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  • How can I tackle 'profoundly found elsewhere' syndrome (inverse of NIH)?

    - by Alistair Knock
    How can I encourage colleagues to embrace small-scale innovation within our team(s), in order to get things done quicker and to encourage skills development? (the term 'profoundly found elsewhere' comes from Wikipedia, although it is scarcely used anywhere else apart from a reference to Proctor & Gamble) I've worked in both environments where there is a strong opposition to software which hasn't been developed in-house (usually because there's a large community of developers), and more recently (with far fewer central developers) where off-the-shelf products are far more favoured for the usual reasons: maintenance, total cost over product lifecycle, risk management and so on. I think the off the shelf argument works in the majority of cases for the majority of users, even though as a developer the product never quite does what I'd like it to do. However, in some cases there are clear gaps where the market isn't able to provide specifically what we would need, or at least it isn't able to without charging astronomical consultancy rates for a bespoke solution. These can be small web applications which provide a short-term solution to a particular need in one specific department, or could be larger developments that have the potential to serve a wider audience, both across the organisation and into external markets. The problem is that while development of these applications would be incredibly cheap in terms of developer hours, and delivered very quickly without the need for glacial consultation, the proposal usually falls flat because of risk: 'Who'll maintain the project tracker that hasn't had any maintenance for the past 7 years while you're on holiday for 2 weeks?' 'What if one of our systems changes and the connector breaks?' 'How can you guarantee it's secure/better/faster/cheaper/holier than Company X's?' With one developer behind these little projects, the answers are invariably: 'Nobody, but...' 'It will break, just like any other application would...' 'I, uh...' How can I better answer these questions and encourage people to take a little risk in order to stimulate creativity and fast-paced, short-lifecycle development instead of using that 6 months to consult about what tender process we might use?

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  • Why does Tex/Latex not speed up in subsequent runs?

    - by Debilski
    I really wonder, why even recent systems of Tex/Latex do not use any caching to speed up later runs. Every time that I fix a single comma*, calling Latex costs me about the same amount of time, because it needs to load and convert every single picture file. (* I know that even changing a tiny comma could affect the whole structure but of course, a well-written cache format could see the impact of that. Also, there might be situations where 100% correctness is not needed as long as it’s fast.) Is there something in the language of Tex which makes this complicated or impossible to accomplish or is it just that in the original implementation of Tex, there was no need for this (because it would have been slow anyway on those large computers)? But then on the other hand, why doesn’t this annoy other people so much that they’ve started a fork which has some sort of caching (or transparent conversion of Tex files to a format which is faster to parse)? Is there anything I can do to speed up subsequent runs of Latex? Except from putting all the stuff into chapterXX.tex files and then commenting them out?

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  • Add two 32-bit integers in Assembler for use in VB6

    - by Emtucifor
    I would like to come up with the byte code in assembler (assembly?) for Windows machines to add two 32-bit longs and throw away the carry bit. I realize the "Windows machines" part is a little vague, but I'm assuming that the bytes for ADD are pretty much the same in all modern Intel instruction sets. I'm just trying to abuse VB a little and make some things faster. So... if the string "8A4C240833C0F6C1E075068B442404D3E0C20800" is the assembly code for SHL that can be "injected" into a VB6 program for a fast SHL operation expecting two Long parameters (we're ignoring here that 32-bit longs in VB6 are signed, just pretend they are unsigned), what is the hex string of bytes representing assembler instructions that will do the same thing to return the sum? The hex code above for SHL is, according to the author: mov eax, [esp+4] mov cl, [esp+8] shl eax, cl ret 8 I spit those bytes into a file and tried unassembling them in a windows command prompt using the old debug utility, but I figured out it's not working with the newer instruction set because it didn't like EAX when I tried assembling something but it was happy with AX. I know from comments in the source code that SHL EAX, CL is D3E0, but I don't have any reference to know what the bytes are for instruction ADD EAX, CL or I'd try it. I tried flat assembler and am not getting anything I can figure out how to use. I used it to assemble the original SHL code and got a very different result, not the same bytes. Help?

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  • WPF drawing performance with large numbers of geometries

    - by MyFaJoArCo
    Hello, I have problems with WPF drawing performance. There are a lot of small EllipseGeometry objects (1024 ellipses, for example), which are added to three separate GeometryGroups with different foreground brushes. After, I render it all on simple Image control. Code: DrawingGroup tmpDrawing = new DrawingGroup(); GeometryGroup onGroup = new GeometryGroup(); GeometryGroup offGroup = new GeometryGroup(); GeometryGroup disabledGroup = new GeometryGroup(); for (int x = 0; x < DisplayWidth; ++x) { for (int y = 0; y < DisplayHeight; ++y) { if (States[x, y] == true) onGroup.Children.Add(new EllipseGeometry(new Rect((double)x * EDGE, (double)y * EDGE, EDGE, EDGE))); else if (States[x, y] == false) offGroup.Children.Add(new EllipseGeometry(new Rect((double)x * EDGE, (double)y * EDGE, EDGE, EDGE))); else disabledGroup.Children.Add(new EllipseGeometry(new Rect((double)x * EDGE, (double)y * EDGE, EDGE, EDGE))); } } tmpDrawing.Children.Add(new GeometryDrawing(OnBrush, null, onGroup)); tmpDrawing.Children.Add(new GeometryDrawing(OffBrush, null, offGroup)); tmpDrawing.Children.Add(new GeometryDrawing(DisabledBrush, null, disabledGroup)); DisplayImage.Source = new DrawingImage(tmpDrawing); It works fine, but takes too much time - 0.5s on Core 2 Quad, 2s on Pentium 4. I need <0.1s everywhere. All Ellipses, how you can see, are equal. Background of control, where is my DisplayImage, is solid (black, for example), so we can use this fact. I tried to use 1024 Ellipse elements instead of Image with EllipseGeometries, and it was working much faster (~0.5s), but not enough. How to speed up it? Regards, Oleg Eremeev P.S. Sorry for my English.

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  • why MVC instead of good old asp.net? Still not grasping why I should go this route??

    - by RJ
    I know this question has been asked before and I read all the answers but they still don't give me the answers I am looking for. I need something concrete. I volunteered to give a presentation on MVC to other developers in our group which forces me to learn it. The big question everyone has is: "What can MVC bring to the table that we can't do in asp.net or MVC can do faster. I have just gone through Nerd Dinner and actually created a complete website that sort of mimics Nerd Dinner. But as great a job that Scott Guthrie did on it, there are big gaps that aren't answered such as, how do I throw a textbox on the listing page with a button and do a simple search. In asp.net, I would throw a textbox, button and grid on the page and bind it to a sproc and away I go. What is the equivalent in MVC. I guess I need a really good tutorial on how to use MVC without using Linq-to-Sql. I know I am sort of babbling on about this but it is a very serious question that still seems to go unanswered. On a side note, the View page of MVC brings back nightmares of classic asp with all the in-line code that we got away from way back when with code behind pages. Yes, MVC has Controller and Model classes which are great but I still don't like the classic asp tags in the html. Help me out here, I really like the concept of MVC and want it to be successful but I need more!

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  • High Runtime for Dictionary.Add for a large amount of items

    - by aaginor
    Hi folks, I have a C#-Application that stores data from a TextFile in a Dictionary-Object. The amount of data to be stored can be rather large, so it takes a lot of time inserting the entries. With many items in the Dictionary it gets even worse, because of the resizing of internal array, that stores the data for the Dictionary. So I initialized the Dictionary with the amount of items that will be added, but this has no impact on speed. Here is my function: private Dictionary<IdPair, Edge> AddEdgesToExistingNodes(HashSet<NodeConnection> connections) { Dictionary<IdPair, Edge> resultSet = new Dictionary<IdPair, Edge>(connections.Count); foreach (NodeConnection con in connections) { ... resultSet.Add(nodeIdPair, newEdge); } return resultSet; } In my tests, I insert ~300k items. I checked the running time with ANTS Performance Profiler and found, that the Average time for resultSet.Add(...) doesn't change when I initialize the Dictionary with the needed size. It is the same as when I initialize the Dictionary with new Dictionary(); (about 0.256 ms on average for each Add). This is definitely caused by the amount of data in the Dictionary (ALTHOUGH I initialized it with the desired size). For the first 20k items, the average time for Add is 0.03 ms for each item. Any idea, how to make the add-operation faster? Thanks in advance, Frank

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  • Performance: float to int cast and clipping result to range

    - by durandai
    I'm doing some audio processing with float. The result needs to be converted back to PCM samples, and I noticed that the cast from float to int is surprisingly expensive. Whats furthermore frustrating that I need to clip the result to the range of a short (-32768 to 32767). While I would normally instictively assume that this could be assured by simply casting float to short, this fails miserably in Java, since on the bytecode level it results in F2I followed by I2S. So instead of a simple: int sample = (short) flotVal; I needed to resort to this ugly sequence: int sample = (int) floatVal; if (sample > 32767) { sample = 32767; } else if (sample < -32768) { sample = -32768; } Is there a faster way to do this? (about ~6% of the total runtime seems to be spent on casting, while 6% seem to be not that much at first glance, its astounding when I consider that the processing part involves a good chunk of matrix multiplications and IDCT) EDIT The cast/clipping code above is (not surprisingly) in the body of a loop that reads float values from a float[] and puts them into a byte[]. I have a test suite that measures total runtime on several test cases (processing about 200MB of raw audio data). The 6% were concluded from the runtime difference when the cast assignment "int sample = (int) floatVal" was replaced by assigning the loop index to sample. EDIT @leopoldkot: I'm aware of the truncation in Java, as stated in the original question (F2I, I2S bytecode sequence). I only tried the cast to short because I assumed that Java had an F2S bytecode, which it unfortunately does not (comming originally from an 68K assembly background, where a simple "fmove.w FP0, D0" would have done exactly what I wanted).

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  • Effective Method to Manage and Search Through 100,000+ Objects Instantly? (C#)

    - by Kirk
    I'm writing a media player for enthusiasts with large collections (over 100,000 tracks) and one of my main goals is speed in search. I would like to allow the user to perform a Google-esque search of their entire music collection based on these factors: Song Path and File Name Items in ID3 Tag (Title, Artist, Album, etc.) Lyrics What is the best way for me to store this data and search through it? Currently I am storing each track in an object and iterating over an array of these objects checking each of their variables for string matches based on given search text. I've run into problems though where my search is not effective because it is always a phrase search and I'm not sure how to make it more fuzzy. Would an internal DB like SQLlite be faster than this? Any ideas on how I should structure this system? I also need playlist persistence, so that when they close the app and open the app their same playlist loads immediately. How should I store the playlist information so it can load quickly when the application starts? Currently I am JSON encoding the entire playlist, storing it in a text file, and reading it into the ListView at runtime, but it is getting sluggish over 20,000 tracks. Thanks!

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  • Should the code being tested compile to a DLL or an executable file?

    - by uriDium
    I have a solution with two projects. One for project for the production code and another project for the unit tests. I did this as per the suggestions I got here from SO. I noticed that in the Debug Folder that it includes the production code in executable form. I used NUnit to run the tests after removing the executable and they all fail trying to find the executable. So it definitely is trying to find it. I then did a quick read to find out which is better, a DLL or an executable. It seems that an DLL is much faster as they share memory space where communication between executables is slower. Unforunately our production code needs to be an exectuable. So the unit tests will be slightly slower. I am not too worried about that. But the project does rely on code written in another library which is also in executable format at the moment. Should the projects that expose some sort of SDK rather be compiled to an DLL and then the projects that use the SDK be compiled to executable?

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  • How to not cache a php file where a cachemanifest is beeing called?

    - by Volmar
    Hi, i'm building a iphone app with jqtouch and i use a cachemanifest to cache all the static files (images, css, javascript) to make it load faster. However the page uses php for the dynamic content and i don't want to cache that. So i'm generating the cachemanifest with this php-script(manifest.php): <?php header('Content-Type: text/cache-manifest'); echo "CACHE MANIFEST\n"; $hashes = ""; $lastFileWasDynamic = FALSE; $dir = new RecursiveDirectoryIterator("."); foreach(new RecursiveIteratorIterator($dir) as $file) { if ($file->IsFile() && $file != "./manifest.php" && substr($file->getFilename(), 0, 1) != ".") { if(preg_match('/.php$/', $file)) { if(!$lastFileWasDynamic) { echo "\n\nNETWORK:\n"; } $lastFileWasDynamic = TRUE; } else { if($lastFileWasDynamic) { echo "\n\nCACHE:\n"; $lastFileWasDynamic = FALSE; } } echo $file . "\n"; $hashes .= md5_file($file); } } echo "\nNETWORK:\nhttp://chart.apis.google.com/\n\n# Hash: " . md5($hashes) . "\n"; ?> This actually works really good except for one irritating thing: From what i read somewhere the file that calls the cachemanifest is automaticly included in the manifest and is beeing cached. Wich means that my start-page index.php, where i call the cachemanifest is beeing cached. This leads to very irritating problems. is there any way to deal with this or any smart workaround? The page is in the cachemanifest listed as NETWORK, but it looks like this is beeing overruled by the fact that the cachemanifest is called from the file.

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  • forward invocation, by hand vs magically?

    - by John Smith
    I have the following two class: //file FruitTree.h @interface FruitTree : NSObject { Fruit * f; Leaf * l; } @end //file FruitTree.m @implementation FruitTree //here I get the number of seeds from the object f @end //file Fruit @interface Fruit : NSObject { int seeds; } -(int) countfruitseeds; @end My question is at the point of how I request the number of seeds from f. I have two choices. Either: Since I know f I can explicitly call it, i.e. I implement the method -(int) countfruitseeds { return [f countfruitseeds]; } Or: I can just use forwardInvocation: - (NSMethodSignature *)methodSignatureForSelector:(SEL)selector { // does the delegate respond to this selector? if ([f respondsToSelector:selector]) return [f methodSignatureForSelector:selector]; else if ([l respondsToSelector:selector]) return [l methodSignatureForSelector:selector]; else return [super methodSignatureForSelector: selector]; } - (void)forwardInvocation:(NSInvocation *)invocation { [invocation invokeWithTarget:f]; } (Note this is only a toy example to ask my question. My real classes have lots of methods, which is why I am asking.) Which is the better/faster method?

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  • DSP - Filter sweep effect

    - by Trap
    I'm implementing a 'filter sweep' effect (I don't know if it's called like that). What I do is basically create a low-pass filter and make it 'move' along a certain frequency range. To calculate the filter cut-off frequency at a given moment I use a user-provided linear function, which yields values between 0 and 1. My first attempt was to directly map the values returned by the linear function to the range of frequencies, as in cf = freqRange * lf(x). Although it worked ok it looked as if the sweep ran much faster when moving through low frequencies and then slowed down during its way to the high frequency zone. I'm not sure why is this but I guess it's something to do with human hearing perceiving changes in frequency in a non-linear manner. My next attempt was to move the filter's cut-off frequency in a logarithmic way. It works much better now but I still feel that the filter doesn't move at a constant perceived speed through the range of frequencies. How should I divide the frequency space to obtain a constant perceived sweep speed? Thanks in advance.

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  • How to make std::vector's operator[] compile doing bounds checking in DEBUG but not in RELEASE

    - by Edison Gustavo Muenz
    I'm using Visual Studio 2008. I'm aware that std::vector has bounds checking with the at() function and has undefined behaviour if you try to access something using the operator [] incorrectly (out of range). I'm curious if it's possible to compile my program with the bounds checking. This way the operator[] would use the at() function and throw a std::out_of_range whenever something is out of bounds. The release mode would be compiled without bounds checking for operator[], so the performance doesn't degrade. I came into thinking about this because I'm migrating an app that was written using Borland C++ to Visual Studio and in a small part of the code I have this (with i=0, j=1): v[i][j]; //v is a std::vector<std::vector<int> > The size of the vector 'v' is [0][1] (so element 0 of the vector has only one element). This is undefined behaviour, I know, but Borland is returning 0 here, VS is crashing. I like the crash better than returning 0, so if I can get more 'crashes' by the std::out_of_range exception being thrown, the migration would be completed faster (so it would expose more bugs that Borland was hiding).

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  • I need to speed up a function. Should I use cython, ctypes, or something else?

    - by Peter Stewart
    I'm having a lot of fun learning Python by writing a genetic programming type of application. I've had some great advice from Torsten Marek, Paul Hankin and Alex Martelli on this site. The program has 4 main functions: generate (randomly) an expression tree. evaluate the fitness of the tree crossbreed mutate As all of generate, crossbreed and mutate call 'evaluate the fitness'. it is the busiest function and is the primary bottleneck speedwise. As is the nature of genetic algorithms, it has to search an immense solution space so the faster the better. I want to speed up each of these functions. I'll start with the fitness evaluator. My question is what is the best way to do this. I've been looking into cython, ctypes and 'linking and embedding'. They are all new to me and quite beyond me at the moment but I look forward to learning one and eventually all of them. The 'fitness function' needs to compare the value of the expression tree to the value of the target expression. So it will consist of a postfix evaluator which will read the tree in a postfix order. I have all the code in python. I need advice on which I should learn and use now: cython, ctypes or linking and embedding. Thank you.

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  • Will Learning C++ Help for Building Fast/No-Additional-Requirements Desktop Applications?

    - by vito
    Will learning C++ help me build native applications with good speed? Will it help me as a programmer, and what are the other benefits? The reason why I want to learn C++ is because I'm disappointed with the UI performances of applications built on top of JVM and .NET. They feel slow, and start slow too. Of course, a really bad programmer can create a slower and sluggish application using C++ too, but I'm not considering that case. One of my favorite Windows utility application is Launchy. And in the Readme.pdf file, the author of the program wrote this: 0.6 This is the first C++ release. As I became frustrated with C#’s large .NET framework requirements and users lack of desire to install it, I decided to switch back to the faster language. I totally agree with the author of Launchy about the .NET framework requirement or even a JRE requirement for desktop applications. Let alone the specific version of them. And some of the best and my favorite desktop applications don't need .NET or Java to run. They just run after installing. Are they mostly built using C++? Is C++ the only option for good and fast GUI based applications? And, I'm also very interested in hearing the other benefits of learning C++.

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  • java 6 web services share domain specific classes between server and client

    - by user173446
    Hi all, Context: Considering below defined Engine class being parameter of some webservice method. As we have both server and client in java we may have some benefits (???) in sharing Engine class between server and client ( i.e we may put in a common jar file to be added to both client and server classpath ) Some benefits would be : we keep specific operations like 'brushEngine' in same place build is faster as we do not need in our case to generate java code for client classes but to use them from the server build) if we later change server implementation for 'brushEngine' this is reflected automatically in client . Questions: How to share below detailed Engine class using java 6 tools ( i.e wsimport , wsgen etc )? Is there other tools for java that can achieve this sharing ? Is sharing a case that java 6 web services support is missing ? Can this case be reduced to other web service usage patterns? Thanks. Code: public class Engine { private String engineData; public String getData(){ return data; } public setData(String value){ this.data = value; } public void brushEngine(){ engineData = "BrushedEngine"+engineData; } }

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  • database structure

    - by jindalsyogesh
    I have a table named ActivityRecording. This table currently has 500,000 records. I need to add a lot of new inputs that relates to activityrecording table. The relation of activityrecording with these new input fields is 1 to 0,1. So, what's going to happen on screen is when user fills the ActivityRecording data, he will then be taken to a new page and this page will show a form based on the user's input (from a dropdown named service) in activityrecording. There will 6 different kinds of form (each form will have 7-8 inputs which includes textareas of size 5kb, textboxes and checkboxes). So, for one activityrecording user will fill one out of 6 forms. There are two ways I know (there could be more), I can design the data structure: Add all the inputs from all these 6 forms into the activityrecording table. So, columns belonging to 5 of these forms will be null in this table, only columns belonging to one of the forms will have values The other way would be add 6 new tables (one for each form) and add 6 foreign key columns to activityrecording table. So, out of 6 foreign keys, 5 will be null and one will actually point to a table Which approach is a better data structure design? Please take into consideration that number of rows in this table are 500,000 and are expected to grow at a faster rate now.

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  • Sql server query using function and view is slower

    - by Lieven Cardoen
    I have a table with a xml column named Data: CREATE TABLE [dbo].[Users]( [UserId] [int] IDENTITY(1,1) NOT NULL, [FirstName] [nvarchar](max) NOT NULL, [LastName] [nvarchar](max) NOT NULL, [Email] [nvarchar](250) NOT NULL, [Password] [nvarchar](max) NULL, [UserName] [nvarchar](250) NOT NULL, [LanguageId] [int] NOT NULL, [Data] [xml] NULL, [IsDeleted] [bit] NOT NULL,... In the Data column there's this xml <data> <RRN>...</RRN> <DateOfBirth>...</DateOfBirth> <Gender>...</Gender> </data> Now, executing this query: SELECT UserId FROM Users WHERE data.value('(/data/RRN)[1]', 'nvarchar(max)') = @RRN after clearing the cache takes (if I execute it a couple of times after each other) 910, 739, 630, 635, ... ms. Now, a db specialist told me that adding a function, a view and changing the query would make it much more faster to search a user with a given RRN. But, instead, these are the results when I execute with the changes from the db specialist: 2584, 2342, 2322, 2383, ... This is the added function: CREATE FUNCTION dbo.fn_Users_RRN(@data xml) RETURNS varchar(100) WITH SCHEMABINDING AS BEGIN RETURN @data.value('(/data/RRN)[1]', 'varchar(max)'); END; The added view: CREATE VIEW vwi_Users WITH SCHEMABINDING AS SELECT UserId, dbo.fn_Users_RRN(Data) AS RRN from dbo.Users Indexes: CREATE UNIQUE CLUSTERED INDEX cx_vwi_Users ON vwi_Users(UserId) CREATE NONCLUSTERED INDEX cx_vwi_Users__RRN ON vwi_Users(RRN) And then the changed query: SELECT UserId FROM Users WHERE dbo.fn_Users_RRN(Data) = '59021626919-61861855-S_FA1E11' Why is the solution with a function and a view going slower?

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  • How can you get the call tree with python profilers?

    - by Oliver
    I used to use a nice Apple profiler that is built into the System Monitor application. As long as your C++ code was compiled with debug information, you could sample your running application and it would print out an indented tree telling you what percent of the parent function's time was spent in this function (and the body vs. other function calls). For instance, if main called function_1 and function_2, function_2 calls function_3, and then main calls function_3: main (100%, 1% in function body): function_1 (9%, 9% in function body): function_2 (90%, 85% in function body): function_3 (100%, 100% in function body) function_3 (1%, 1% in function body) I would see this and think, "Something is taking a long time in the code in the body of function_2. If I want my program to be faster, that's where I should start." Does anyone know how I can most easily get this exact profiling output for a python program? I've seen people say to do this: import cProfile, pstats prof = cProfile.Profile() prof = prof.runctx("real_main(argv)", globals(), locals()) stats = pstats.Stats(prof) stats.sort_stats("time") # Or cumulative stats.print_stats(80) # 80 = how many to print but it's quite messy compared to that elegant call tree. Please let me know if you can easily do this, it would help quite a bit. Cheers!

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  • What image processing Library should I use

    - by Swippen
    I have been reading What is the best image manipulation library? And tried a few libraries and are now looking for inputs on what is the best for our need. I will start by describing our current setting and problems. We have a system that needs to resize and crop a large amount of images from big original images. We handle 50 000+ images every day on 2 powerfull servers. Today we use ImageGlue from WebSupergoo but we don't like it at all, it is slow and hangs the service now and then (Its in another unanswered stack overflow question). We have a threaded windows service that uses Microsoft ThreadPool to resize as much as possible on the 8 core machines. I have tried AForge and it went very well it was loads faster and never crashed or anything. But I had problems with quality on a few images. This due to what algorithms I used ofc so can be tweaked. But want to widen our eyes to see if thats the right way to go. so: It needs to be c# .net and run in a windows service. (Since we wont change the rest of the service only image handling) It needs to handle threaded environment well. We have a great need of it being fast since today its too slow. But we also want good quality and small filesize since the images are later displayed on webpage with loads of visitors and needs good quality. So we have a lot of demands on ability to get god quality at a fast pace, and also secondary keep filesizes lowered even if that can be adjusted with compression a bit. Any comments or suggestions on what library to use?

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  • Parallel.Foreach loop creating multiple db connections throws connection errors?

    - by shawn.mek
    Login failed. The login is from an untrusted domain and cannot be used with Windows authentication I wanted to get my code running in parallel, so I changed my foreach loop to a parallel foreach loop. It seemed simple enough. Each loop connects to the database, looks up some stuff, performs some logic, adds some stuff, closes the connection. But I get the above error? I'm using my local sql server and entity framework (each loop uses it's own context). Is there some problem with connecting multiple times using the same local login or something? How did I get around this? I have (before trying to covert to a parallel.foreach loop) split my list of objects that I am foreach looping through into four groups (separate csv files) and run four concurrent instances of my program (which ran faster overall than just one, thus the idea for parallel). So it seems connecting to the db shouldn't be a problem? Any ideas? EDIT: Here's before var gtgGenerator = new CustomGtgGenerator(); var connectionString = ConfigurationManager.ConnectionStrings["BioEntities"].ConnectionString; var allAccessionsFromObs = _GetAccessionListFromDataFiles(collectionId); ForEach(cloneIdAndAccessions in allAccessionsFromObs) DoWork(gtgGenerator, taxonId, organismId, cloneIdAndAccessions, connectionString)); after var gtgGenerator = new CustomGtgGenerator(); var connectionString = ConfigurationManager.ConnectionStrings["BioEntities"].ConnectionString; var allAccessionsFromObs = _GetAccessionListFromDataFiles(collectionId); Parallel.ForEach(allAccessionsFromObs, cloneIdAndAccessions => DoWork(gtgGenerator, taxonId, organismId, cloneIdAndAccessions, connectionString)); Inside the DoWork I use the BioEntities using (var bioEntities = new BioEntities(connectionString)) {...}

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  • How do I rewrite a for loop with a shared dependency using actors

    - by Thomas Rynne
    We have some code which needs to run faster. Its already profiled so we would like to make use of multiple threads. Usually I would setup an in memory queue, and have a number of threads taking jobs of the queue and calculating the results. For the shared data I would use a ConcurrentHashMap or similar. I don't really want to go down that route again. From what I have read using actors will result in cleaner code and if I use akka migrating to more than 1 jvm should be easier. Is that true? However, I don't know how to think in actors so I am not sure where to start. To give a better idea of the problem here is some sample code: case class Trade(price:Double, volume:Int, stock:String) { def value(priceCalculator:PriceCalculator) = (priceCalculator.priceFor(stock)-> price)*volume } class PriceCalculator { def priceFor(stock:String) = { Thread.sleep(20)//a slow operation which can be cached 50.0 } } object ValueTrades { def valueAll(trades:List[Trade], priceCalculator:PriceCalculator):List[(Trade,Double)] = { trades.map { trade => (trade,trade.value(priceCalculator)) } } def main(args:Array[String]) { val trades = List( Trade(30.5, 10, "Foo"), Trade(30.5, 20, "Foo") //usually much longer ) val priceCalculator = new PriceCalculator val values = valueAll(trades, priceCalculator) } } I'd appreciate it if someone with experience using actors could suggest how this would map on to actors.

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  • table design for storing large number of rows

    - by hyperboreean
    I am trying to store in a postgresql database some unique identifiers along with the site they have been seen on. I can't really decide which of the following 3 option to choose in order to be faster and easy maintainable. The table would have to provide the following information: the unique identifier which unfortunately it's text the sites on which that unique identifier has been seen The amount of data that would have to hold is rather large: there are around 22 millions unique identifiers that I know of. So I thought about the following designs of the table: id - integer identifier - text seen_on_site - an integer, foreign key to a sites table This approach would require around 22 mil multiplied by the number of sites. id - integer identifier - text seen_on_site_1 - boolean seen_on_site_2 - boolean ............ seen_on_site_n - boolean Hopefully the number of sites won't go past 10. This would require only the number of unique identifiers that I know of, that is around 20 millions, but it would make it hard to work with it from an ORM perspective. one table that would store only unique identifiers, like in: id - integer unique_identifier - text, one table that would store only sites, like in: id - integer site - text and one many to many relation, like: id - integer, unique_id - integer (fk to the table storing identifiers) site_id - integer (fk to sites table) another approach would be to have a table that stores unique identifiers for each site So, which one seems like a better approach to take on the long run?

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  • Algorithm for finding similar users through a join table

    - by Gdeglin
    I have an application where users can select a variety of interests from around 300 possible interests. Each selected interest is stored in a join table containing the columns user_id and interest_id. Typical users select around 50 interests out of the 300. I would like to build a system where users can find the top 20 users that have the most interests in common with them. Right now I am able to accomplish this using the following query: SELECT i2.user_id, count(i2.interest_id) AS count FROM interests_users as i1, interests_users as i2 WHERE i1.interest_id = i2.interest_id AND i1.user_id = 35 GROUP BY i2.user_id ORDER BY count DESC LIMIT 20; However, this query takes approximately 500 milliseconds to execute with 10,000 users and 500,000 rows in the join table. All indexes and database configuration settings have been tuned to the best of my ability. I have also tried avoiding the use of joins altogether using the following query: select user_id,count(interest_id) count from interests_users where interest_id in (13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,508) group by user_id order by count desc limit 20; But this one is even slower (~800 milliseconds). How could I best lower the time that I can gather this kind of data to below 100 milliseconds? I have considered putting this data into a graph database like Neo4j, but I am not sure if that is the easiest solution or if it would even be faster than what I am currently doing.

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  • capturing CMD batch file parameter list; write to file for later processing

    - by BobB
    I have written a batch file that is launched as a post processing utility by a program. The batch file reads ~24 parameters supplied by the calling program, stores them into variables, and then writes them to various text files. Since the max input variable in CMD is %9, it's necessary to use the 'shift' command to repeatedly read and store these individually to named variables. Because the program outputs several similar batch files, the result is opening several CMD windows sequentially, assigning variables and writing data files. This ties up the calling program for too long. It occurs to me that I could free up the calling program much faster if maybe there's a way to write a very simple batch file that can write all the command parameters to a text file, where I can process them later. Basically, just grab the parameter list, write it and done. Q: Is there some way to treat an entire series of parameter data as one big text string and write it to one big variable... and then echo the whole big thing to one text file? Then later read the string into %n variables when there's no program waiting to resume? Parameter list is something like 25 - 30 words, less than 200 characters. Sample parameter list: "First Name" "Lastname" "123 Steet Name Way" "Cityname" ST 12345 1004968 06/01/2010 "Firstname+Lastname" 101738 "On Account" 20.67 xy-1z 1 8.95 3.00 1.39 0 0 239 8.95 Items in quotes are processed as string variables. List is space delimited. Any suggestions?

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