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  • Design for fastest page download

    - by mexxican
    I have a file with millions of URLs/IPs and have to write a program to download the pages really fast. The connection rate should be at least 6000/s and file download speed at least 2000 with avg. 15kb file size. The network bandwidth is 1 Gbps. My approach so far has been: Creating 600 socket threads with each having 60 sockets and using WSAEventSelect to wait for data to read. As soon as a file download is complete, add that memory address(of the downloaded file) to a pipeline( a simple vector ) and fire another request. When the total download is more than 50Mb among all socket threads, write all the files downloaded to the disk and free the memory. So far, this approach has been not very successful with the rate at which I could hit not shooting beyond 2900 connections/s and downloaded data rate even less. Can somebody suggest an alternative approach which could give me better stats. Also I am working windows server 2008 machine with 8 Gig of memory. Also, do we need to hack the kernel so as we could use more threads and memory. Currently I can create a max. of 1500 threads and memory usage not going beyond 2 gigs [ which technically should be much more as this is a 64-bit machine ]. And IOCP is out of question as I have no experience in that so far and have to fix this application today. Thanks Guys!

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  • Which messaging services can BlackBerry apps integrate with?

    - by humble coffee
    I'm in charge of having a BlackBerry app developed that translates the contents of a message from one language to another. So the aim would be to have a button at the bottom of a received message which says 'translate this'. I've heard that this kind of thing is possible using J2ME plus the native BlackBerry API. Can this be done for all kinds of messanging features on the Blackberry, or just some? ie I'm thinking SMS, email and BB messages. Secondly, given that the translation itself is done via a web request, I feel like this should be a fairly lightweight application. Would anyone care to hazard a guess how long it might take an experienced contractor to develop such an app?

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  • Easy way to convert c code to assembly?

    - by Bob
    Is there an easy way (like a free program) that can covert c/c++ code to x86 assembly? I know that any c compiler does something very similar and that I can just compile the c code and then disassemble the complied executable, but that's kind of an overkill, all I want is to convert a few lines of code. Does anyone know of some program that can do that?

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  • How can I write simulations in Erlang?

    - by rick
    Hi guys, I want to do some numerical stuff in Erlang like this: You've got an array with the following values: [2,3,4] In each iteration, you calculate 0.1 * [n-1] + 0.7 *[n] + 0.2 * [n+1] This becomes the new [n]. If n == 0 then [n-1] = 0. If [n] == length of array then [n] = 0. So I try an example: [2,3,4] calculations: 0.1 * 0 + 0.7 * 2 + 0.2 * 3 = 2 0.1 * 2 + 0.7 * 3 + 0.2 * 4 = 3.1 0.1 * 3 + 0.7 * 4 + 0.2 * 0 = 3.1 So [2,3,4] becomes to [2, 3.1, 3.1] after one iteration. I know how to write this in a non-functional language like C. But I have difficulties to imagine, how this could be done in Erlang. I found some tutorials on how you read a file to a list. So this is not the problem. How can I spawn different Erlang processes that each process has one element of the list? How can I do calculations by communicating with 'the neighbors', so that the neighbors know where their neigbors are generically, without specifying each? How can I collect the data into a list? Eventually, is it possible to solve that problem in Erlang at all? Thanks for your help.

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  • Challenging yourself as a programmer?

    - by Kevin
    We used to be a Coldfusion development shop before hopping over to PHP in 2008, now we primarily develop custom Drupal websites. I enjoyed going from CF to PHP, but I feel like I am getting a bit stale. I have been looking at different things like Ruby, Python, Obj C (iPhone). The problem is, there just isn't enough time in the day. What would be a fun new thing to learn that would refresh me a bit and challenge myself to learn more?

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  • Java.lang.NullPointerException when using retreived Image (Unless method is used statically!)

    - by Emdiesse
    Hi there, This has been doing my head in all day and I have finally decided to resort to asking for help! In my MIDLet I have an instance of the java class ImageFetcher called anImg. Also within my MIDLet I have a command that simply say's fetch, a CommandListener that when detects fetch was clicked runs the function below. This function should simply run public getImage() from the anImg instance of class ImageFetcher which returns an image and then appends/sets this Image onto the form on the display. (You may recognise the getImage() function from the Nokia JavaME Wiki!!!) Instead of any image being displayed this is written to the output terminal in netbeans: Msg: Java.lang.NullPointerException HOWEVER, If I change public getImage() to public static getImage() and replace anImg.getImage() with ImageFetcher.getImage() the image is successfully displayed!!! Thank you for your replies on this issue :) I look forward to going my hair back after this ordeal! FetchImageApp.java ... ... ... private doThis(){ try { Image im; if ((im = anImg.getImage()) != null) { ImageItem ii = new ImageItem(null, im, ImageItem.LAYOUT_DEFAULT, null); // If there is already an image, set (replace) it if (form.size() != 0) { form.set(0, ii); } else // Append the image to the empty form { form.append(ii); } } else { form.append("Unsuccessful download."); } // Display the form with the image display.setCurrent(form); } catch (Exception e) { System.err.println("Msg: " + e.toString()); } } ... ... ... ImageFetcher.java ... ... ... /*-------------------------------------------------- * Open connection and download png into a byte array. *-------------------------------------------------*/ public Image getImage() throws IOException { String url = "http://kenai.com/attachments/wiki_images/chessgame/java-duke-logo.png"; ContentConnection connection = (ContentConnection) Connector.open(url); // * There is a bug in MIDP 1.0.3 in which read() sometimes returns // an invalid length. To work around this, I have changed the // stream to DataInputStream and called readFully() instead of read() // InputStream iStrm = connection.openInputStream(); DataInputStream iStrm = connection.openDataInputStream(); ByteArrayOutputStream bStrm = null; Image im = null; try { // ContentConnection includes a length method byte imageData[]; int length = (int) connection.getLength(); if (length != -1) { imageData = new byte[length]; // Read the png into an array // iStrm.read(imageData); iStrm.readFully(imageData); } else // Length not available... { bStrm = new ByteArrayOutputStream(); int ch; while ((ch = iStrm.read()) != -1) { bStrm.write(ch); } imageData = bStrm.toByteArray(); bStrm.close(); } // Create the image from the byte array im = Image.createImage(imageData, 0, imageData.length); } finally { // Clean up if (iStrm != null) { iStrm.close(); } if (connection != null) { connection.close(); } if (bStrm != null) { bStrm.close(); } } return (im == null ? null : im); } ... ... ...

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  • Parallelism on two duo-core processor system

    - by Qin
    I wrote a Java program that draw the Mandelbrot image. To make it interesting, I divided the for loop that calculates the color of each pixel into 2 halves; each half will be executed as a thread thus parallelizing the task. On a two core one cpu system, the performance of using two thread approach vs just one main thread is nearly two fold. My question is on a two dual-core processor system, will the parallelized task be split among different processor instead of just utilize the two core on one processor? I suppose the former scenario will be slower than the latter one simply because the latency of communicating between 2 CPU over the motherboard wires. Any ideas? Thanks

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  • Can anyone tell me were I am making mistake in the snippet

    - by Solitaire
    public partial class Form1 : Form { [DllImport("coredll.dll")] static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong); const int GWL_WNDPROC = -4; public delegate int WindProc(IntPtr hWnd, uint msg, long Wparam, long lparam); public Form1() { InitializeComponent(); WindProc SampleProc = new WindProc (SubclassWndProc); SetWindowLong(this .Handle , GWL_WNDPROC, SampleProc.Method .MethodHandle.Value.ToInt32()); } public int SubclassWndProc(IntPtr hwnd, uint msg, long Wparam, long lparam) { return 1; } Here is the sample which i was trying to take the window procedure of a form, this is how i do in C++ i get the windwproc easlily if i try the same in C# .net 3.5 i am unable to get the window proc,, after calling SetWindowLong API application hangs and it pops up some dont send report... i have read this is the way to get the window proc.. please let me know were i am making mistake...

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  • Haskell: Why is it saying my function type is off?

    - by linkmaster03
    I wrote a little Haskell program to find the area of a triangle, primarily to practice custom types, but it keeps throwing the following error on compile: areafinder.hs:7:4: Couldn't match expected type 'Triangle' against inferred type 'm b' In a stmt of a 'do' expression: putStr "Base: " In the expression: do { putStr "Base: "; baseStr I'm not sure where 'm b' comes from, so I'm at a loss here. Why is it throwing this error, and what can I do to fix it? Here is my code: module Main where data Triangle = Triangle Double Double -- base, height getTriangle :: Triangle getTriangle = do putStr "Base: " baseStr Double calcTriangle (Triangle base height) = base * height main = putStrLn ("Area = " ++ show (calcTriangle getTriangle)) Thanks. :)

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  • Ability to Choose From Multiple SQLite DBs for Iphone Application

    - by Mark
    I am working on the design and implementation of an iPhone application ( a newbie, but I am getting the hang of it) where a person can download specific contact information about teachers based on their majors. The information is currently on different edu websites. And I have exported the information into SQLite databases. Is it possible to develop the application that when it is first initiated, it can give the user the option of which particular SQLite database they want for their application? Or if not, would it be better to merge all the DBs into one DB, and allow the user the option of downloading specific information from the SQLite db. I see that the db's can be downloaded into an app, but have yet to find a solution where there can be an option to download from different SQLite dbs. Thanks!

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  • HELP!! Implementing a search to match the specified author and displaying a book by the specified publisher

    - by Brian
    Hey guys! So i'm having problems with my assignment. I successfully got it to run multiple last names by the author, but now, I need to find all books by author, which means searching the collection for all books that match the specified author and I also need to find all books by publisher, which displays a list of books by the specified publisher. How would I implement this? Would I use string or vector? Any help will be much appreciated!

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  • Does a syntax for this exist? In any language?

    - by Michael
    It seems pretty common to me to have an argument, in a dynamically typed language that is either an Object or a key to lookup that object. For instance when I'm working with a database I might have a method getMyRelatedStuff(person) All I really need to lookup the related stuff is the id of the person so my method could look like this in python: def getMyRelatedStuff(person_or_id): id = person_or_id.id if isinstance(person,User) else person_or_id #do some lookup Or going the other direction: def someFileStuff(file_or_name): file = file_or_name if hasattr(file,'write') else open(file_or_name)

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  • std::out_of_range error?

    - by vette982
    I'm dealing with a file with a linked list of lines with each node looking like this: struct TextLine{ //The actual text string text; //The line number of the document int line_num; //A pointer to the next line TextLine * next; }; and I'm writing a function that adds spaces at the beginning of the lines found in the variable text, by calling functions like linelist_ptr->text.insert(0,1,'\t'); The program compiles, but when I run it I get this error: terminate called after throwing an instance of 'std::out_of_range' what(): basic_string::at Aborted Any ideas?

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  • How to see "anti if" movement and its gaol?

    - by Vijay Shanker
    I have a developer for last 3 years, have been using if-else or if-else if statements a lot in my programing habit. And today, I found This link. One obvious sample i put here public void doSomthing(String target, String object){ //validate requests if(target != null && target.trim().length() < 1){ //invalid request; } //further logic } Now, I have seen this sort of check all over the places, libraries. So, I wanted to have a discussion about the worthiness of such a movement. Please let me know your views.

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  • Scala, make my loop more functional

    - by Pengin
    I'm trying to reduce the extent to which I write Scala (2.8) like Java. Here's a simplification of a problem I came across. Can you suggest improvements on my solutions that are "more functional"? Transform the map val inputMap = mutable.LinkedHashMap(1->'a',2->'a',3->'b',4->'z',5->'c') by discarding any entries with value 'z' and indexing the characters as they are encountered First try var outputMap = new mutable.HashMap[Char,Int]() var counter = 0 for(kvp <- inputMap){ val character = kvp._2 if(character !='z' && !outputMap.contains(character)){ outputMap += (character -> counter) counter += 1 } } Second try (not much better, but uses an immutable map and a 'foreach') var outputMap = new immutable.HashMap[Char,Int]() var counter = 0 inputMap.foreach{ case(number,character) => { if(character !='z' && !outputMap.contains(character)){ outputMap2 += (character -> counter) counter += 1 } } }

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  • Low Throughput on Windows Named Pipe Over WAN

    - by MichaelB76
    I'm having problems with low performance using a Windows named pipe. The throughput drops off rapidly as the network latency increases. There is a roughly linear relationship between messages sent per second and round trip time. It seems that the client must ack each message before the server will send the next one. This leads to very poor performance, I can only send 5 (~100 byte) messages per second over a link with an RTT of 200 ms. The pipe is asynchronous, using multiple overlapped write operations (and multiple overlapped reads at the client end), but this is not improving throughput. Is it possible to send messages in parallel over a named pipe? The pipe is created using PIPE_TYPE_MESSAGE, would PIPE_READMODE_BYTE work better? Is there any other way I can improve performance? This is a deployed solution, so I can't simply replace the pipe with a socket connection (I've read that Windows named pipe aren't recommended for use over a WAN, and I'm wondering if this is why). I'd be grateful for any help with this matter.

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  • Directory name "cache" in IIS 5.

    - by Chuck Conway
    In IIS 5 one of the directories off the root has a leading underscore. All files under the directory are unreachable (404) from the browser. I have verified that the paths are correct. Other javascript files outside the directory comedown fine. Any thoughts? Example: http://fm74g4rndmu02.corp.com/_cache/softwarecommunity/api.js

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