Questions related to improving application performance, this can be range from selection software architecture to selection of algorithms.

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0
votes
2answers
107 views

Whats a good structure to save and retrieve locations of images?

I got a java-ee application, where I collect informations about movies. Im my backend I provide data like the name, description, genre and a random uuid. I also got lots of related files, which are ...
6
votes
4answers
458 views

Are there technical limitations or language features that prevent my Python script from being as fast as an equivalent C++ program?

I'm a long-time Python user. A few years ago, I started learning C++ to see what it could offer in terms of speed. During this time, I would continue to use Python as a tool for prototyping. This, it ...
2
votes
3answers
237 views

Will object reuse optimize this often-called function?

Suppose I have a function that I need to call a lot, maybe a few thousand times on every mouse down or mouse move. It uses an instance of a function (class), called Transform: function func1(a, b, c) ...
1
vote
1answer
377 views

How can we perform automated performance testing? [on hold]

How can we effectively manage our performance scripts? When the new codes checked in, the performance scripts should run under certain loads to measure how fast/slow it is. So, any ideas for ...
2
votes
0answers
138 views

How to evaluate JNI approaches with Java and Fortran? [on hold]

Right now we've got about 150k lines of Java broken into two major parts. The first contains an implementation of the algorithms we're hoping to redo in Fortran, and the second has a good chunk of GUI ...
0
votes
2answers
50 views

Static and dynamic data : should I use different databases?

Say I am building a website that uses two different types of data : Static : information that will hardly change, like movie awards or world countries names (I want fast access so no external API) ...
1
vote
2answers
91 views

Should I group all of my .js files into one large bundle?

One of the difficulties I'm running into with my current project is that the previous developer spaghetti'd the javascript code in lots of different files. We have modal dialogs that are reused in ...
0
votes
0answers
18 views

Does it make sense to build ATLAS from source on a cloud machine? [migrated]

ATLAS is an extremely popular linear algebra library. When you install ATLAS from source, it tries to automatically tune a number of parameters to give you the fastest code. Does it make sense to do ...
0
votes
1answer
126 views

Good approach for hundreds of comsumers and big files

I have several files (nearly 1GB each) with data. Data is a string line. I need to process each of these files with several hundreds of consumers. Each of these consumers does some processing that ...
1
vote
1answer
155 views

Why did Shannon's outguessing machine beat Hagelbarger's?

I'm reading "Rock Breaks Scissors", which describes two "outguessing machines" built at Bell Labs that try to exploit human non-randomness in the game of matching pennies. There was an outguessing ...
0
votes
0answers
23 views

Inserting a hyphen when string changes from alpha to numeric [migrated]

Given a random alphanumeric string (A-Z0-9) between 1 to 10 characters long, I'd like to insert a hyphen when it changes from alpha to numeric, or numeric to alpha. I have something that works now, ...
-1
votes
1answer
56 views

Huge long addition overhead compared to Native call?

A run a simple test JDK 1.7.0_45 (Windows 7, 64bit): Test 1: long start = System.nanoTime(); for (int i=0; i < 1000000; i++) { System.currentTimeMillis(); } elapsed = ...
0
votes
4answers
220 views

What is the “1620's multiplication operation”?

I was stumbling through Wikipedia when I came across the entry for FLOPS, specifically the table in this section. The first entry is for a computer from 1961, the comment on the right reads The ...
3
votes
1answer
351 views

Hadoop and Object Reuse, Why?

In Hadoop, objects passed to reducers are reused. This is extremely surprising and hard to track down if you're not expecting it. Furthermore, the original tracker for this "feature" doesn't offer any ...
-4
votes
6answers
2k views

Is having two conditions in an IF statement faster than having two separate IF statements?

I just wonder if having two conditions in an IF statement executes faster than having it separated into two like these: Single Statement, two conditions if ( (conditionA == true) && ...
1
vote
4answers
121 views

Track performance numbers

I have a (large) software project in a git repository. There is a benchmark suite that spits out lots of numbers (time per benchmark, allocations done per benchmark) I’d like to track. What is the ...
0
votes
0answers
14 views

Defining property and find substitution for copy function of python in cython

I want to cythonize a code in python to speed up the code. In the following you can see my attempt to make my python class understandable for cython: import numpy as np cimport numpy as np ctypedef ...
3
votes
2answers
242 views

What's a good simple way to combat the n+1 problem?

I'm trying to better understand performance in PHP. One issue I'm thinking about is the n+1 problem. By n+1 I mean something like this: $posts = Posts::getPosts(); foreach($posts as $post) { ...
3
votes
1answer
186 views

Why does Haskell's built in max function run faster than mine?

I noticed that for some reason, Haskell's built in max function (which returns the greatest of two numbers) runs much faster than the one I wrote, even though they are essentially identical. From ...
5
votes
1answer
344 views

Why use Android Fragments?

I have read the documentation and some other questions' threads about this topic and I don't really feel convinced; I don't see clearly the limits of use of this technique. Fragments are now seen as ...
1
vote
1answer
391 views

Is there a module for writing low level code on Python?

Can you manipulate bits and memory directly using Python? If yes, wouldn't that be a best option to dealing with performance-critical spots than C bindings?
3
votes
3answers
205 views

Data Oriented Design - impractical with more than 1-2 structure “members”?

The usual example of Data Oriented Design is with the Ball structure: struct Ball { float Radius; float XYZ[3]; }; and then they make some algorithm that iterates a std::vector<Ball> ...
17
votes
4answers
554 views

How bad is it calling println() often than concatenating strings together and calling it once?

I know output to the console is a costly operation. In the interest of code readability sometimes it is nice to call a function to output text twice, rather than having a long string of text as an ...
4
votes
1answer
412 views

In Java, why use bit hacks when non-bitwise technique it is more readable?

Is there any legitimate use for bit manipulation hacks in higher-level languages such as Java? I can see them being useful in speed-sensitive low-level and computation-intensive programs, e.g. ...
25
votes
9answers
2k views

Is template “metaprogramming” in Java a good idea?

There is a source file in a rather large project with several functions that are extremely performance-sensitive (called millions of times per second). In fact, the previous maintainer decided to ...
-1
votes
1answer
75 views

get all the combination of a given set of numbers [duplicate]

I m trying to get the possible combinations of a given set of numbers say for example 123 The possible combinations would be 123 132 213 231 312 321 For this i have written a code as below - ...
23
votes
4answers
4k views

How to significantly improve Java performance?

The team over at LMAX have a presentation about how they were able to do 100k TPS at less than 1 ms of latency. They have backed up that presentation with a blog, technical paper (PDF) and the ...
0
votes
1answer
150 views

Using JDBC to asynchronously read large Oracle table

What strategies can be used to read every row in a large Oracle table, only once, but as fast as possible with JDBC & Java ? Consider that each row has non-trivial amounts of data (30 columns, ...
1
vote
1answer
79 views

In general: guard pages or heap checks? [closed]

I would like to know the advantages and disadvantages of using guard pages with bump-pointer allocation versus heap checks with bump-pointer allocation, including performance as a consideration. In a ...
0
votes
1answer
112 views

Power of 2 and performance in SQL Server

Many mathematical operation (such as division, multiplication, etc.) are supposed to be computed faster when dealing with power of two numbers (C++, C#?, ...) For instance 15 * 256 = 0x0e right ...
11
votes
4answers
308 views

Database design - Store state or compute state every time?

Let's say I have a relational database application and a "user" object and a "message" object. Now I want to show the number of unread messages to this user. What's the best way to archive this? Do I ...
0
votes
2answers
111 views

Is there a downside to using AggressiveInlining on simple properties?

I bet I could answer that myself if I knew more about tools to analyze how C#/JIT behaves but since I don't, please bear with me asking. I have simple code like this : private SqlMetaData[] ...
4
votes
5answers
1k views

Structuring database for multi-object “activity” and “following” functionalities

I am working on a web application which operate with different types of objects such as user, profiles, pages etc. All objects have unique object_id. When objects interact it may produce "activity", ...
-2
votes
1answer
91 views

What is the best way to get a method name in runtime?

Here is a little background of my problem: I implemented a singleton logger class which is being called from several projects. I want to log the name of the class as well as the name of the method ...
99
votes
11answers
19k views

Should we avoid object creation in Java?

I was told by a colleague that in Java object creation is the most expensive operation you could perform. So I can only conclude to create as few objects as possible. This seems somewhat to defeat ...
15
votes
1answer
9k views

What is the difference between btree and rtree indexing?

I've noticed on MySQLWorkbench that you can choose how to store your indexes before forward engineering your design. The storage types are: BTREE RTREE HASH Researching this, I found some ...
7
votes
5answers
996 views

Why did the team at LMAX use Java and design the architecture to avoid GC at all cost?

Why did the team at LMAX design the LMAX Disruptor in Java but all their design points to minimizing GC use? If one does not want to have GC run then why use a garbage collected language? Their ...
3
votes
1answer
3k views

Magic square check for N×N matrix with minimum complexity

Is there any algorithm that works better than O(n²) to verify whether a square matrix is a magic one (e.g. such as sum of all the rows, cols and diagonally are equal to each other)? I did see someone ...
1
vote
2answers
78 views

Which is more expensive multiple conditional branches or multiple relational expression in a single condition?

Which is more expensive in terms of processing costs if ( x < 20 && z == "M") { // statements 3 } if ( x >= 20 && w && x <= 65) { // statements 1 } if( x ...
2
votes
2answers
116 views

How faster could a dedicated chip do sequential squaring modulo operations to break a time crypto capsule?

I'm facing a very real problem and, sadly, I cannot find the answer on my own: I'm hitting my limit as a programmer because my hardware knowledge is not sufficiently advanced at all. It's an issue ...
7
votes
5answers
2k views

Improving performance for grepping over a huge file

I have FILE_A which has over 300,000 lines and FILE_B which has over 30 million lines. I created a Bash script that greps each line in FILE_A over in FILE_B and writes the result of the grep to a new ...
16
votes
12answers
6k views

Compilable modern alternatives to C/C++ [closed]

I am considering writing a new software product. Performance will be critical, so I am wary of using an interpreted or language or one that uses a emulation layer (read java). Which leads me to ...
1
vote
2answers
182 views

Polling vs events pros and cons in JavaScript

I'm bit of a novice to JavaScript so I've been wondering on positive and negative sides of using polling compared to using events in JavaScript? When does one use one or the other? By polling I ...
3
votes
1answer
347 views

Specifically for JS, CSS, HTML: what is the difference between optimization, compression, minification, tidying, concatenation?

When we talk about source code and the file which contains the code like CSS, HTML, JavaScript and we also talk about performance of a web site or application, what is the differences between these ...
0
votes
2answers
102 views

How should I create object after database insert PHP

I have just been working on a new project and doing things the same way I have for years now. However for the first time, I am constantly thinking about scalability and performance of both the ...
0
votes
2answers
200 views

foreach in list or foreach in list.where [duplicate]

I don't know what to call this question. This is my example: foreach (var item in lstItem.Where(item => stock.ItemCode == item.ItemCode)) { stock.ItemName = item.ItemName; ...
21
votes
7answers
3k views

Writing in C for Performance? [closed]

I know I have quite frequently heard that C typically has a performance advantage over C++. I didn't really think anything else of it until I realized that MSVC doesn't even seem to support the newest ...
0
votes
3answers
214 views

comparison of floating point numbers vs. comparsion of Integers in C [closed]

Does comparison of floating point numbers takes (considerably) longer time than comparison of Integers in C? I just wrote a C program of heap sort to sort floating point numbers. I am on ubuntu ...
1
vote
1answer
193 views

alternate approach of binary serialization/de-serialization

Is it possible to convert a list of object directly to byte[] (and vice versa) to gain performance (by avoiding serialization/de-serialization)? What I have in mind is that a list is somewhere in ...
1
vote
3answers
454 views

Is there a performance difference between ++x over x++? [duplicate]

Is there a performance difference between using ++x over x++ increment operators? I've see developers use ++x in loops where I would normally write x++ out of habit. For example; for(int x=0; x ...