performance

How expensive is a context switch? Is it better to implement a manual task switch than to rely on OS threads?

The title says it all. Imagine I have two (three, four, whatever) tasks that have to run in parallel. Now, the easy way to do this would be to create separate threads and forget about it. But on a plain old single-core CPU that would mean a lot of context switching - and we all know that context switching is big, bad, slow, and generally...

Lazy/deferred loading of a CollectionViewSource?

When you create a CollectionViewSource in the Resources section, is the set Source loaded when the resources are initalized (i.e. when the Resources holder is inited) or when data is bound? Is there a xamly way to make a CollectionViewSource lazy-load? deferred-load? explicit-load? ...

Database/NoSQL - Lowest latecy way to retreive the following data...

I have a real estate application and a "house" contains the following information: house: - house_id - address - city - state - zip - price - sqft - bedrooms - bathrooms - geo_latitude - geo_longitude I need to perform an EXTREMELY fast (low latency) retrieval of all homes within a geo-coordinate box. Something like the SQL below (...

Determining Best Table Structure for MySQL Performance

I'm working on a browser-based RPG for one of my websites, and right now I'm trying to determine the best way to organize my SQL tables for performance and maintenance. Here's my question: Does the number of columns in an SQL table affect the speed in which it can be queried? I am not a newbie when it comes to PHP or MySQL. I used to ...

.NET WebService IPC - Should it be done to minimise some expensive operations?

I'm looking at a few different approaches to a problem: Client requests work, some stuff gets done, and a result (ok/error) is returned. A .NET web service definitely seems like the way to go, my only issue is that the "stuff" will involve building up and tearing down a session for each request. Does abstracting the "stuff" out to an ap...

Would it be simply better to use the system's functions rather than use the language?

There are many scenarios where I've questioned PHP's performance with some of its functions, and whether I should build a complex class to handle specific things using its seemingly slow tools. For example, Complex regular expressions with sed and processing with awk would seemingly be exponential in performance rather than making PHP's...

How to get the FPS from a JavaFX scene?

I am currently writing a small graphical performance test benchmark for JavaFX. Thus, I need to get the current FPS at which the JavaFX scene is being refreshed. So far, I haven't found a solution how to accomplish this. Does anyone know if there is some kind of event that I could use in order to get the FPS? ...

What's holding up my PHP script?

We've got a PHP crawler running on our web server. When the crawler is running, there are no cpu, memory or network bandwidth spikes. Everything is normal. But our website (also PHP), hosted on the same server, stops responding. Basically the crawler blocks any other php script from running. What could be the problem? EDIT: ** fsockop...

Browser caching issue on a https site pressing f5

i am working on a website where i have content entry form. This form contains a tiny mce control. The control is composed of some 40-50 files. The testing reported that the entry form loads slow and evertime shows up 50 files loading to completely load the page. Is there a way i can decrease this time. I have taken help of browser cachin...

mysql datetime performance

Hi, since in mysql datetime field is represented as string (i'm not sure how it works internally), wouldn't be from performance point of view faster to store date as unix timestamp? I don't need to use any mysql native date functions, i'm going for performance of sorting and selecting data. if there was an index for that column, would ...

Can I improve performance by refactoring SQL commands into C# classes?

Currently, my entire website does updating from SQL parameterized queries. It works, we've had no problems with it, but it can occasionally be very slow. I was wondering if it makes sense to refactor some of these SQL commands into classes so that we would not have to hit the database so often. I understand hitting the database is gen...

Are closures in javascript recompiled

Let's say we have this code (forget about prototypes for a moment): function A(){ var foo = 1; this.method = function(){ return foo; } } var a = new A(); is the inner function recompiled each time the function A is run? Or is it better (and why) to do it like this: function method = function(){ return this.foo; } function A...

Do bit operations cause programs to run slower?

I'm dealing with a problem which needs to work with a lot of data. Currently its values are represented as an unsigned int. I know that real values do not exceed a limit of 1000. Questions I can use unsigned short to store it. An upside to this is that it'll use less storage space to store the value. Will performance suffer? If I dec...

Measuring debug vs release of ASP.NET applications

Which has the biggest impact? Building ASP.NET applications in release vs debug mode Setting <compilation debug="true"> in web.config Has anyone done any testing to get actual numbers about what the differences are, considering performance and memory usage? (Perhaps other metrics are useful as well?) For example, something like: E...

My program is spending most of its time in objc_msgSend. Does that mean that Objective-C has bad performance?

Hello Stackoverflow. I have written an application that has a number of custom views and generally draws a lot of lines and bitmaps. Since performance is somewhat critical for the application, I spent a good amount of time optimizing draw performance. Now, activity monitor tells me that my application is usually using about 12% CPU and...

Explanation for expires header

I have a joomla application working on Apache.To improve site performace we have written a .htaccess file to root of the application with setting a far future expires header to all the static content. As desired first time the files load in fresh with 200 status code. when again click on the same link many of the files are served directl...

What to have in mind when building a AJAX-based webapp

Hi everyone, We're in the first steps of what will be a AJAX-based webapp where information and generated HTML will be sent backwards and forwards with the help of JSON/POST techniques. We're able to get the data out quickly without putting to much load on the database with the help of a cache-layer that features memcached as well as d...

Performance analysis strategies

I am assigned to a performance-tuning-debugging-troubleshooting task. Scenario: a multi-application environment running on several networked machines using databases. OS is Unix, DB is Oracle. Business logic is implemented across applications using synchronous/asynchronous communication. Applications are multi-user with several hundred ...

Windows Azure Table Storage LINQ Operators

Currently Table Storage supports From, Where, Take, and First. Are there plans to support any of the other 29 operators? Are there architectural or design practices in regards to storage that one should follow in order to implement things like COUNT, SUM, GROUP BY, etc? If we have to code for these ourselves, how much of a performance...

Performance of looping over an Unboxed array in Haskell

First of all, it's great. However, I came across a situation where my benchmarks turned up weird results. I am new to Haskell, and this is first time I've gotten my hands dirty with mutable arrays and Monads. The code below is based on this example. I wrote a generic monadic for function that takes numbers and a step function rather...