gettimeofday(&end, 0); int sec = end.tv_sec - start.tv_sec; int usec = end.tv_usec - start.tv_usec; cout << res << endl; cout << sec << " " << usec <<endl; break; } return 0; }

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  • my realtime network receiving time differs a lot, anyone can help?

    - by sguox002
    I wrote a program using tcpip sockets to send commands to a device and receive the data from the device. The data size would be around 200kB to 600KB. The computer is directly connected to the device using a 100MB network. I found that the sending packets always arrive at the computer at 100MB/s speed (I have debugging information on the unit and I also verified this using some network monitoring software), but the receiving time differs a lot from 40ms to 250ms, even if the size is the same (I have a receiving buffer about 700K and the receiving window of 8092 bytes and changing the window size does not change anything). The phenomena differs also on different computers, but on the same computer the problem is very stable. For example, receiving 300k bytes on computer a would be 40ms, but it may cost 200ms on another computer. I have disabled firewall, antivirus, all other network protocol except the TCP/IP. Any experts on this can give me some hints?

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  • What is a flexible, hybrid python collection object?

    - by Naveen
    As a way to get used to python, I am trying to translate some of my code to python from Autohotkey_L. I am immediately running into tons of choices for collection objects. Can you help me figure out a built in type or a 3rd party contributed type that has as much as possible, the functionality of the AutoHotkey_L object type and its methods. AutoHotkey_L Objects have features of a python dict, list, and a class instance. I understand that there are tradeoffs for space and speed, but I am just interested in functionality rather than optimization issues.

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  • How do I create a downscaled copy of an FBO in OpenGL?

    - by Jasper Bekkers
    Hi, In order to speed up some post-processing shaders I'm using, I need to perform these operations on a framebuffer that is smaller in size than the actual window (about 1/4th or more). Most of the effects I want to optimize are simple blurring operations that could be replaced (for a large part) by smaller kernel and bilinear filtering. Thus, I need to create a copy of the current FBO into another one. However, I couldn't find anything, that works, on how to do this. I've tried using glBlitframebufferEXT and rendering a fullscreen quad into the other framebuffer, but both paths result in a black texture as output. How do I go about solving this problem?

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  • How to mark empty in a single element in a float array

    - by Vineeth Mohan
    I have a large float (primitive) array and not every element in the array is filled. How can i mark a particular element as EMPTY. I understand this can be achieved by some special symbols but still i would like to know the standard way. Even if i am using some special symbol , how will i handle a situation where the actual data item is the value of special symbol. In short my question is how to implement the NULL feature in a primitive type array in java. PS - The reason why i am not using Float object is to achieve a high memory and speed performance. Thanks Vineeth

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  • How do I read an arbitrary chunk from a PNG file?

    - by Mason Wheeler
    I've got some custom metadata to put into a PNG file. It's being saved through libpng, and it's not difficult to write out a custom chunk. I just call png_write_chunk with the name, length and data. But I can't see how to get the data back out again. I'd expect there to be a png_read_chunk function that takes a chunk name and returns a pointer to the data or something like that, but there's nothing like that in png.h. Does anyone know how to accomplish this?

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  • How to dynamically replace a method implement in ObjC2?

    - by Abhi
    I am trying to learn how to write plugins using SIMBL. I got my plugin to load with the target application, and also know the method that I wish to override. However, I am not able to use class_getInstanceMethod correctly based on snippets on the Internet. Have things changed in OSX 10.6 and/or ObjC2? The following code from culater.net gives "Dereferencing pointer to incomplete type": BOOL DTRenameSelector(Class _class, SEL _oldSelector, SEL _newSelector) { Method method = nil; // First, look for the methods method = class_getInstanceMethod(_class, _oldSelector); if (method == nil) return NO; method->method_name = _newSelector; return YES; } Is there a complete example of how to override a method using SIMBL plugins? Thanks!

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  • Visual Studio Optimizations

    - by lomaxx
    Visual studio is a pretty awesome IDE, but sometimes you just wish it would go faster. I was wondering if people have any tips or tricks to help speed up visual studio in day to day use. Things that I'm particularly interested in are speeding up build times and switching aspx files from source to design view seem to bring it to a grinding halt. Having said that, I'd be keen to hear anything that anyone uses to make VS run that little bit faster. Edit: Merged answers from related question, covering VS2008SP1. Please include any optimisations specific to the latest IDE.

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  • How can I tell NetBeans to use the latest available version of a JAR for a library?

    - by Freiheit
    I have a Netbeans project with a library defined which includes several JARs. These JARs are versioned like lib\blah\com.blah.wibble.jar_0.6.1.201004161543 . These are nightly builds from another project so that version changes often. I know I can point NetBeans at the specific JARs with the version name, but this means that every time I get a new version I have to update the NetBeans library. I can also strip the version name from the JARs, but this makes it hard to track down bugs. "What version of the blah JARs?" is usually the second thing we ask when we find a bug. Is it possible to tell Netbeans to use included com.blah.wibble.jar_[??????] where ???? is some sort of automatic pointer to use the latest available version?

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  • MySQL, how can I SELECT WHERE one field value doesn't occurs in another?

    - by Jules
    I'm trying to do a search on my test server, speed isn't so important. I want to find if a phrase, the whole contents of one field, occurs in any part (as a whole) doesn't occur in another field. Heres my current query which finds if the phrase does occur SELECT pads.padid, pads.programname, keywords.word FROM Pads JOIN keywords ON Pads.Padid = keywords.Padid WHERE pads.Programname = keywords.word AND RemoveMeDate = '2001-01-01 00:00:00' My problem is that the field word contains other words too. I need to produce a count of where there isn't a keywords record with keywords.word equal to pads.programname ? EDIT: So if I have these records Pads: PadID=3 ProgramName=my prog PadID=4 ProgramName=Bad prog PadID=5 ProgramName=Good prog PadID=6 ProgramName=other prog Keywords: PadID=3 word=fox prog PadID=3 word=pig prog PadID=4 word=big prog PadID=4 word=nice prog PadID=5 word=fox prog PadID=6 word=bad prog PadID=6 word=fox prog The query I want would retun a count of 3 and record 6 has bad prog

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  • Slowness of Netbeans Platform Apps - how to mitigate?

    - by user559298
    Hi, We are developing a commerical application (pretty complex) in java using Netbeans IDE. We have 2 options in netbeans to create it- 1. Develop Java desktop app 2. Netbeans Platform app We have requirement that application startup and response times should be very very fast, should be modular etc. We did Proof of Technology by creating apps using both approaches mentioned above. We found Netbeans platform apps are very slow during startup and during screen navigation compared to pure Swing based desktop apps. We tried to implement suggestions provided at http://wiki.netbeans.org/Category:Performance:FAQ and in other blogs and forums to improve on speed of the app but were not successful. We feel for creating a complex desktop app Netbeans platform app would be better suited, but its not meeting our performance requirements (startup and response times, memory footprints, CPU usage guidelines etc). Can any one guide us on how to mitigate our problem of improving performance of Netbeans Platforms apps? Thanks in advance for your help. -bhan

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  • drupal bootstrap script: how to get list of all nodes of type x?

    - by groovehunter
    hi. I create a custom import and export, at the moment as an external script (via bootstrap), i plan to create a module in a more generic fashion lateron. I am building a frontend for nagios and for our host management and nagios configuration btw. Maybe it might become useful for other environments (networkmanagement) Now i need to know how to get list of all nodes of type x? I want to avoid direct SQL. A suggestion i got was to make an rss and parse it but i acess the drupal db a dozen times to extract various nodes, so it feels strange to do a web request for one thing So what i am looking for as newbie drupal dev is just a pointer to basic search module api for this task TIA florian

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  • Shared Variable Among Ruby Processes

    - by Jesse J
    I have a Ruby program that loads up two very large yaml files, so I can get some speed-up by taking advantage of the multiple cores by forking off some processes. I've tried looking, but I'm having trouble figuring how, or even if, I can share variables in different processes. The following code is what I currently have: @proteins = "" @decoyProteins = "" fork do @proteins = YAML.load_file(database) exit end fork do @decoyProteins = YAML.load_file(database) exit end p @proteins["LVDK"] P displays nil though because of the fork. So is it possible to have the forked processes share the variables? And if so, how?

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  • Learning C++ from scratch in Visual Studio?

    - by flesh
    I need to get up to speed with C++ quite quickly (I've never used it previously) - is learning through Visual Studio (i.e. Managed C++) going to be any use? Or will I end up learning the extensions and idiosyncracies of C++ in VS, rather then the language itself? If learning in VS is not recommended, what platform / IDE do you guys suggest? Edit: Can anyone elaborate on what VS will hide or manage for me when coding unmanaged C++? I really need to be learning things like pointers, garbage collection and all the nuts and bolts of the low level language.. does VS abstract or hide any of this kind of stuff from you? Thanks for all the suggestions..

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