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• JSF Pages call ManagedBeans that are not defined on the page and call all getters sometimes more tha

  - by Bill Leeper

  I have several JSF pages that are initializing and accessing ManagedBeans that are not even used on that page. This is creating a really hairy problem for initialization. I either have to make them all session scope and continually make calls to re-inialize or take the performance hit of having them read large amounts of data from the DB whenever they decide to initialize. Some of the managed beans being accessed are not even defined on the page in question. I have done some optimization based on comments related to multiple calls to getters, but I still have the issue that I have a very specialized (and expensive to initialize) bean that is getting called when I don't want it initialized. Any insight into why/what JSF calls might do something like this. I have a very complex page making use of JSTL, Tomahawk and standard JSF tags. I could include code, but its very complex and sensitive in nature.

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• Linq to SQL - design question.

  - by UshaP

  HI, Currently i have one big datacontex with 35 tables (i dragged all my DB tables to the designer). I must admit it is very comfortable cause i have ORM to my full DB and query with linq is easy and simple. My questions are: 1. Would you consider it bad design to have one datacontext with 35 tables or should i split it to logic units? 2. Is there any performance penalties for using such a big datacontext? Thanks, Pini.

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• C++ get method - returning by value or by reference

  - by HardCoder1986

  Hello! I've go a very simple question, but unfortunately I can't figure the answer myself. Suppose I've got some data structure that holds settings and acts like a settings map. I have a GetValue(const std::string& name) method, that returns the corresponding value. Now I'm trying to figure out - what kind of return-value approach would be better. The obvious one means making my method act like std::string GetValue(const std::string& name) and return a copy of the object and rely on RVO in performance meanings. The other one would mean making two methods std::string& GetValue(...) const std::string& GetValue(...) const which generally means duplicating code or using some evil constant casts to use one of these routines twice. #Q What would be your choice in this kind of situation and why?

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• What is the best platform/language for a 3D game in a web browser?

  - by CodeJustin.com

  I have enjoyed making 2D games in various langues (actionscript 3.0, java, python, others) but now I'm ready to move into 3D and to really get me amped up while learning 3D development I'm going to attempt to make a 3D multiplayer game (I already have server written in python). I'm looking for a platform that will run a 3D game well in the browser on low end computers with low end internet. What first came to mind was try Java or use flash/silver light with a 3D framework but I wanted to ask the good people of stackoverflow since performance is a big part of my needs and also good documentation is a plus since I'm just starting 3D development. (the programming language does not matter)

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• The case of the mysterious MySQL caching across restarts

  - by shanusmagnus

  I found a very slow MySQL query in my web app. The weird thing is that the query is only slow the first time it's executed, despite the fact that the query_cache is set to its default (query_cache_size 0) like so: mysql> show variables like 'query%'; +------------------------------+---------+ | Variable_name | Value | +------------------------------+---------+ | query_alloc_block_size | 8192 | | query_cache_limit | 1048576 | | query_cache_min_res_unit | 4096 | | query_cache_size | 0 | | query_cache_type | ON | | query_cache_wlock_invalidate | OFF | | query_prealloc_size | 8192 | +------------------------------+---------+ The even weirder thing is that this speedup persists even after the MySQL server has been stopped and restarted (I'm using OSX, and perform this restart using the system preferences pane.) The only way I can re-create the poor performance of the initial query is by rebooting the system. So my question is: how is this happening? Obviously some sort of caching at work, but where? And how does it persist across database restarts? This query is mediated through our web app, which comes via PHP/Apache, but there are no extra bells and whistles, and the curious caching also persists across Apache restarts. Help?

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• C++ Typing and OOP child classes

  - by Zack

  I'm a bit confused: If I have a base class A, and a class B which extends A, can a variable of the type A hold a value of the type B and vice versa? If yes, why? Aren't they completely different even if B is derived from A? How about type-safety? If this is possible, what things do I have to mind when taking use of this? How would this work out in terms of performance? Note: Sorry if I asked too many questions, just ignore them and just look out for those "marked" with the list decoration dot :) Also, this is not my homework. I'm a hobby programmer and have skills in scripting languages with OOP, yet I'm relatively new to OOP typing in C++.

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• Examples of both beautiful and ugly java code?

  - by tputkonen

  I would like to demonstrate how difficult it is for a layman to identify high quality code from flawed code. I'm thinking of doing this with the help of two java methods. Both of the methods should look like they do the same, pretty simple thing. However one of them should have several kind of flaws, for example: iteration with array off by one error string concatenations causing lots of objects to be created (as opposed to StringBuffer in the "good" code, which looks more complicated) possibly null pointer exception (but it should not be trivial to spot) Those are just some examples, all kinds of other issues including bugs and performance related structures are highly appreciated. Methods should be around 10-20 lines of length, and the task they do should be something simple - preferably printing something in an iteration.

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• What is the best way to keep database data encrypted with user passwords?

  - by Dan Sosedoff

  Let's say an application has really specific data which belongs to a user, and nobody is supposed to see it except the owner. I use MySQL database with DataMapper ORM mapper. The application is written in Ruby on Sinatra. Application behavior: User signs up for an account. Creates username and password. Logs into his dashboard. Some fields in specific tables must be protected. Basically, I'm looking for auto-encryption for a model properties. Something like this: class Transaction include DataMapper::Resource property :id, Serial property :value, String, :length => 1024, :encrypted => true ... etc ... belongs_to :user end I assume that encryption/decryption on the fly will cause performance problems, but that's ok. At least if that works - I'm fine. Any ideas how to do this?

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• matrix = *((fxMatrix*)&d3dMatrix); //Evil?

  - by Xilliah

  I've been using matrix = *((fxMatrix*)&d3dMatrix); for quite a while. It worked fine until my screen turned black and received a bucket of frustration on my desk. fxMatrix contains 4 fxVectors. fxVector used to be 16 bytes, but now it was suddenly 20. This was because it inherited fxStreamable, which added the vTable. So one solution is of course just to not inherit fxStreamable, and leave a comment saying that it must always be 16 bytes and never more. Another solution would be to make conversion functions, and copy the matrix completely. This makes it more secure, but has an impact on the performance. I suppose this is the best idea. Another solution is to not convert at all, and stick to D3DXMATRIX, but this makes the engine inconsistent and I personally really dislike this idea. What is your opinion?

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• Indexing XMLType columns

  - by Chris

  Hello, I am working with a XMLType and currently experiencing significant performance issues and would like to incorporate indexing to the column type. Currently I am taking the approach of using the XMLTable() and XQuery functions to create a virtual table. I would like to use this Virtual Table to create a function based index on the table containing the XMLType, but I am receiving this error: Error report: SQL Error: ORA-00907: missing right parenthesis 00907. 00000 - "missing right parenthesis" *Cause: *Action: This is the index.. any assistance would be greatly appreciated. CREATE INDEX indx_medicinalproduct ON d.ProductName XMLTable('for $i at $a in /safetyreport/patient//drug for $j in $i/medicinalproduct return element r { $i/medicinalproduct }' PASSING s.safetyreport COLUMNS ProductName varchar2(70) PATH 'medicinalproduct') d;

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• Designing entire webpages as SVG files

  - by user1311390

  Disclaimer I realize that given the absurdity of the title, this sounds like a troll. However, it's a genuine question. My background involves OpenGL / x86 assembly. I've recently started learning web programming. I really like SVG + CSS, and was wondering -- why do people not design entire webpages in SVG? Context SVG provides beautiful primitive: quadratic + cubic bezier curves; lines + filling -- all as vector graphics SVG provides text SVG provides affine transformations Questions Are there examples of people designing entire websites as a giant SVG file? If not, what the limitations? Are there performance hits when using SVG primitives as opposed to divs/tables?

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• When we should use NSThreads in a cocoa Touch ?

  - by srikanth rongali

  I am writing a small game by using cocos2d. It is a shooting game. Player on one side and enemy on other side. To run the both actions of player shooting and enemy shooting do we should use threads ? Or can we do without using them. At present I am not using threads. But I can manage to do both actions of player and enemy at same time. Should I use threads compulsory good performance ? Or am I doing wrong without using threads ? Please help me from this confusion. Thank you.

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• hibernate distributed 2nd level cache options

  - by ishmeister

  Not really a question but I'm looking for comments/suggestions from anyone who has experiences using one or more of the following: EhCache with RMI EhCache with JGroups EhCache with Terracotta Gigaspaces Data Grid A bit of background: our applications is read only for the most part but there is some user data that is read-write and some that is only written (and can also be reasonably inaccurate). In addition, it would be nice to have tools that enable us to flush and fill the cache at intervals or by admin intervention. Regarding the first option - are there any concerns about the overhead of RMI and performance of Java serialization?

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• Is scala functional programming slower than traditional coding?

  - by Fred Haslam

  In one of my first attempts to create functional code, I ran into a performance issue. I started with a common task - multiply the elements of two arrays and sum up the results: var first:Array[Float] ... var second:Array[Float] ... var sum=0f; for(ix<-0 until first.length) sum += first(ix) * second(ix); Here is how I reformed the work: sum = first.zip(second).map{ case (a,b) => a*b }.reduceLeft(_+_) When I benchmarked the two approaches, the second method takes 40 times as long to complete! Why does the second method take so much longer? How can I reform the work to be both speed efficient and use functional programming style?

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• C#. Struct design. Why 16 byte is recommended size?

  - by maxima120

  I read Cwalina book (recommendations on development and design of .NET apps). He says that good designed struct has to be less than 16 bytes in size (for performance purpose). My questions is - why exactly is this? And (more important) can I have larger struct with same efficiency if I run my .NET 3.5 (soon to be .NET 4.0) 64-bit application on i7 under Win7 x64 (is this limitation CPU / OS based)? Just to stress again - I need as efficient struct as it is possible. I try to keep it in stack all the time, the application is heavily multi-threaded and runs on sub-millisecond intervals, the current size of the struct is 64 byte.

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• iPad: How can I implement a scrolling timeline using a static image?

  - by BeachRunnerJoe

  I'm diving into iOS development and I'm building a simple timeline app using a static timeline image that I already have. The timeline image won't fit on the screen. The width of the image is about five times the width of the iPad screen, so I have to allow the user to scroll the image horizontally. Here's a mockup... For each item on the timeline, the user can tap it to receive a description at the bottom of the screen. My questions are... I was planning to use a UIScrollView with a PageControl at the bottom. Can a UIScrollView hold a single view that holds the entire timeline image or do I have to break the the timeline image up into multiple views? Are there any performance issues I need to consider when implementing this with a UIScrolLView, using a static image? Are there other approaches to implementing this scrollable timeline that I should consider other than using a UIScrollView? Thanks so much in advance for your wisdom!

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• How to pass a reference to a string in JavaScript?

  - by ijjo

  Maybe a closure is my solution? Not exactly sure how to pull it off though. The code is set up like so: var globalVar = ''; var globalVar2 = ''; function func() { if (condition) func2(globalVar) else func2(globalVar2) } In func2() I cache some HTML in a main container into the appropriate global variable that I pass to it. Basically I have a main container that holds different pages depending on what tab they choose. For performance I want to cache the page into global vars so I need to know what tab is active to figure out which global var to assign the HTML to.

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• C# asp.net MVC: When to update LastActivityDate?

  - by Oskar Kjellin

  I'm using asp.net mvc and creating a public website. I need to keep track of users that are online. I see that the standard way in asp.net of doing this is to keep track of LastActivityDate. My question is when should I update this? If I update it every time the users clicks somewhere, I will feel a performance draw back. However if I do not do that, people that only surf arround will be listed as offline. What is the best way to do this in asp.net MVC?

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• Which is more efficent PHP: array_intersect() OR array_intersect_key()

  - by Jordan Rutty

  Is it more efficient to use the key intersect or the value intersect if both key and value have the same contents for example: Array ( [743] => 743 [744] => 744 [745] => 745 [746] => 746 [747] => 747 [748] => 748 ) Is there any difference in performance in using one or the other with the same values. Similar to the difference of using double or single quotes?

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• Restricting deletion with NHibernate

  - by FrontSvin

  I'm using NHibernate (fluent) to access an old third-party database with a bunch of tables, that are not related in any explicit way. That is a child tables does have parentID columns which contains the primary key of the parent table, but there are no foreign key relations ensuring these relations. Ideally I would like to add some foreign keys, but cannot touch the database schema. My application works fine, but I would really like impose a referential integrity rule that would prohibit deletion of parent objects if they have children, e.i. something similar 'ON DELETE RESTRICT' but maintained by NHibernate. Any ideas on how to approach this would be appreciated. Should I look into the OnDelete() method on the IInterceptor interface, or are there other ways to solve this? Of course any solution will come with a performance penalty, but I can live with that.

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• Separate one-off code paths

  - by DeadMG

  I'm implementing an application with different code paths that shall be chosen once at startup and then fixed forevermore for that execution- for example, choosing D3D11 or D3D9 rendering path. Obviously I don't want to duplicate all my other code. Is run-time inheritance (no virtual inheritance) a fair solution? I don't want to waste a bunch of performance making virtual lookups when the type was fixed long ago. Not just that, but it makes me nervous that the functions can't be inlined and whether or not it affects RVO and NRVO and such. Am I just being over-concerned about this?

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• SQL Server, fetching data from multiple joined tables. Why is slow?

  - by user562192

  I have problem with performance when retrieving data from SQL Server. My sql query looks something like this: SELECT table_1.id, table_1.value, table_2.id, table_2.value,..., table_20.id, table_20.value From table_1 INNER JOIN table_2 ON table_1.id = table_2.table_1_id INNER JOIN table_3 ON table_2.id = table_3.table_2_id... WHERE table_1.row_number BETWEEN 1 AND 20 So, I am fetching 20 results. This query takes about 5 seconds to execute. When I select only table_1.id, it returns results instantly. Because of that, I guess that problem is not in JOINs, it is in retrieving data from multiple tables. Any suggestions how I would speed up this query?

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• Selecting a value from multiple dictionaries inside an enumeration

  - by johaanfaust

  If I have an enumeration of dictionaries IEnumerable<IDictionary<string, float>> enumeration can I perform a Linq query on it so that I can select by a value from each dictionary in the enumeration using the same key? I can do this in a loop: float f; foreach (var dictionary in enumeration) { if (dictionary.TryGetValue("some key", out f)) { Console.WriteLine(f); } } (The eventual plan is to compare the performance of the query verses the equivalent nested looping statements (the enumeration itself is formed from either another query or an equivalent set of loops).)

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• Python 3 order of testing undetermined

  - by user578598

  string='a' p=0 while (p <len(string)) & (string[p]!='c') : p +=1 print ('the end but the process already died ') while (p <1) & (string[p]!='c') : IndexError: string index out of range I want to test a condition up to the end of a string (example string length=1) why are both parts of the and executed is the condition is already false! as long as p < len(string). the second part does not even need executing. if it does a lot of performance can be lost

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• Making simple tabs in android

  - by user2910566

  I am new to Android. I am making a tab Activity that has 3 tabs in it. . I came across reading some interesting articles that tab can be made in three ways:: Regular TabHost Using simple Fragments Using Action Bar Sherlock I have a set of questions Which is a better choice & why ? Which gives more flexibility, efficiency & performance ? Which would be the preferd choice in case of requirement changes happen in future ? My research indicate :: ActionBarsherlock is better ! Is there something better than this ? If so what is it ?

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