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• NoSQL for concurrent reads/writes

  - by Mickael Marrache

  After getting some performance issues for an application using a MySQL database, I'm thinking of using NoSQL solutions. My architecture is as follows: One application receives messages from the network at a high throughput (i.e. 50000 messages/sec). Each message is stored in the DB, so it's important for the write rate to be as fast as the arrival rate. Then, I also have some PHP pages that accesses the DB to get the data stored by the other application. It's important for me that the retrieved data is as relevant as possible (i.e. not old data, let's say not more than 5 seconds old). Also, the data is not critical, so I don't need any security mechanism to avoid losing the data. I see there are a lot of NoSQL solutions, but I don't know if they are all relevant. Could you please provide me some directions. Thanks

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• How taxing would a game map grid be to a web browser?

  - by Vilx-

  Suppose we're making a strategy game (think Civilization) in a web browser. The game has a visible map portion - say 30x30 squares. Each square is 30x30px and has several overlaid images - the terrain, resources, units, roads, etc. The classical way of drawing this would be with a huge <table> where each cell would contain absolutely positioned images. It would probably be rendered in Javascript to reduce traffic. But it's still several thousand images and a huge table. Can the browser take it? Will the performance not drop below any acceptable limits? Alternatively I could keep a pre-rendered map image with as many overlays as possible, but that would be more work, I think.

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• JQuery Optimization: Is there any way to speed up the rendering of the FlexSelect control?

  - by Sephrial

  Greetings, I am new to jQuery, and I have a performance problem with the FlexSelect control where it takes about 5 seconds to render the dropdown control (in the renderDropdown() function). The dropdown list contains about 5000 element. I believe all the runtime is attributed to the following block of code: var list = this.dropdownList.html(""); $.each(this.results, function() { list.append($("<li/>").html(this.name)); }); Question: Are there any alternatives that would build this list of elements in a more inefficient manner?

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• How do I ensure GUI responsiveness when using OpenCL on the display GPU?

  - by pauldoo

  In my relatively short time learning OpenCL I frequently see my application cause the operating system UI to become significantly less responsive (several seconds for a window to respond to a drag for example). I have encountered this problem on Windows Vista and Mac OS X both with NVidia GPUs. What can I do when using OpenCL on the same GPU as the display to ensure that my application does not significantly degrade the UI responsiveness like this? Also, can this be done without taking needless performance losses within my application? (Ie, if the user is not doing some UI intensive task then I would not expect my application to run any slower than it does now.) I understand that any answers will be very platform specific (where platform includes OS/GPU/driver combo).

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• Why does ElapsedTicks X 10 000 not equal ElapsedMilliseconds for .Net's Stopwatch?

  - by uriDium

  I am trying to performance test some code. I am using a stopwatch. When I output the number of milliseconds it always tells me 0 so I thought that I would try the number of ticks. I am seeing that the number of ticks is about 20 000 to 30 000. Looking at the MSDN at TimeSpan.TicksPerMillisecond it says that is 10 000 ticks per millisecond. In that case why are the elapsed milliseconds on my stopwatch not appearing as 2 or 3? What am I missing? I have even outputed the result on the same line. This is what I get. Time taken: 26856 ticks, 0 ms And it is constant.

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• How to speed up my websites (backoffices)

  - by jmpena

  Hello im developing some backends in ASP.NET 2.0 and i have put all the images in Cache, GZIPED my CSS, JS files and everything to speedup the load of each options. the performance its good and i have no problems with the clients but i want "MORE" fast loads and im looking for some recomendations. Is important to mention that those websites are using only in intranets so im thinking to implement my next projects using IFRAME for content that way (i think) the options will be loading faster because they not have to load the entire site. any help / recomendations? thanks in advance.

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• Are indexes good or bad for a large database?

  - by gmemon

  Hello All, I read on MySQL Performance Blog that when tables are large, it is better to scan full tables, instead of using indexes. I have a table with tens of millions of rows. When conducting queries, if I use no indexes, then queries are 24 times slower than with indexes. I know lot of things may cause this (e.g., are rows stored sequentially), but can you please give me some hints what might be happening? Or how I should start examining this issue? I want to understand when use of indexes is preferred and when it's not Thanks

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• Should i really use integer primary IDs [sql]

  - by arthurprs

  For example, i always generate an auto-increment field for the users table, but i also specifies an UNIQUE index on their usernames. There is situations that i first need to get the userId for a given username and then execute the desired query. Or use a JOIN in the desired query. It's 2 trips to the database or a JOIN vs. a varchar index The above is just an example There is a real performance benefit on INT over small VARCHAR indexes? Thanks in advance!

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• Stored procedure called from C# executes 6 times longer than from SQL Management studio

  - by Sergey Osypchuk

  I have search stored procedure which is my performance bottleneck. In order to get control about what is happened, I added logging for all parameters and also execution time in SP. I noticed, that when I call SP from MIcrosoft SQL server management Studio execution time is 1.3-1.6 seconds, but when i call it from C#, it takes 6-8 secods (!!!) Parameters | Time (ms) "tb *"TreeType:259Parents:212fL:13;14fV:0;lcid:2057min:0max:10sort:-1 | 6406 "tb *"TreeType:259Parents:212fL:13;14fV:0;lcid:2057min:0max:10sort:-1 | 1346 SP is called with LINQ. Login settings are same. SP uses full text search What could cause this?

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• Table per subclass inheritance relationship: How to query against the Parent class without loading a

  - by Arthur Ronald F D Garcia

  Suppose a Table per subclass inheritance relationship which can be described bellow (From wikibooks.org - see here) Notice Parent class is not abstract @Entity @Inheritance(strategy=InheritanceType.JOINED) public class Project { @Id private long id; // Other properties } @Entity @Table(name="LARGEPROJECT") public class LargeProject extends Project { private BigDecimal budget; } @Entity @Table(name="SMALLPROJECT") public class SmallProject extends Project { } I have a scenario where i just need to retrieve the Parent class. Because of performance issues, What should i do to run a HQL query in order to retrieve the Parent class and just the Parent class without loading any subclass ???

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• Faking a Single Address Space

  - by dsimcha

  I have a large scientific computing task that parallelizes very well with SMP, but at too fine grained a level to be easily parallelized via explicit message passing. I'd like to parallelize it across address spaces and physical machines. Is it feasible to create a scheduler that would parallelize already multithreaded code across multiple physical computers under the following conditions: The code is already multithreaded and can scale pretty well on SMP configurations. The fact that not all of the threads are running in the same address space or on the same physical machine must be transparent to the program, even if this comes at a significant performance penalty in some use cases. You may assume that all of the physical machines involved are running operating systems and CPU architectures that are binary compatible. Things like locks and atomic operations may be slow (having network latency to deal with and all) but must "just work".

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• Invisible JFrame/JTable how much faster ?

  - by chacko

  I have a swing app. with a jframe with lots of internal frames containing large JTable. Those jtables get updated continuously so there is lots of repainting going on. in some circumstances I can simply keep the JFrame invisible. (frame.setVisible(false)) I was wondering if anybody knows if I will gain something in terms of performance (something considerable or not) such as 50% gain or you would only get 2% gain... and maybe some sort of explaination on what to expect. thanks

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• PHP image resize on the fly vs storing resized images

  - by Pablo

  I'm building a image sharing site and would like to know the pros and cons of resizing images on the fly with php and having the resized images stored. Which is faster? Which is more reliable? how big is the gap between the two methods in speed and performance? Please note that either way the images go through a PHP script for statistics like views or if hotlinking is allow etc... so is not like it will be a direct link for images if i opt to store the resize images. I'll appreciated your comments or any helpful links on the subject, Thanks.

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• Alternatives to FastDateFormat for efficient date parsing?

  - by Tom Tucker

  Well aware of performance and thread issues with SimpleDateFormat, I decided to go with FastDateFormat, until I realized that FastDateFormat is for formatting only, no parsing! Is there an alternative to FastDateFormat, that is ready to use out of the box and much faster than SimpleDateFormat? I believe FastDateFormat is one of the faster ones, so anything that is about as fast would do. Just curious , any idea why FastDateFormat does not support parsing? Doesn't it seriously limit its use? Thanks! EDIT Holy crap, I just left a comment and that literally REMOVED a good answer! This appears a serious bug on stackoverflow!

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• How to find which method makes my iPhone app slow ?

  - by Stewart Hou

  Currently I am working on a production app. One function acts like the settings.app on iPhone. When the user click a cell of a tableView, as shown below http://www.penguintech.net/images/stackoverflow/1.png It will push another view, which includes a textfield to let user input something. However, on both simulator and device, after the app just loaded, the delay between clicking and showing the second view takes around 2 seconds. Then if user get back to previous view and click again, it will be no delay at all. To detect which method makes the delay, I put a NSLog() in every involved methods, but when I was inspecting the console while running the app, all NSLog() message showed in 0.1 seconds, and then still a delay on the app. Is there any other way to trace the performance footage of a app? The Instruments shows only CPU usage in Mac OS not in iPhone.

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• How can I write faster JavaScript?

  - by a paid nerd

  I'm writing an HTML5 canvas visualization. According to the Chrome Developer Tools profiler, 90% of the work is being done in (program), which I assume is the V8 interpreter at work calling functions and switching contexts and whatnot. Other than logic optimizations (e.g., only redrawing parts of the visualization that have changed), what can I do to optimize the CPU usage of my JavaScript? I'm willing to sacrifice some amount of readability and extensibility for performance. Is there a big list I'm missing because my Google skills suck? I have some ideas but I'm not sure if they're worth it: Limit function calls When possible, use arrays instead of objects and properties Use variables for math operation results as much as possible Cache common math operations such as Math.PI / 180 Use sin and cos approximation functions instead of Math.sin() and Math.cos() Reuse objects when passing around data instead of creating new ones Replace Math.abs() with ~~ Study jsperf.com until my eyes bleed Use a preprocessor on my JavaScript to do some of the above operations

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• Oracle SQL: Multiple Subqueries Unioned Without Running Original Query Multiple Times.

  - by Bob

  So I've got a very large database, and need to work on a subset ~1% of the data to dump into an excel spreadsheet to make a graph. Ideally, I could select out the subset of data and then run multiple select queries on that, which are then UNION'ed together. Is this even possible? I can't seem to find anyone else trying to do this and would improve the performance of my current query quite a bit. Right now I have something like this: SELECT ( SELECT ( SELECT( long list of requirements ) UNION SELECT( slightly different long list of requirements ) ) ) and it would be nice if i could group the commonalities of the two long requirements and have simple differences between the two select statements being unioned.

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• Should i use TabContainer for multiple pages?

  - by Tim

  I'm considering if it is a good idea to use an ASP.Net TabContainer-Control in the way that every TabPanel contains content of a different page. For example: Next i want to implement in my application is the masterdata management. Normally i would create one aspx page for every masterdata-table (f.e. Customer - MD_Customer.aspx). Then i would add a link into my Menu to this page. Now i'm thinking of creating one aspx page for all(Masterdata.aspx) with a Tabcontainer and an UpdatePanel for every type of Masterdata. The link it the menu could have an additional MDType as URL-Parameter. My main concerns are related to performance(one "page" for every TabPanel currently means 7 "pages" in one) and maintainability because of increasing complexity. Is it a good approach or a bad idea? Thanks

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• Making linq avoid using in memory filtering where possible

  - by linqmonkey

  Consider the these two LINQ2SQL data retrieval methods. The first creates a 'proper' SQL statement that filters the data, but requires passing the data context into the method. The second has a nicer syntax but loads the entire list of that accounts projects, then does in memory filtering. Is there any way to preserve the syntax of the second method but with the performance advantage of the first? public partial class Account { public IQueryable<Project> GetProjectsByYear(LinqDataContext context, int year) { return context.Projects.Where(p => p.AccountID==this.AccountID && p.Year==year).OrderBy(p => p.ProjectNo) } public IQueryable<Project> GetProjectsByYear(int year) { return this.Projects.Where(p => p.Year==year).OrderBy(p => p.ProjectNo).AsQueryable() } }

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• Why is this javascript function so slow on Firefox?

  - by macrael

  This function was adapted from the website: http://eriwen.com/javascript/measure-ems-for-layout/ function getEmSize(el) { var tempDiv = document.createElement("div"); tempDiv.style.height = "1em"; el.appendChild(tempDiv); var emSize = tempDiv.offsetHeight; el.removeChild(tempDiv); return emSize; } I am running this function as part of another function on window.resize, and it is causing performance problems on Firefox 3.6 that do not exist on current Safari or Chrome. Firefox's profiler says I'm spending the most time in this function and I'm curious as to why that is. Is there a way to get the em size in javascript without doing all this work? I would like to recalculate the size on resize incase the user has changed it.

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• Interpreted languages: The higher-level the faster?

  - by immersion

  I have designed around 5 experimental languages and interpreters for them so far, for education, as a hobby and for fun. One thing I noticed: The assembly-like language featuring only subroutines and conditional jumps as structures was much slower than the high-level language featuring if, while and so on. I developed them both simultaneously and both were interpreted languages. I wrote the interpreters in C++ and I tried to optimize the code-execution part to be as fast as possible. My hypothesis: In almost all cases, performance of interpreted languages rises with their level (high/low). Am I basically right with this? (If not, why?)

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• Does a servlet-based stack have significant overheads?

  - by John

  I don't know if it's simply because page-loads take a little time, or the way servlets have an abstraction framework above the 'bare metal' of HTTP, or just because of the "Enterprise" in Jave-EE, but in my head I have the notion that a servlet-based app is inherently adding overhead compared to a Java app which simply deals with sockets directly. Forget web-pages, imagine instead a Java server app where you send it a question over an HTTP request and it looks up an answer from memory and returns the answer in the response. You can easily write a Java socket-based app which does this, you can also do a servlet approach and get away from the "bare metal" of sockets. Is there any measurable performance impact to be expected implementing the same approach using Servlets rather than a custom socket-based HTTP listening app? And yes, I am hazy on the exact data sent in HTTP requests and I know it's a vague question. It's really about whether servlet implementations have lots of layers of indirection or anything else that would add up to a significant overhead per call, where by significant I mean maybe an additional 0.1s or more.

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• PHP 5.3 Namespaces should i use every PHP function with backslash?

  - by lhwparis

  Hi, im now using namespaces in PHP 5.3 now there is a fallback mechanism for functions which dont exist in the namespace. so php every time checks if the function exists in namespace and then tries to load it from global space. So what about all php internal functions? strstr for example? Should i now use every php internal function with a \ ? to avoid php first checking the namespace? is this fallback a huge performance drop? what do you think?

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• What GC parameters is a JVM running with?

  - by skaffman

  I'm still investigating issues I have with GC tuning (see prior question), which involves lots of reading and experimentation. Sun Java5+ JVMs attempt to automatically select the optimal GC strategy and parameters based on their environment, which is great, but I can't figure out how to query the running JVM to find out what those parameters are. Ideally, I'd like to see what values of the various GC-related -XX options are being used, as selected automatically by the VM. If I had that, I could have a baseline to begin tweaking. Anyone know to recover these values from a running VM?

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• How to make my WPF application as FAST as Outlook

  - by Raul Otaño

  The commons WPF applications take some time for loading medium complex views, once the view is loaded it works fine. For example in a Master - Detail view, if the Detail view is very complex and use different DataTemplates take some seconds (2-3 seconds) for load the view. When i open the Outlook application, for instance, it renders complex views and it is relative much more fast. Is there a way for increase the performance of my WPF application? Maybe a way for not loading the template's data every time that change the "master" item, and load it only one time in the app time live? i will appreciate any suggestion.

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