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• Should i use HttpResponse.End() for a fast webapp?

  - by acidzombie24

  HttpResponse.End() seems to throw an exception according to msdn. Right now i have the choice of returning a value to say end thread (it only goes 2 functions deep) or i can call end(). I know that throwing exceptions is significantly slower (read the comment for a C#/.NET test) so if i want a fast webapp should i consider not calling it when it is trivially easy to not call it? -edit- I do have a function call in certain functions and in the constructor in classes to ensure the user is logged in. So i call HttpResponse.End() in enough places although hopefully in regular site usage it doesn't occur too often.

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• Fermat factorization method limit

  - by Fakrudeen

  I am trying to implement Fermat's factorization [Algorithm C in Art of computer programming Vol. 2]. Unfortunately in my edition [ISBN 81-7758-335-2], this algorithm is printed incorrectly. what should be the condition on factor-inner loop below? I am running the loop till y <= n [passed in as limit]. (if (< limit y) 0 (factor-inner x (+ y 2) (- r y) limit)) Is there anyway to avoid this condition altogether, as it will double the speed of loop? (define (factor n) (let ( ( square-root (inexact->exact (floor (sqrt n))) ) ) (factor-inner (+ (* 2 square-root) 1) 1 (- (* square-root square-root) n) n) ) ) (define (factor-inner x y r limit) (if (= r 0) (/ (- x y) 2) (begin (display x)(display " ")(display y)(display " ")(display r)(newline) ;(sleep-current-thread 1) (if (< r 0) (factor-inner (+ x 2) y (+ r x) limit) (if (< limit y) 0 (factor-inner x (+ y 2) (- r y) limit)) ) ) ) )

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• converting NSTimer running not on main runloop to GCD

  - by Justin Galzic

  I have a task that runs periodically and it was originally designed to run on a separate run loop than the main runloop using NSThread and NSTimer. What's the best way to adapt this to take advantage of GCD? Current code: -(void)initiateSomeTask { [NSThread detachNewThreadSelector:@selector(startTimerTask) toTarget:self withObject:nil]; } -(void)startTimerTask { // We won't get back the main runloop since we're on a new thread NSRunLoop *myRunLoop = [NSRunLoop currentRunLoop]; NSPort *myPort = [NSMachPort port]; [myRunLoop addPort:myPort forMode:NSDefaultRunLoopMode]; NSTimer *myTimer = [NSTimer timerWithTimeInterval:10 /* seconds */ target:self selector:@selector(doMyTaskMethod) userInfo:nil repeats:YES]; [myRunLoop addTimer:myTimer forMode:NSRunLoopCommonModes]; [myRunLoop run]; } Is there anything I can do besides replace detachNewThreadSelector with dispatch_async?

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• Using static mutex in a class

  - by Dmitry Yudakov

  I have a class that I can have many instances of. Inside it creates and initializes some members from a 3rd party library (that use some global variables) and is not thread-safe. I thought about using static boost::mutex, that would be locked in my class constructor and destructor. Thus creating and destroying instances among my threads would be safe for the 3rd party members. class MyClass { static boost::mutex mx; // 3rd party library members public: MyClass(); ~MyClass(); }; MyClass::MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // create and init 3rd party library stuff } MyClass::~MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // destroy 3rd party library stuff } I cannot link because I receive error: undefined reference to `MyClass::mx` Do I need some special initialization of such static member? Is the whole conception of static mutex wrong?

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• Two BlockingQueue in the same endless loop?

  - by DrDol

  I have a thread, that processes incomming messages (endless loop). For this, I use a BlockingQueue (Java), which works as quite nice. Now, I want to add a second processor in the same Class oder method. The problem now is, that in the endless loop i have this part newIncomming = this.incommingProcessing.take(); This part blocks if the Queue is empty. I'm looking for a solution to process to queues in the same class. The second queue can only processed, it some data is coming in for the first Queue. Is there a way to handle tow blocking queues in the same endless loop?

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• Java threadpool functionality

  - by cpf

  Hi stackoverflow, I need to make a program with a limited amount of threads (currently using newFixedThreadPool) but I have the problem that all threads get created from start, filling up memory at alarming rate. I wish to prevent this. Threads should only be created shortly before they are executed. e.g.: I call the program and instruct it to use 2 threads in the pool. The program should create & launch the first 2 Threads immediately (obviously), create the next 2 to wait for the previous 2, and at that point wait until one or both of the first 2 ended executing. I thought about extending executor or FixedThreadPool or such. However I have no clue on how to start there and doubt it is the best solution. Easiest would have my main Thread sleeping on intervals, which is not really good either... Thanks in advance!

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• PHP fastest method of reading server response

  - by Peter John

  Hi there, im having some real problems with the lag produced by using fgets to grab the server's response to some batch database calls im making. Im sending through a batch of say, 10,000 calls and ive tracked the lag down to fgets causing the hold up in the speed of my application as the response for each call needs to be grabbed. I have found this thread http://bugs.php.net/bug.php?id=32806 which explains the problem quite well, but hes reading a file, not a server response so fread could be a bit tricky as i could get part of the next line, and extra stuff which i dont want. Any help much appreciated!

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• Maximizing the number of threads to fully utilize all available resources without hindering overall

  - by Matt

  Let's say I have to generate a bunch of result files, and I want to make it as fast as possible. Each result file is generated independently of any other result file; in fact, one could say that each result file is agnostic to every other result file. The resources used to generate each result file is also unique to each. How can I dynamically decide the optimal number of threads to run simultaneously in order to minimize the overall run time? Is my only option to write my own thread manager that watches performance counters and adjust accordingly or does there exists some solid classes that already accomplish this?

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• Java/Swing offscreen rendering (Cobra HTMLPanel -> BufferedImage) Problem: Component doesn't finish

  - by Alterscape

  I'm trying to render the contents of a the Java/Swing Cobra HTML renderer to an offscreen BufferedImage, for use elsewhere in my app: slideViewPanel.setDocument(document, rendererContext); BufferedImage test = new BufferedImage(300,300,BufferedImage.TYPE_INT_RGB); Graphics g = test.getGraphics(); slideViewPanel.paint(g); The resulting image in g shows a partially rendered page -- sometimes the contents of the HTMLFrame before the new document was set; sometimes a half-rendered version of the new document. I gather this is because Cobra's setDocument method just schedules the document for re-rendering, but I'm stepping through in the debugger and I don't see a second thread to do re-rendering. Anyone have any insight into what might be happening here?

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• Java string too long?

  - by wrongusername

  I have the following code in Java (which worked just fine in C++ for some reason) which produces an error: int a; System.out.println("String length: " + input.length()); for(a = 0; ((a + 1) * 97) < input.length(); a++) { System.out.print("Substring at " + a + ": "); System.out.println(input.substring(a * 97, 97)); //other code here... } Output: String length: 340 Substring at 0: HelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHe Substring at 1: Exception in thread "AWT-EventQueue-0" java.lang.StringIndexOutOfBoundsException: String index out of range: -97 //long list of "at ..." stuff Substring at 2: Using a string of length 200, however, the following output is produced: String length: 200 Substring at 0: HelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHe Substring at 1: That is it; no exceptions raised, just... nothing. What is happening here?

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• connecting to a webservice from android - AsyncTask or Service?

  - by football

  I'm writing an android app that will connect to a REST/JSON webservice. Users will be retrieving information, uploading comments, downloading and uploading images etc. I know that I shouldn't keep all this network communication in the Activity/UI thread, as it will cause ANRs. What I'm confused about is whether I should use an AsyncTask or a Service with "manual" threading to accomplish this; With a Service, I'd simply have a public method for each method in the webservice's API. I'd then implement threading within each of these methods. If I used an AsyncTask, I would create a helper class that defined AsyncTasks for each method in the webservice's API. Which method is preferred? Interaction with the webservice will only happen while the user is in the Activity. Once they switch to another application, or exit the program, there is no need for communication with the webservice.

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• Starting a new process in a asp.net web service

  - by Deumber

  I have the following code: public void BeginConvert(object data) { ConverterData cObject = (ConverterData)data; string argument = string.Format("-i \"{0}\" -b {1} \"{2}\"", cObject.Source, compression, cObject.Destiny); Process converterProcess = new Process(); converterProcess.StartInfo.FileName = ffPath; converterProcess.StartInfo.Arguments = argument; converterProcess.StartInfo.WindowStyle = ProcessWindowStyle.Hidden; converterProcess.Start(); converterProcess.WaitForExit(); } I use it in a webservice, i start it in a new thread and it return exit code 1 (error, i'm trying to do a video convertion with ffmpeg library), i impersonate ASP.NET to use a local account with permissions to read and write files, when i run it in my machine running or debugging it works but know thta the web service is running in IIS doest'n. Could someone help me?

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• Python - which multi platform GUI framework to use?

  - by Iacopo

  Hi, I've written a Python GUI application and made it run on Linux, Windows and Mac. The framework I'm using is PyGtk. The final result is not really good: the application looks horrible on Mac, and it is not really 'native' neither on Windows. Furthermore on Mac the windows' behavior is sometimes wrong, with modal dialogs appearing below the main windows. I've explored other frameworks and I've found that a porting may be really hard: PyQt it is huge, difficult to install and to distribute under Mac; PyGui is poor: I need tables and tree views at least; wxPython state explicitly that you have to use a custom python build for Mac Tkinter: didn't check it, only have the impression that it is obsolete I know this question may appear similar to http://stackoverflow.com/questions/394039/which-python-gui-framework but in that thread the portability issue is not really taken in account. Windows and Mac are a must, since most of my user have that systems. Can you also suggest some books?

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• 2008 Datacenter Word Automation issue

  - by Brad

  We have an application that uses word automation. It works fine under Windows XP, but does not work on our Windows Server 2008 64-bit virtual machine running on VMware ESX unless it is running as the domain administrator. Under any other account (including a local admin), Word starts, uses a lot of CPU for 40 seconds when opening a document, and then just hangs. Our application does not access anything not on the local machine, and this machine is not being used for anything else (not a domain controller, etc). I know others have posted similar issues, with the solution of creating a Desktop folder somewhere under the windows directory. We did this, and it did not solve the problem (Word did not get as far as it did before we did this though). Please don't turn this into a thread about why I am trying to do this, whether I should do this, or whether I need to. For argument sake, I don't need to do this, but understanding what privilege a local admin does not have that is needed to do this is a legitimate concern.

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• Custom event listener on Android app

  - by Bilthon

  Hi everybody, I need to set up a simple event listener to refresh a listview from once in a while. The problem is I don't know how could I generate an event. I know that for events like key or button pressing I just need to implement the handler. But in this specific case I actually need to generate the event, which will be fired everytime another running thread of my app wakes up and refreshes it's list of news from a rss feed. I've done everything, but got stucked in here. Can I get any suggestion or link with some more info on how to implement this? Thanks Nelson R. Perez

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• In WPF using a ListView is there an elegant way to auto resize items?

  - by Justin

  I recently wrote, my first, WPF application that has a list of items that are polled from a web-serivce. The items are displayed/data-bound in a ListView via a GridView. A background thread periodically polls the web-serivce and updates the list. If, say, I had three items initially bound to the ListView that simply display a description and the three descriptions where something like: - ProjectA - ProjectB - ProjectC Later a new item is added with a description of 'AReallyReallyLongProjectName', I would end up with a list like: - ProjectA - ProjectB - ProjectC - AReallyR The GridViewColumn would not update it's width and would subsequently cut off any new items that extended the original width. I added this bit of code which forces the column to resize, but it just seems a little hacky. (Just seems weird to set a width just to set it back to nothing to force the resize) if(gridView != null) { foreach(var column in gridView.Columns) { if (double.IsNaN(column.Width) column.Width = column.ActualWidth; column.Width = double.NaN; } } Is there a better, more elegant solution, to accomplish this same thing?

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• How to impose maxlength on textArea in HTML , Javascript

  - by Rakesh Juyal

  I would like to have some functionality by which if i write <textarea maxlength="50"></textarea> <textarea maxlength="150"></textarea> <textarea maxlength="250"></textarea> it will automatically impose the maxlength on the textArea. If possible please donot provide the solution in JQuery. Note: This can be done if i do something like this: <textarea onkeypress="return imposeMaxLength(event, this, 110);" rows="4" cols="50"> function imposeMaxLength(Event, Object, MaxLen) { return (Object.value.length <= MaxLen)||(Event.keyCode == 8 ||Event.keyCode==46||(Event.keyCode>=35&&Event.keyCode<=40)) } copied from another thread But the point is I don't want to write onKeyPress and onKeyUp every time i declare a textArea.

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• Server Emulator Design Pattern

  - by adisembiring

  I wanna build server socket emulator, but I want implement some design pattern there. I will described my case study that I have simplified like these: My Server Socket will always listen client socket. While some request message come from the client socket, the server emulator will response the client through the socket. the response is response code. '00' will describe request message processed successfully, and another response code expect '00' will describe there are some error while processing the message request. IN the server there are some UI, this UI contain check response parameter such as. response code timeout interval While the server want to response the client message, the response code taken from input parameter response form UI check the timeout interval, it will create sleep thread and the interval taken from timeout interval input from UI. I have implement the function, but I create it in one class. I feel it so sucks. Can you suggest me what class / interface that I must create to refactor my code.

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• How to solve the performance decay of a VB.NET 1.1 application?

  - by marco.ragogna

  I have single-thread windows form application written with VB.NET and targeting Framework 1.1. The software communicates with external boards through a serial interface, and it mainly consist of a state machine that run some tests, driven in a loop done with a Timer and an Interval of 50ms. The feedback on the user interface is done through some custom events raised during the tests. The problem that is driving me crazy is that the performance slightly decrease over time, and in particular after 1200/1300 test operations. The memory occupied does not increase over time, it is only the CPU that seems interested by this problem. The strange thing is that, targeting framework 2.0 and using the same identical code, I do not have this problem. I know that is difficult without looking at the code, but do you have suggestions how can I approach the problem?

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• dynamically change bitmap in imageView, android

  - by Junfei Wang

  All, I have a problem related to imageView, android. I have array which contains of 10 bitmap objects, called bm. I have a imageView, called im. Now I wanna show the bitmaps in the array in im one by one, so I did the following: new Thread(new Runnable() { public void run() { for(int j=0;j<10;j++){ im.setImageBitmap(bm[j]); } } }).start(); But the result only shows the last bitmap in the array. Can someone tell me what to do with this issue? Millions of thanks!

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• Database file is inexplicably locked during SQLite commit

  - by sweeney

  Hello, I'm performing a large number of INSERTS to a SQLite database. I'm using just one thread. I batch the writes to improve performance and have a bit of security in case of a crash. Basically I cache up a bunch of data in memory and then when I deem appropriate, I loop over all of that data and perform the INSERTS. The code for this is shown below: public void Commit() { using (SQLiteConnection conn = new SQLiteConnection(this.connString)) { conn.Open(); using (SQLiteTransaction trans = conn.BeginTransaction()) { using (SQLiteCommand command = conn.CreateCommand()) { command.CommandText = "INSERT OR IGNORE INTO [MY_TABLE] (col1, col2) VALUES (?,?)"; command.Parameters.Add(this.col1Param); command.Parameters.Add(this.col2Param); foreach (Data o in this.dataTemp) { this.col1Param.Value = o.Col1Prop; this. col2Param.Value = o.Col2Prop; command.ExecuteNonQuery(); } } this.TryHandleCommit(trans); } conn.Close(); } } I now employ the following gimmick to get the thing to eventually work: private void TryHandleCommit(SQLiteTransaction trans) { try { trans.Commit(); } catch (Exception e) { Console.WriteLine("Trying again..."); this.TryHandleCommit(trans); } } I create my DB like so: public DataBase(String path) { //build connection string SQLiteConnectionStringBuilder connString = new SQLiteConnectionStringBuilder(); connString.DataSource = path; connString.Version = 3; connString.DefaultTimeout = 5; connString.JournalMode = SQLiteJournalModeEnum.Persist; connString.UseUTF16Encoding = true; using (connection = new SQLiteConnection(connString.ToString())) { //check for existence of db FileInfo f = new FileInfo(path); if (!f.Exists) //build new blank db { SQLiteConnection.CreateFile(path); connection.Open(); using (SQLiteTransaction trans = connection.BeginTransaction()) { using (SQLiteCommand command = connection.CreateCommand()) { command.CommandText = DataBase.CREATE_MATCHES; command.ExecuteNonQuery(); command.CommandText = DataBase.CREATE_STRING_DATA; command.ExecuteNonQuery(); //TODO add logging } trans.Commit(); } connection.Close(); } } } I then export the connection string and use it to obtain new connections in different parts of the program. At seemingly random intervals, though at far too great a rate to ignore or otherwise workaround this problem, I get unhandled SQLiteException: Database file is locked. This occurs when I attempt to commit the transaction. No errors seem to occur prior to then. This does not always happen. Sometimes the whole thing runs without a hitch. No reads are being performed on these files before the commits finish. I have the very latest SQLite binary. I'm compiling for .NET 2.0. I'm using VS 2008. The db is a local file. All of this activity is encapsulated within one thread / process. Virus protection is off (though I think that was only relevant if you were connecting over a network?). As per Scotsman's post I have implemented the following changes: Journal Mode set to Persist DB files stored in C:\Docs + Settings\ApplicationData via System.Windows.Forms.Application.AppData windows call No inner exception Witnessed on two distinct machines (albeit very similar hardware and software) Have been running Process Monitor - no extraneous processes are attaching themselves to the DB files - the problem is definitely in my code... Does anyone have any idea whats going on here? I know I just dropped a whole mess of code, but I've been trying to figure this out for way too long. My thanks to anyone who makes it to the end of this question! brian UPDATES: Thanks for the suggestions so far! I've implemented many of the suggested changes. I feel that we are getting closer to the answer...however... The code above technically works however it is non-deterministic! It is not guaranteed to do anything aside from spin in neutral forever. In practice it seems to work somewhere between the 1st and 10th iteration. If i batch my commits at a reasonable interval damage will be mitigated but I really do not want to leave things in this state... More suggestions welcome!

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• Can JNI handle any dll files (Windows)?

  - by henry

  I am new to JNI. And have a few questions : Can JNI handle every type dll exists in windows? I wanted to link a library but it gives me error. Is it possible JNI and the dll are not compatible? Excerpt from VB .NET (It works) Private Declare Function ConnectReader Lib "rfidhid.dll" () As Integer Private Declare Function DisconnectReader Lib "rfidhid.dll" () As Integer Private Declare Function SetAntenna Lib "rfidhid.dll" (ByVal mode As Integer) As Integer Full Code From Java public class MainForm { /** * @param args */ public native int ConnectReader(); public static void main(String[] args) { // TODO Auto-generated method stub MainForm mf = new MainForm(); System.out.println(mf.ConnectReader()); } static { System.loadLibrary("rfidhid"); } } Error code shown Exception in thread "main" java.lang.UnsatisfiedLinkError: MainForm.ConnectReader()I at MainForm.ConnectReader(Native Method) at MainForm.main(MainForm.java:13) Can anyone point to me where I might do wrong

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• NoClassDefFoundError points to the wrong class.

  - by Sora

  I'm validating the installation of a program that consists of a few separate modules. They are not co-dependent. I have apple.jar and orange.jar, they are placed in the same folder and were developed in the same project, but run independent of each other. Running apple.jar goes fine, but orange.jar gives me a NoClassDefFoundError pointing to apple.jar. /usr/java/jre1.6.0_14/bin/java -jar validator.jar Exception in thread "main" java.lang.NoClassDefFoundError: orange/client/Apple Caused by: java.lang.ClassNotFoundException: orange.client.Apple at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) Could not find the main class: validator/client/StormDataXMLGenerator. Program will exit. The manifest file lists Orange as the correct main class. Main-Class: orange/client/Orange Anybody know why it's giving me the NoClassDefFoundError? Thanks in advance!

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• JavaScript on Android randomly stops working

  - by AndersWid

  Hi! I have an application that uses a WebView and a html-page with javascript functions. Randomly the JavaScript functions doesn't seem to be called. It works up to a random point (I have looked at this bug all day) can only be produced on hardware (HTC Legend) not on emulator. Basicly I'm using callback to javaScript whenever the user presses a button, these callbacks tell the html to redraw using javaScript functions. mHandler.post(new Runnable() { public void run() { mWebView.loadUrl("javascript:getDataLine()"); } }); The first line in this javaScript code is an alert that says that it has started, so that I can see that it's working. Settings alerts or console.log's everywhere won't help as it seems the problem is in the webview or in Android itself. I need a way to see what's going on in the background. Maybe see if a previous call failed and stalled the thread or something.

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• Have the default security settings changed in Windows 7 that would affect IPrincipal.IsInRole?

  - by adrianbanks

  We use NTLM auth in our application to determine whether a user can perform certain operations. We use the IPrincipal of their current Windows login (in WinForms applications), calling IsInRole to check for specific group memberships. To check that a user is a local administrator on the machine, we use: AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal); ... bool allowed = Thread.CurrentPrincipal.IsInRole(@"Builtin\Administrators") This works if the current user is the Administrator user, or is another user that is a member of the Builtin\Administrators group. In our testing on Windows 7, we have found that this no longer works as expected. The Administrator user still works fine, but any other user that is a member of the Builtin\Administrators group returns false for the IsInRole call. What could be causing this difference? I have a gut feeling that a default setting has changed somewhere (possible in gpedit), but cannot find anything that looks like the culprit.

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