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  • Java Parallel Programming

    - by user578524
    Dear All, I need to parallelize a CPU intensive Java application on my multicore desktop but I am not so comfortable with threads programming. I looked at Scala but this would imply learning a new language which is really time consuming. I also looked at Ateji PX Java parallel extensions which seem very easy to use but did not have a chance yet to evaluate it. Would anyone recommend it? Other suggestions welcome. Thanks in advance for your help Bill

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  • How to add more /dev/loop* devices on Fedora 19

    - by user219372
    How to add more /dev/loop* devices on Fedora 19? I do: # uname -r 3.11.2-201.fc19.x86_64 # lsmod |grep loop # ls /dev/loop* /dev/loop0 /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5 /dev/loop6 /dev/loop7 /dev/loop-control # modprobe loop max_loop=128 # ls /dev/loop* /dev/loop0 /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5 /dev/loop6 /dev/loop7 /dev/loop-control So nothing changes.

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  • Trying to create an infinite for loop that can stop using function doIt()

    - by JoeOzz
    Hey guys, I'm new to javascript and I'm doing a project for my final in class. I need to make it so this game engine I manipulated causes the generation button to go for an infinite loop. I also need to stop it using (Reset==1). Any help? Here's the code I have so far if that helps: function generation() { for(y2=0; y2<2500; y2++) { tempmapactual[y2]=mapactual[y2]; } for (g=0;g<2500;g++) { neighbours=0; for (h=0;h<8;h++) { if (g+coords[h]>0 && g+coords[h]<2499 && mapactual[g+coords[h]]=="white.gif") {neighbours=neighbours+1;} } if (neighbours>=4 || neighbours==1 || neighbours==0) {tempmapactual[g]="black.gif";} if (neighbours==3) {tempmapactual[g]="white.gif";} } for(y3=0; y3<2500; ++y3) { if (mapactual[y3]!=tempmapactual[y3]) { mapactual[y3]=tempmapactual[y3]; document.images[y3+offset].src=mapactual[y3]; } } } </script> <script> function doIt() { for (i=0; i<X; i++) { // This is where I have trouble. What part of generation() do I call? } if (Reset==1) break; // This will kill the loop instantly. } } </script> <script> window.onload(doIt($(X).value))); </script> <form> <input type="button" value="generate" onClick="generation();"> </form> <form> <input type="text"> </form> <form> <input type="button" value="Infinite Loop!" onclick="doIt();"> </form> <form> <input type="button" value="Reset" onclick="doIt();"> </form>

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  • Embarrassingly parallel workflow creates too many output files

    - by Hooked
    On a Linux cluster I run many (N > 10^6) independent computations. Each computation takes only a few minutes and the output is a handful of lines. When N was small I was able to store each result in a separate file to be parsed later. With large N however, I find that I am wasting storage space (for the file creation) and simple commands like ls require extra care due to internal limits of bash: -bash: /bin/ls: Argument list too long. Each computation is required to run through a qsub scheduling algorithm so I am unable to create a master program which simply aggregates the output data to a single file. The simple solution of appending to a single fails when two programs finish at the same time and interleave their output. I have no admin access to the cluster, so installing a system-wide database is not an option. How can I collate the output data from embarrassingly parallel computation before it gets unmanageable?

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  • Parallel processing via multithreading in Java

    - by Robz
    There are certain algorithms whose running time can decrease significantly when one divides up a task and gets each part done in parallel. One of these algorithms is merge sort, where a list is divided into infinitesimally smaller parts and then recombined in a sorted order. I decided to do an experiment to test whether or not I could I increase the speed of this sort by using multiple threads. I am running the following functions in Java on a Quad-Core Dell with Windows Vista. One function (the control case) is simply recursive: // x is an array of N elements in random order public int[] mergeSort(int[] x) { if (x.length == 1) return x; // Dividing the array in half int[] a = new int[x.length/2]; int[] b = new int[x.length/2+((x.length%2 == 1)?1:0)]; for(int i = 0; i < x.length/2; i++) a[i] = x[i]; for(int i = 0; i < x.length/2+((x.length%2 == 1)?1:0); i++) b[i] = x[i+x.length/2]; // Sending them off to continue being divided mergeSort(a); mergeSort(b); // Recombining the two arrays int ia = 0, ib = 0, i = 0; while(ia != a.length || ib != b.length) { if (ia == a.length) { x[i] = b[ib]; ib++; } else if (ib == b.length) { x[i] = a[ia]; ia++; } else if (a[ia] < b[ib]) { x[i] = a[ia]; ia++; } else { x[i] = b[ib]; ib++; } i++; } return x; } The other is in the 'run' function of a class that extends thread, and recursively creates two new threads each time it is called: public class Merger extends Thread { int[] x; boolean finished; public Merger(int[] x) { this.x = x; } public void run() { if (x.length == 1) { finished = true; return; } // Divide the array in half int[] a = new int[x.length/2]; int[] b = new int[x.length/2+((x.length%2 == 1)?1:0)]; for(int i = 0; i < x.length/2; i++) a[i] = x[i]; for(int i = 0; i < x.length/2+((x.length%2 == 1)?1:0); i++) b[i] = x[i+x.length/2]; // Begin two threads to continue to divide the array Merger ma = new Merger(a); ma.run(); Merger mb = new Merger(b); mb.run(); // Wait for the two other threads to finish while(!ma.finished || !mb.finished) ; // Recombine the two arrays int ia = 0, ib = 0, i = 0; while(ia != a.length || ib != b.length) { if (ia == a.length) { x[i] = b[ib]; ib++; } else if (ib == b.length) { x[i] = a[ia]; ia++; } else if (a[ia] < b[ib]) { x[i] = a[ia]; ia++; } else { x[i] = b[ib]; ib++; } i++; } finished = true; } } It turns out that function that does not use multithreading actually runs faster. Why? Does the operating system and the java virtual machine not "communicate" effectively enough to place the different threads on different cores? Or am I missing something obvious?

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  • PHP foreach loop through multidimensional array

    - by Muiter
    I have an multidimensional array, how can I use it? I want to use each seperate array in an for loop. I have this code <?php foreach ($calculatie_id[$i] as $value) { echo $value; } ? print_r($calculatie_id); gives Array ( [0] = Array ( [0] = 4 [1] = 6 ) [1] = Array ( [0] = 1 [1] = 5 ) [2] = Array ( [0] = 5 [1] = 6 ) [3] = ) But when using the foreach I only get 46

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  • How to make this game loop deterministic

    - by Lanaru
    I am using the following game loop for my pacman clone: long prevTime = System.currentTimeMillis(); while (running) { long curTime = System.currentTimeMillis(); float frameTime = (curTime - prevTime) / 1000f; prevTime = curTime; while (frameTime > 0.0f) { final float deltaTime = Math.min(frameTime, TIME_STEP); update(deltaTime); frameTime -= deltaTime; } repaint(); } The thing is, I don't always get the same ghost movement every time I run the game (their logic is deterministic), so it must be the game loop. I imagine it's due to the final float deltaTime = Math.min(frameTime, TIME_STEP); line. What's the best way of modifying this to perform the exact same way every time I run it? Also, any further improvements I can make?

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  • PHP: Loop or no loop?

    - by Joseph Robidoux
    In this situation, is it better to use a loop or not? echo "0"; echo "1"; echo "2"; echo "3"; echo "4"; echo "5"; echo "6"; echo "7"; echo "8"; echo "9"; echo "10"; echo "11"; echo "12"; echo "13"; or $number = 0; while ($number != 13) { echo $number; $number = $number + 1; }

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  • Async.Parallel or Array.Parallel.Map ?

    - by gurteen2
    Hello- I'm trying to implement a pattern I read from Don Syme's blog (http://blogs.msdn.com/dsyme/archive/2010/01/09/async-and-parallel-design-patterns-in-f-parallelizing-cpu-and-i-o-computations.aspx) which suggests that there are opportunities for massive performance improvements from leveraging asynchronous I/O. I am currently trying to take a piece of code that "works" one way, using Array.Parallel.Map, and see if I can somehow achieve the same result using Async.Parallel, but I really don't understand Async.Parallel, and cannot get anything to work. I have a piece of code (simplified below to illustrate the point) that successfully retrieves an array of data for one cusip. (A price series, for example) let getStockData cusip = let D = DataProvider() let arr = D.GetPriceSeries(cusip) return arr let data = Array.Parallel.map (fun x -> getStockData x) stockCusips So this approach contructs an array of arrays, by making a connection over the internet to my data vendor for each stock (which could be as many as 3000) and returns me an array of arrays (1 per stock, with a price series for each one). I admittedly don't understand what goes on underneath Array.Parallel.map, but am wondering if this is a scenario where there are resources wasted under the hood, and it actually could be faster using asynchronous I/O? So to test this out, I have attempted to make this function using asyncs, and I think that the function below follows the pattern in Don Syme's article using the URLs, but it won't compile with "let!". let getStockDataAsync cusip = async { let D = DataProvider() let! arr = D.GetData(cusip) return arr } The error I get is: This expression was expected to have type Async<'a but here has type obj It compiles fine with "let" instead of "let!", but I had thought the whole point was that you need the exclamation point in order for the command to run without blocking a thread. So the first question really is, what's wrong with my syntax above, in getStockDataAsync, and then at a higher level, can anyone offer some additional insight about asychronous I/O and whether the scenario I have presented would benefit from it, making it potentially much, much faster than Array.Parallel.map? Thanks so much.

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  • Addind the sum of numbers using a loop statement

    - by Deonna
    I need serious help diving the positive numbers and the negative numbers. I am to accumulate the total of the negative values and separately accumulate the total of the positive values. After the loop, you are then to display the sum of the negative values and the sum of the positive values. The data is suppose to look like this: -2.3 -1.9 -1.5 -1.1 -0.7 -0.3 0.1 0.5 0.9 1.3 1.7 2.1 2.5 2.9 Sum of negative values: -7.8 Sum of positive values: 12 So far I have this: int main () { int num, num2, num3, num4, num5, sum, count, sum1; int tempVariable = 0; int numCount = 100; int newlineCount = 0, newlineCount1 = 0; float numCount1 = -2.3; while (numCount <= 150) { cout << numCount << " "; numCount += 2; newlineCount ++; if(newlineCount == 6) { cout<< " " << endl; newlineCount = 0; } } **cout << "" << endl; while (numCount1 <=2.9 ) { cout << numCount1 << " "; numCount1 += 0.4; newlineCount1 ++; } while ( newlineCount1 <= 0 && newlineCount >= -2.3 ); cout << "The sum is " << newlineCount1 << endl;** return 0; }

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  • Parallel Desktops: installing Parallel Tools on Ubuntu

    - by Patrick
    hi, I get the following error when I try to install Parallel Tools on my Ubuntu in Parallel Desktop. I follow the istructions, running sh install from terminal: I follow the UI istructions and then the installation stops with this error message: E: Couldn't find package dkms Fri May 7 14:34:20 PDT 2010 Start installation or upgrade of Guest Tools Installed Guest Tools were not found Perform installation into the /usr/lib/parallels-tools directory cat: /usr/lib/parallels-tools/kmods/../version: No such file or directory Start installation of prl_eth kernel module make: Entering directory `/usr/lib/parallels-tools/kmods' cd prl_eth/pvmnet && make make[1]: Entering directory `/usr/lib/parallels-tools/kmods/prl_eth/pvmnet' make -C /lib/modules/2.6.32-21-generic/build M=/usr/lib/parallels-tools/kmods/prl_eth/pvmnet make[2]: Entering directory `/usr/src/linux-headers-2.6.32-21-generic' LD /usr/lib/parallels-tools/kmods/prl_eth/pvmnet/built-in.o CC [M] /usr/lib/parallels-tools/kmods/prl_eth/pvmnet/pvmnet.o LD [M] /usr/lib/parallels-tools/kmods/prl_eth/pvmnet/prl_eth.o Building modules, stage 2. MODPOST 1 modules WARNING: modpost: missing MODULE_LICENSE() in /usr/lib/parallels-tools/kmods/prl_eth/pvmnet/prl_eth.o thanks

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  • Recommended main loop style

    - by Frootmig-H
    I've just begun attempting an FPS with JMonkeyEngine, but I'm currently stuck as to the best way to implement the main loop - especially with regards to non-instantaneous user actions. By that, I mean things like reloading a weapon. The user starts the action, and it continues for a while with an animation and some sound, and when it completes, game state updates. (I should mention that it's not technically a loop, it's an update method, called as often as possible. Is that different? Me no understand terminology). So, far I've considered : Animation driven Player presses reload Start reload animation If user stars another action, abort animation, start new action. When the animation_complete event is received (JMonkeyEngine provides this), update ammo counters. Event driven Player presses reload Start reload animation Queue up a out-of-thread method to be called at time t + (duration of reload animation) If user starts another action, cancel both animation and queued method. When queued method executes, update ammo. This avoids relying on the animation event (JMonkeyEngine has a particular quirk), but brings in the possibility of thread problems. 'Blocking' (not sure of the correct term) Player presses reload Start reloading animation reloading = true reloadedStartTime = now while (reloading && ((now - reloadingStartTime) < reloadingDuration)) { If user starts another action, break and cancel reloading. } Update ammo counters reloading = false My main concern is that actions can interrupt each other. Reloading can be interrupted by firing, or by dropping or changing weapon, crouching can be interrupted by running, etc. What's the recommended way to handle this? What are the advantages and disadvantages of each method? I'm leaning towards event-driven, even though it requires more care; failing that, blocking.

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  • Inauguration Of My Laptop

    - by Pawan_Mishra
    Today I received my new laptop which is an Intel Core i5-2450M @ 2.50GHz 4 GB RAM machine . The other laptop(office provided) which I have used for past two years for programming is an Intel Core2 Duo T6570 @ 2.10GHz machine. Reason why I am talking about the laptops that I own is because of my interest in writing multi-threaded/parallel code using the new TPL API provided in the .Net 4.0 framework. I have spent significant amount of time in past one year writing code using the Parallel API of .Net...(read more)

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  • HTML5/JS - Choppy Game Loop

    - by Rikonator
    I have been experimenting with HTML5/JS, trying to create a simple game when I hit a wall. My choice of game loop is too choppy to be actually of any use in a game. I'm trying for a fixed time step loop, rendering only when required. I simply use a requestAnimationFrame to run Game.update which finds the elapsed time since the last update, and calls State.update to update and render the current state. State.prototype.update = function(ms) { this.ticks += ms; var updates = 0; while(this.ticks >= State.DELTA_TIME && updates < State.MAX_UPDATES) { this.updateState(); this.updateFrameTicks += State.DELTA_TIME; this.updateFrames++; if(this.updateFrameTicks >= 1000) { this.ups = this.updateFrames; this.updateFrames = 0; this.updateFrameTicks -= 1000; } this.ticks -= State.DELTA_TIME; updates++; } if(updates > 0) { this.renderFrameTicks += updates*State.DELTA_TIME; this.renderFrames++; if(this.renderFrameTicks >= 1000) { this.rps = this.renderFrames; this.renderFrames = 0; this.renderFrameTicks -= 1000; } this.renderState(updates*State.DELTA_TIME); } }; But this strategy does not work very well. This is the result: http://jsbin.com/ukosuc/1 (Edit). As it is apparent, the 'game' has fits of lag, and when you tab out for a long period and come back, the 'game' behaves unexpectedly - updates faster than intended. This is either a problem due to something about game loops that I don't quite understand yet, or a problem due to implementation which I can't pinpoint. I haven't been able to solve this problem despite attempting several variations using setTimeout and requestAnimationFrame. (One such example is http://jsbin.com/eyarod/1/edit). Some help and insight would really be appreciated!

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  • Mixing Objective-C and C++: Game Loop Parts

    - by Peteyslatts
    I'm trying to write all of my game in C++ except for drawing and game loop timing. Those parts are going to be in Objective-C for iOS. Right now, I have ViewController handling the update cycle, but I want to create a GameModel class that ViewController could update. I want GameModel to be in C++. I know how to integrate these two classes. My problem is how to have these two parts interact with the drawing and image loading. GameModel will keep track of a list of children of type GameObject. These GameObjects update every frame, and then need to pass position and visibility data to whatever class or method will handle drawing. I feel like I'm answering my own question now (talking it out helps) but would it be a good idea to put all of the visible game objects into an array at the end of the update method, return it, and use that to update graphics inside ViewController?

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  • javascript game loop and game update design

    - by zuo
    There is a main game loop in my program, which calls game update every frame. However, to make better animation and better control, there is a need to implement a function like updateEveryNFrames(n, func). I am considering implementing a counter for each update. The counter will be added by one each frame. The update function will be invoked according to the counter % n. For example, in a sequence of sprites animation, I can use the above function to control the speed of the animation. Can some give some advice or other solutions?

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  • Why is this PHP loop rendering every row twice?

    - by Christopher
    I'm working on a real frankensite here not of my own design. There's a rudimentary CMS and one of the pages shows customer records from a MySQL DB. For some reason, it has no probs picking up the data from the DB - there's no duplicate records - but it renders each row twice. The page PHP is viewable at http://christopher.pastebin.com/DQkjjG3s (attempted to include in this post but it was horribly mangled, think it's important to have it all in context). I'm not the world's best PHP expert but I think I can see an error in a for loop when there is one... But everything looks ok to me. You'll notice that the customer name is clickable; clicking takes you to another page where you can view their full info as held in the DB - and for both rows, the customer ID is identical, and manually checking the DB shows there's no duplicate entries. The code is definitely rendering each row twice, but for what reason I have no idea. All pointers / advice appreciated.

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  • Passing elapsed time to the update function from the game loop

    - by Sri Harsha Chilakapati
    I want to pass the time elapsed to the update() method as this would make easy to implement the animations and time related concepts. Here's my game-loop. public void gameLoop(){ boolean running = true; long gameTime = getCurrentTime(); long elapsedTime = 0; long lastUpdateTime = 0; int loops; while (running){ loops = 0; while(getCurrentTime()>gameTime && loops<Global.MAX_FRAMESKIP){ elapsedTime = getCurrentTime() - lastUpdateTime; lastUpdateTime = getCurrentTime(); update(elapsedTime); gameTime += SKIP_STEPS; loops++; } displayGame(); } } getCurrentTime() method public long getCurrentTime(){ return (System.nanoTime()/1000000); } update() method long time = 0; public void update(long elapsedTime){ time += elapsedTime; if (time>=1000){ System.out.println("A second elapsed"); time -= 1000; } } But this is printing the message for 3 seconds. Thanks.

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  • Most useful parallel programming algorithm?

    - by Zubair
    I recenty asked a question about parallel programming algorithms which was closed quite fast due to my bad ability to communicate my intent: http://stackoverflow.com/questions/2407631/what-is-the-most-useful-parallel-programming-algorithm-closed I had also recently asked another question, specifically: http://stackoverflow.com/questions/2407493/is-mapreduce-such-a-generalisation-of-another-programming-principle/2407570#2407570 The other question was specifically about map reduce and to see if mapreduce was a more specific version of some other concept in parallel programming. This question (about a useful parallel programming algorithm) is more about the whole series of algorithms for parallel programming. You will have to excuse me though as I am quite new to parallel programming, so maybe MapReduce or something that is a more general form of mapreduce is the "only" parallel programming construct which is available, in which case I apologise for my ignorance

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  • Python Access Parallel Port

    - by PPTim
    Hi, I've been trying to access the parallel port with pyParallel, which is in the same sourceforge as PySerial: http://sourceforge.net/projects/pyserial/files/ I'm getting a WidowsError: exception: priviledged instruciton. Has anyone used this module before? import parallel p = parallel.Parallel() Traceback (most recent call last): File "<interactive input>", line 1, in <module> File "C:\Python26\lib\site-packages\parallel\parallelwin32.py", line 74, in __init__ self.ctrlReg = _pyparallel.inp(self.ctrlRegAdr) WindowsError: exception: priviledged instruction

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  • Parallel Computing in .Net 4.0

    - by kaleidoscope
    Technorati Tags: Ram,Parallel Computing in .Net 4.0 Parallel computing is the simultaneous use of multiple compute resources to solve a computational problem: To be run using multiple CPUs A problem is broken into discrete parts that can be solved concurrently Each part is further broken down to a series of instructions Instructions from each part execute simultaneously on different CPUs Parallel Extensions in .NET 4.0 provides a set of libraries and tools to achieve the above mentioned objectives. This supports two paradigms of parallel computing Data Parallelism – This refers to dividing the data across multiple processors for parallel execution.e.g we are processing an array of 1000 elements we can distribute the data between two processors say 500 each. This is supported by the Parallel LINQ (PLINQ) in .NET 4.0 Task Parallelism – This breaks down the program into multiple tasks which can be parallelized and are executed on different processors. This is supported by Task Parallel Library (TPL) in .NET 4.0 A high level view is shown below:

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