Search Results

Search found 11135 results on 446 pages for 'thread safe'.

Page 398/446 | < Previous Page | 394 395 396 397 398 399 400 401 402 403 404 405  | Next Page >

  • iPhone: Low memory crash...

    - by MacTouch
    Once again I'm hunting memory leaks and other crazy mistakes in my code. :) I have a cache with frequently used files (images, data records etc. with a TTL of about one week and a size limited cache (100MB)). There are sometimes more then 15000 files in a directory. On application exit the cache writes an control file with the current cache size along with other useful information. If the applications crashes for some reason (sh.. happens sometimes) I have in such case to calculate the size of all files on application start to make sure I know the cache size. My app crashes at this point because of low memory and I have no clue why. Memory leak detector does not show any leaks at all. I do not see any too. What's wrong with the code below? Is there any other fast way to calculate the total size of all files within a directory on iPhone? Maybe without to enumerate the whole contents of the directory? The code is executed on the main thread. NSUInteger result = 0; NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSDirectoryEnumerator *dirEnum = [[[NSFileManager defaultManager] enumeratorAtPath:path] retain]; int i = 0; while ([dirEnum nextObject]) { NSDictionary *attributes = [dirEnum fileAttributes]; NSNumber* fileSize = [attributes objectForKey:NSFileSize]; result += [fileSize unsignedIntValue]; if (++i % 500 == 0) { // I tried lower values too [pool drain]; } } [dirEnum release]; dirEnum = nil; [pool release]; pool = nil; Thanks, MacTouch

    Read the article

  • JRuby app throws exception in Spring

    - by mat3001
    I am trying to run a JRuby app in Spring. I use Eclipse to run it. But it doesn't compile. Does anybody know what's going on here? Exception in thread "Launcher:/oflaDemo" [INFO] [Launcher:/oflaDemo] org.springframework.beans.factory.support.DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@4a009ab0: defining beans [placeholderConfig,web.context,web.scope,web.handler,demoService.service]; parent: org.springframework.beans.factory.support.DefaultListableBeanFactory@f5d8d75 [INFO] [Launcher:/installer] org.red5.server.service.Installer - Installer service created org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'web.scope' defined in ServletContext resource [/WEB-INF/red5-web.xml]: Initialization of bean failed; nested exception is org.springframework.beans.TypeMismatchException: Failed to convert property value of type [org.springframework.scripting.jruby.JRubyScriptFactory] to required type [org.red5.server.api.IScopeHandler] for property 'handler'; nested exception is java.lang.IllegalArgumentException: Cannot convert value of type [org.springframework.scripting.jruby.JRubyScriptFactory] to required type [org.red5.server.api.IScopeHandler] for property 'handler': no matching editors or conversion strategy found at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:480) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409) at java.security.AccessController.doPrivileged(Native Method) I don't have a lot of experience with Spring, so I would really appreciate hits. If you're familiar with red5 - yes it's the oflademo app supplied by red5.

    Read the article

  • Is there a better way to write named-pipes in F#?

    - by Niran
    Hi I am new to F#. I am trying to communicate with java from F# using named pipe. The code below works but I am not sure if there is a better way to do this (I know the infinite loop is a bad idea but this is just a proof of concept) if anyone have any idea to improve this code please post your comments. Thanks in advance Niran open System.IO open System.IO.Pipes exception OuterError of string let continueLooping = true while continueLooping do let pipeServer = new NamedPipeServerStream("testpipe", PipeDirection.InOut, 4) printfn "[F#] NamedPipeServerStream thread created." //wait for connection printfn "[F#] Wait for a client to connect" pipeServer.WaitForConnection() printfn "[F#] Client connected." try // Stream for the request. let sr = new StreamReader(pipeServer) // Stream for the response. let sw = new StreamWriter(pipeServer) sw.AutoFlush <- true; // Read request from the stream. let echo = sr.ReadLine(); printfn "[F#] Request message: %s" echo // Write response to the stream. sw.WriteLine("[F#]: " + echo) pipeServer.Disconnect() with | OuterError(str) -> printfn "[F#]ERROR: %s" str printfn "[F#] Client Closing." pipeServer.Close()

    Read the article

  • BackgroundWorker

    - by vdh_ant
    Hi guys I'm working on some code that calls a service. This service call could fail and if it does I want the system to try again until it works or too much time has passed. I am wondering where I am going wrong as the following code doesn't seem to be working correctly... It randomly only does one to four loops... protected virtual void ProcessAsync(object data, int count) { var worker = new BackgroundWorker(); worker.DoWork += (sender, e) => { throw new InvalidOperationException("oh shiznit!"); }; worker.RunWorkerCompleted += (sender, e) => { //If an error occurs we need to tell the data about it if (e.Error != null) { count++; System.Threading.Thread.Sleep(count * 5000); if (count <= 10) { if (count % 5 == 0) this.Logger.Fatal("LOAD ERROR - The system can't load any data", e.Error); else this.Logger.Error("LOAD ERROR - The system can't load any data", e.Error); this.ProcessAsync(data, count); } } }; worker.RunWorkerAsync(); } Cheers Anthony

    Read the article

  • How to run an async task afor every x mins in android?

    - by Shan
    how to run the async task at specific time? (I want to run it every 2 mins) I tried using post delayed but it's not working? tvData.postDelayed(new Runnable(){ @Override public void run() { readWebpage(); }}, 100); In the above code readwebpage is function which calls the async task for me.. Right now below is the method which I am using public void onCreate(Bundle savedInstanceState) { readwebapage(); } public void readWebpage() { DownloadWebPageTask task = new DownloadWebPageTask(); task.execute("http://www.google.com"); } private class DownloadWebPageTask extends AsyncTask<String, Void, String> { @Override protected String doInBackground(String... urls) { String response1 = ""; response1=read(); //read is my another function which does the real work response1=read(); super.onPostExecute(response1); return response1; } protected void onPostExecute(String result) { try { Thread.sleep(100); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } TextView tvData = (TextView) findViewById(R.id.TextView01); tvData.setText(result); DownloadWebPageTask task = new DownloadWebPageTask(); task.execute(new String[] { "http://www.google.com" }); } } This is what I my code is and it works perfectly fine but the big problem I drains my battery?

    Read the article

  • Error Reading Image

    - by javawarrior
    When I tried to open a simple smile.png image using package com.java3d.java3d.graphics; import java.awt.Color; import java.awt.image.BufferedImage; import java.io.File; import javax.imageio.ImageIO; public class Texture { public static Render floor = loadBitMap("smile.png"); public Texture(){} public static Render loadBitMap(String fileName) { try { BufferedImage image = ImageIO.read(Thread.currentThread().getContextClassLoader().getResource(fileName)); System.out.print(image==null); int width = image.getWidth(); System.out.println(width); int height = image.getHeight(); System.out.println(height); System.out.println(image.getRGB(4, 4)); Render result = new Render(width, height); image.getRGB(0, 0, width, height, result.pixels, 0, width); return result; } catch (Exception e) { System.out.println("CRASH!"); throw new RuntimeException(e); } } } it returns every pixel as -1; what could be causing this problem? Here is the image:

    Read the article

  • When should EntityManagerFactory instance be created/opened ?

    - by masato-san
    Ok, I read bunch of articles/examples how to write Entity Manager Factory in singleton. One of them easiest for me to understand a bit: http://javanotepad.blogspot.com/2007/05/jpa-entitymanagerfactory-in-web.html I learned that EntityManagerFactory (EMF) should only be created once preferably in application scope. And also make sure to close the EMF once it's used (?) So I wrote EMF helper class for business methods to use: public class EmProvider { private static final String DB_PU = "KogaAlphaPU"; public static final boolean DEBUG = true; private static final EmProvider singleton = new EmProvider(); private EntityManagerFactory emf; private EmProvider() {} public static EmProvider getInstance() { return singleton; } public EntityManagerFactory getEntityManagerFactory() { if(emf == null) { emf = Persistence.createEntityManagerFactory(DB_PU); } if(DEBUG) { System.out.println("factory created on: " + new Date()); } return emf; } public void closeEmf() { if(emf.isOpen() || emf != null) { emf.close(); } emf = null; if(DEBUG) { System.out.println("EMF closed at: " + new Date()); } } }//end class And my method using EmProvider: public String foo() { EntityManager em = null; List<Object[]> out = null; try { em = EmProvider.getInstance().getEntityManagerFactory().createEntityManager(); Query query = em.createNativeQuery(JPQL_JOIN); //just some random query out = query.getResultList(); } catch(Exception e) { //handle error.... } finally { if(em != null) { em.close(); //make sure to close EntityManager } } I made sure to close EntityManager (em) within method level as suggested. But when should EntityManagerFactory be closed then? And why EMF has to be singleton so bad??? I read about concurrency issues but as I am not experienced multi-thread-grammer, I can't really be clear on this idea.

    Read the article

  • Exception when click DataGridview tab c#, .Net 4.0

    - by Nguyen Nam
    My winform app have two tab and multi thread, one is main tab and other is log tab. I only use log tab to show logs in a datagridview control. Exception is random occurred when click to log tab (Not click to row or colunm), i have try but can not find anyway to fix it. This is the error log: Message : Object reference not set to an instance of an object. Source : System.Windows.Forms TargetSite : System.Windows.Forms.DataGridViewElementStates GetRowState(Int32) StackTrace : at System.Windows.Forms.DataGridViewRowCollection.GetRowState(Int32 rowIndex) at System.Windows.Forms.DataGridView.ComputeHeightOfFittingTrailingScrollingRows(Int32 totalVisibleFrozenHeight) at System.Windows.Forms.DataGridView.GetOutOfBoundCorrectedHitTestInfo(HitTestInfo& hti, Int32& mouseX, Int32& mouseY, Int32& xOffset, Int32& yOffset) at System.Windows.Forms.DataGridView.OnMouseMove(MouseEventArgs e) at System.Windows.Forms.Control.WmMouseMove(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.DataGridView.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) Message : Object reference not set to an instance of an object. Source : System.Windows.Forms TargetSite : Void ClearInternal(Boolean) StackTrace : at System.Windows.Forms.DataGridViewRowCollection.ClearInternal(Boolean recreateNewRow) at System.Windows.Forms.DataGridView.OnClearingColumns() at System.Windows.Forms.DataGridViewColumnCollection.Clear() at System.Windows.Forms.DataGridView.Dispose(Boolean disposing) at System.ComponentModel.Component.Dispose() at System.Windows.Forms.Control.Dispose(Boolean disposing) at System.ComponentModel.Component.Dispose() at System.Windows.Forms.Control.Dispose(Boolean disposing) at System.Windows.Forms.TabControl.Dispose(Boolean disposing) at System.ComponentModel.Component.Dispose() at System.Windows.Forms.Control.Dispose(Boolean disposing) at System.Windows.Forms.Form.Dispose(Boolean disposing) Update status code: private void updateMessage(int index, string message) { try { this.dgForums.Rows[index].Cells["ColStatus"].Value = message; System.Windows.Forms.Application.DoEvents(); } catch { } }

    Read the article

  • How can i mock or test my deferred execution functionality?

    - by cottsak
    I have what could be seen as a bizarre hybrid of IQueryable<T> and IList<T> collections of domain objects passed up my application stack. I'm trying to maintain as much of the 'late querying' or 'lazy loading' as possible. I do this in two ways: By using a LinqToSql data layer and passing IQueryable<T>s through by repositories and to my app layer. Then after my app layer passing IList<T>s but where certain elements in the object/aggregate graph are 'chained' with delegates so as to defer their loading. Sometimes even the delegate contents rely on IQueryable<T> sources and the DataContext are injected. This works for me so far. What is blindingly difficult is proving that this design actually works. Ie. If i defeat the 'lazy' part somewhere and my execution happens early then the whole thing is a waste of time. I'd like to be able to TDD this somehow. I don't know a lot about delegates or thread safety as it applies to delegates acting on the same source. I'd like to be able to mock the DataContext and somehow trace both methods of deferring (IQueryable<T>'s SQL and the delegates) the loading so that i can have tests that prove that both functions are working at different levels/layers of the app/stack. As it's crucial that the deferring works for the design to be of any value, i'd like to see tests fail when i break the design at a given level (separate from the live implementation). Is this possible?

    Read the article

  • Stop NSXMLParser Instance from Causing _NSAutoreleaseNoPool

    - by PF1
    Hi Everyone: In my iPhone application, I have an instance of NSXMLParser that is set to a custom delegate to read the XML. This is then moved into its own thread so it can update the data in the background. However, ever since I have done this, it has been giving me a lot of _NSAutoreleaseNoPool warnings in the console. I have tried to add a NSAutoreleasePool to each of my delegate classes, however, this hasn't seemed to solve the problem. I have included my method of creating the NSXMLParser in case that is at fault. NSURL *url = [[NSURL alloc] initWithString:@"http://www.mywebsite.com/xmlsource.xml"]; NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:url]; CustomXMLParser *parser = [[CustomXMLParser alloc] init]; parser.managedObjectContext = self.managedObjectContext; parser = [parser initXMLParser]; [xmlParser setDelegate:parser]; [NSThread detachNewThreadSelector:@selector(parse) toTarget:xmlParser withObject:nil]; If anyone has any ideas to get rid of this problem, I would really appreciate it. Thanks.

    Read the article

  • Google AppEngine + Local JUnit Tests + Jersey framework + Embedded Jetty

    - by xamde
    I use Google Appengine for Java (GAE/J). On top, I use the Jersey REST-framework. Now i want to run local JUnit tests. The test sets up the local GAE development environment ( http://code.google.com/appengine/docs/java/tools/localunittesting.html ), launches an embedded Jetty server, and then fires requests to the server via HTTP and checks responses. Unfortunately, the Jersey/Jetty combo spawns new threads. GAE expects only one thread to run. In the end, I end up having either no datstore inside the Jersey-resources or multiple, having different datastore. As a workaround I initialise the GAE local env only once, put it in a static variable and inside the GAE resource I add many checks (This threads has no dev env? Re-use the static one). And these checks should of course only run inside JUnit tests.. (which I asked before: "How can I find out if code is running inside a JUnit test or not?" - I'm not allowed to post the link directly here :-|)

    Read the article

  • iPhone --- 3DES Encryption returns "wrong" results?

    - by Jan Gressmann
    Hello fellow developers, I have some serious trouble with a CommonCrypto function. There are two existing applications for BlackBerry and Windows Mobile, both use Triple-DES encryption with ECB mode for data exchange. On either the encrypted results are the same. Now I want to implent the 3DES encryption into our iPhone application, so I went straight for CommonCrypto: http://www.opensource.apple.com/source/CommonCrypto/CommonCrypto-32207/CommonCrypto/CommonCryptor.h I get some results if I use CBC mode, but they do not correspond with the results of Java or C#. Anyway, I want to use ECB mode, but I don't get this working at all - there is a parameter error showing up... This is my call for the ECB mode... I stripped it a little bit: const void *vplainText; plainTextBufferSize = [@"Hello World!" length]; bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1); plainText = (const void *) [@"Hello World!" UTF8String]; NSString *key = @"abcdeabcdeabcdeabcdeabcd"; ccStatus = CCCrypt(kCCEncrypt, kCCAlgorithm3DES, kCCOptionECBMode, key, kCCKeySize3DES, nil, // iv, not used with ECB plainText, plainTextBufferSize, (void *)bufferPtr, // output bufferPtrSize, &movedBytes); t is more or less the code from here: http://discussions.apple.com/thread.jspa?messageID=9017515 But as already mentioned, I get a parameter error each time... When I use kCCOptionPKCS7Padding instead of kCCOptionECBMode and set the same initialization vector in C# and my iPhone code, the iPhone gives me different results. Is there a mistake by getting my output from the bufferPtr? Currently I get the encrypted stuff this way: NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes]; result = [[NSString alloc] initWithData:myData encoding:NSISOLatin1StringEncoding]; It seems I almost tried every setting twice, different encodings and so on... where is my error?

    Read the article

  • Java Out of memory - Out of heap size

    - by user1907849
    I downloaded the sample program , for file transfer between the client and server. When I try running the program with 1 GB file , I get the Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at Client.main(Client.java:31). Edit: Line no 31: byte [] mybytearray = new byte [FILE_SIZE]; public final static int FILE_SIZE = 1097742336; // receive file long startTime = System.nanoTime(); byte [] mybytearray = new byte [FILE_SIZE]; InputStream is = sock.getInputStream(); fos = new FileOutputStream(FILE_TO_RECEIVED); bos = new BufferedOutputStream(fos); bytesRead = is.read(mybytearray,0,mybytearray.length); current = bytesRead; do { bytesRead = is.read(mybytearray, current, (mybytearray.length-current)); if(bytesRead >= 0) current += bytesRead; } while(bytesRead > -1); bos.write(mybytearray, 0 , current); bos.flush(); Is there any fix for this?

    Read the article

  • GUI blocked while running silent app VC++

    - by deb
    Hi, I have built a GUI interface in C++ (Windows XP, visual c++ 2008). There you can configure some parameters and when I click on the OK button, a silent application is launched (and uses the values setted). When I do this, the GUI frozes and even dissappears if you switch to other windows(it's still there, but you can only see a white space), when the other application's finished the GUI works again. This is the correct behaviour, I don't want the user to be able to edit the fields... but it's a bit ugly when you can't see the GUI. Does anybody know an easy way of being able to switch to other windows and being able to see the the GUI when you switch back? Thanks in advance Edited: Hi, I tried doing this, but the problem is that to run the apps in background I had a function that uses CreateProcess. So both ways the GUI gets frozen: if I create a Thread that creates the process and if I creathe the process directly. Then I wait for the process to finish: if (!CreateProcess( NULL, Args, NULL, NULL, FALSE, CREATE_NEW_CONSOLE, NULL, NULL, &StartupInfo, &ProcessInfo)) { return GetLastError(); } WaitForSingleObject(ProcessInfo.hProcess, INFINITE); if(!GetExitCodeProcess(ProcessInfo.hProcess, &rc)) rc = 0; Any idea?

    Read the article

  • Rebuilding old (2010) django project in 2012

    - by birgit
    I am trying to make an old Django project run again. After seemingly having solved issues with old sorl.thumbnail versions and deprecated expressions I now get this error when running python manage.py runserver I also tried to copy & paste my old files into a new Django project and get the exactly same error. Maybe someone here has a clue where the problem lies? Unhandled exception in thread started by <bound method Command.inner_run of <django.contrib.staticfiles.management.commands.runserver.Command object at 0x2a80510>> Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/django/core/management/commands/runserver.py", line 88, in inner_run self.validate(display_num_errors=True) File "/usr/lib/python2.7/dist-packages/django/core/management/base.py", line 249, in validate num_errors = get_validation_errors(s, app) File "/usr/lib/python2.7/dist-packages/django/core/management/validation.py", line 35, in get_validation_errors for (app_name, error) in get_app_errors().items(): File "/usr/lib/python2.7/dist-packages/django/db/models/loading.py", line 146, in get_app_errors self._populate() File "/usr/lib/python2.7/dist-packages/django/db/models/loading.py", line 61, in _populate self.load_app(app_name, True) File "/usr/lib/python2.7/dist-packages/django/db/models/loading.py", line 78, in load_app models = import_module('.models', app_name) File "/usr/lib/python2.7/dist-packages/django/utils/importlib.py", line 35, in import_module __import__(name) File "/home/me/Documents/wdws/wdws/../wdws/cityofwindows/models.py", line 73, in <module> class Image(models.Model): File "/home/me/Documents/wdws/wdws/../wdws/cityofwindows/models.py", line 83, in Image 'large': {'size': (640, 640)}, File "/usr/lib/python2.7/dist-packages/django/db/models/fields/files.py", line 233, in __init__ super(FileField, self).__init__(verbose_name, name, **kwargs) TypeError: __init__() got an unexpected keyword argument 'extra_thumbnails' I need to re-build the project just for visual documentation locally... so also any hints on how to quickly re-run outdated django-projects are very welcome!! Thanks a lot (using Ubuntu 12.04)

    Read the article

  • Concurrency problem with arrays (Java)

    - by Johannes
    For an algorithm I'm working on I tried to develop a blacklisting mechanism that can blacklist arrays in a specific way: If "1, 2, 3" is blacklisted "1, 2, 3, 4, 5" is also considered blacklisted. I'm quite happy with the solution I've come up with so far. But there seem to be some serious problems when I access a blacklist from multiple threads. The method "contains" (see code below) sometimes returns true, even if an array is not blacklisted. This problem does not occur if I only use one thread, so it most likely is a concurrency problem. I've tried adding some synchronization, but it didn't change anything. I also tried some slightly different implementations using java.util.concurrent classes. Any ideas on how to fix this? public class Blacklist { private static final int ARRAY_GROWTH = 10; private final Node root = new Node(); private static class Node{ private volatile Node[] childNodes = new Node[ARRAY_GROWTH]; private volatile boolean blacklisted = false; public void blacklist(){ this.blacklisted = true; this.childNodes = null; } } public void add(final int[] array){ synchronized (root) { Node currentNode = this.root; for(final int edge : array){ if(currentNode.blacklisted) return; else if(currentNode.childNodes.length <= edge) { currentNode.childNodes = Arrays.copyOf(currentNode.childNodes, edge + ARRAY_GROWTH); } if(currentNode.childNodes[edge] == null) { currentNode.childNodes[edge] = new Node(); } currentNode = currentNode.childNodes[edge]; } currentNode.blacklist(); } } public boolean contains(final int[] array){ synchronized (root) { Node currentNode = this.root; for(final int edge : array){ if(currentNode.blacklisted) return true; else if(currentNode.childNodes.length <= edge || currentNode.childNodes[edge] == null) return false; currentNode = currentNode.childNodes[edge]; } return currentNode.blacklisted; } } }

    Read the article

  • List<T> paging asp.net

    - by user1397978
    Using a three-tier architecture, I have a list of objects List<object> careerList = new List<object>(); ModuleDTO module = new ModuleDTO(); careerList = module.getDegreeCodeByQualification(qualificationCode); which I then add to a gridview like so: gridViewMaster.DataSource = careerList; gridViewMaster.DataBind(); What I'd like to do is then enable paging on the gridview. My gridview so far is: <asp:GridView ID="gridViewMaster" runat="server" AutoGenerateColumns="False" GridLines="None" BorderWidth="1px" CellPadding="2" DataKeyNames="Grouping" ForeColor="Black" onrowdatabound="gridViewMaster_RowDataBound" CssClass="mGrid" PagerStyle-CssClass="pgr" AlternatingRowStyle-CssClass="alt" OnPageIndexChanging="gridView_PageIndexChanging" AllowPaging="True" > Is it possible to do enable paging on a list's without having to change that list to a Datatable or Dataview? If there is a way, this would help a lot. So far my events are as follows: protected void gridView_PageIndexChanging(object sender, GridViewPageEventArgs e) { gridViewMaster.PageIndex = e.NewPageIndex; List<object> careerList = new List<object>(); ModuleDTO module = new ModuleDTO(); careerList = module.getDegreeCodeByQualification(qualificationCode); ModalProgress.Show(); System.Threading.Thread.Sleep(1000); JobPanel.Visible = true; gridViewMaster.DataSource = careerList.Distinct(); gridViewMaster.DataBind(); } Someone PLEASE HELP ME!!! Thank you

    Read the article

  • Java: fastest way to do random reads on huge disk file(s)

    - by cocotwo
    I've got a moderately big set of data, about 800 MB or so, that is basically some big precomputed table that I need to speed some computation by several orders of magnitude (creating that file took several mutlicores computers days to produce using an optimized and multi-threaded algo... I do really need that file). Now that it has been computed once, that 800MB of data is read only. I cannot hold it in memory. As of now it is one big huge 800MB file but splitting in into smaller files ain't a problem if it can help. I need to read about 32 bits of data here and there in that file a lot of time. I don't know before hand where I'll need to read these data: the reads are uniformly distributed. What would be the fastest way in Java to do my random reads in such a file or files? Ideally I should be doing these reads from several unrelated threads (but I could queue the reads in a single thread if needed). Is Java NIO the way to go? I'm not familiar with 'memory mapped file': I think I don't want to map the 800 MB in memory. All I want is the fastest random reads I can get to access these 800MB of disk-based data. btw in case people wonder this is not at all the same as the question I asked not long ago: http://stackoverflow.com/questions/2346722/java-fast-disk-based-hash-set

    Read the article

  • Facebook style messaging system schema design

    - by Jamie
    Hi all, I'm looking to implement a facebook style messaging system (thread messages) into a site of mine. Do you think this schema markup looks okay? Doctrine schema.yml: UserMessage: tableName: user_message actAs: [Timestampable] columns: id: { type: integer(10), primary: true, autoincrement: true } sender_id : { type: integer(10), notnull: true } sender_read: { type: boolean, default: 1 } subject: { type: string(255), notnull: true } message: { type: string(1000), notnull: true } hash: { type: string(32), notnull: true } relations: UserMessageRecipient as Recipient: type: many local: id foreign: message_id UserMessageReply as Reply: type: many local: id foreign: message_id UserMessageReply: tableName: user_message_reply columns: id: { type: integer(10), primary: true, autoincrement: true } user_message_id as message_id: { type: integer(10), notnull: true } message: { type: string(1000), notnull: true } sender_id: { type: integer(10), notnull: true } relations: UserMessage as Message: local: message_id foreign: id type: one UserMessageRecipient: tableName: user_message_recipient actAs: [Timestampable] columns: id: { type: integer(10), primary: true, autoincrement: true } user_message_id as message_id: { type: integer(10), notnull: true } recipient_id: { type: integer(10), notnull: true } recipient_read: { type: boolean, default: 0 } When I a new reply is made,i'll make sure the boolean for "recipient_read" for each recipient is set to false and of course i'll make sure sender_read is set to false too. I'm using a hash for the URL: http://example.com/user/messages/aadeb18f8bdaea49882ec4d2a8a3c062 (As the id will be starting from 1, i don't wish to have http://example.com/user/messages/1. Yeah, I could start incrementing from a bigger number, but i'd prefer to start at 1.) Is this a good way to go about it? Your thoughts and suggestions would be hugely appreciated. Thanks guys!

    Read the article

  • What's so bad about building XML with string concatenation?

    - by wsanville
    In the thread What’s your favorite “programmer ignorance” pet peeve?, the following answer appears, with a large amount of upvotes: Programmers who build XML using string concatenation. My question is, why is building XML via string concatenation (such as a StringBuilder in C#) bad? I've done this several times in the past, as it's sometimes the quickest way for me to get from point A to point B when to comes to the data structures/objects I'm working with. So far, I have come up with a few reasons why this isn't the greatest approach, but is there something I'm overlooking? Why should this be avoided? Probably the biggest reason I can think of is you need to escape your strings manually, and most programmers will forget this. It will work great for them when they test it, but then "randomly" their apps will fail when someone throws an & symbol in their input somewhere. Ok, I'll buy this, but it's really easy to prevent the problem (SecurityElement.Escape to name one). When I do this, I usually omit the XML declaration (i.e. <?xml version="1.0"?>). Is this harmful? Performance penalties? If you stick with proper string concatenation (i.e. StringBuilder), is this anything to be concerned about? Presumably, a class like XmlWriter will also need to do a bit of string manipulation... There are more elegant ways of generating XML, such as using XmlSerializer to automatically serialize/deserialize your classes. Ok sure, I agree. C# has a ton of useful classes for this, but sometimes I don't want to make a class for something really quick, like writing out a log file or something. Is this just me being lazy? If I am doing something "real" this is my preferred approach for dealing w/ XML.

    Read the article

  • @selector and return value

    - by user320926
    The idea it's very easy, i have an http download class, this class must support the http authentication but it's basically a background thread so i would like to avoid to prompt directly to the screen, i would like to use a delegate method to require from outside of the class, like a viewController. But i don't know if is possible or if i have to use a different syntax. This class use this delegate protocol: //Updater.h @protocol Updater <NSObject> -(NSDictionary *)authRequired; @optional -(void)statusUpdate:(NSString *)newStatus; -(void)downloadProgress:(int)percentage; @end @interface Updater : NSThread { ... } This is the call to the delegate method: //Updater.m // This check always fails :( if ([self.delegate respondsToSelector:@selector(authRequired:)]) { auth = [delegate authRequired]; } This is the implementation of the delegate method //rootViewController.m -(NSDictionary *)authRequired; { // TODO: some kind of popup or modal view NSMutableDictionary *ret=[[NSMutableDictionary alloc] init]; [ret setObject:@"utente" forKey:@"user"]; [ret setObject:@"password" forKey:@"pass"]; return ret; }

    Read the article

  • Atomic operations on several transactionless external systems

    - by simendsjo
    Say you have an application connecting 3 different external systems. You need to update something in all 3. In case of a failure, you need to roll back the operations. This is not a hard thing to implement, but say operation 3 fails, and when rolling back, the rollback for operation 1 fails! Now the first external system is in an invalid state... I'm thinking a possible solution is to shut down the application and forcing a manual fix of the external system, but then again... It might already have used this information (and perhaps that's why it failed), or we might not have sufficient access. Or it might not even be a good way to rollback the action! Are there some good ways of handling such cases? EDIT: Some application details.. It's a multi user web application. Most of the work is done with scheduled jobs (through Quartz.Net), so most operations is run in it's own thread. Some user actions should trigger jobs that update several systems though. The external systems are somewhat unstable. I Was thinking of changing the application to use the Command and Unit Of Work pattern

    Read the article

  • Why do you need "extern C" for in C++ callbacks to C functions?

    - by Artyom
    Hello, I find such examples in Boost code. namespace boost { namespace { extern "C" void *thread_proxy(void *f) { .... } } // anonymous void thread::thread_start(...) { ... pthread_create(something,0,&thread_proxy,something_else); ... } } // boost Why do you actually need this extern "C"? It is clear that thread_proxy function is private internal and I do not expect that it would be mangled as "thread_proxy" because I actually do not need it mangled at all. In fact in all my code that I had written and that runs on may platforms I never used extern "C" and this had worked as-as with normal functions. Why extern "C" is added? My problem is that extern "C" function pollute global name-space and they do not actually hidden as author expects. This is not duplicate! I'm not talking about mangling and external linkage. It is obvious in this code that external linkage is unwanted!

    Read the article

  • Queueing method calls - any idea how?

    - by TomTom
    I write a heavily asynchronseous application. I am looking for a way to queue method calls, similar to what BeginInvoke / EndInvoke does.... but on my OWN queue. The reaqson is that I am having my own optimized message queueing system using a threadpool but at the same time making sure every component is single threaded in the requests (i.e. one thread only handles messages for a component). I Have a lot of messages going back and forth. For limited use, I would really love to be able to just queue a message call with parameters, instead of having to define my own parameter, method wrapping / unwrapping just for the sake of doing a lot of admnistrative calls. I also do not always want to bypass the queue, and I definitely do not want the sending service to wait for the other service to respond. Anyone knows of a way to intercept a method call? Some way to utilize TransparentProxy / Virtual Proxy for this? ;) ServicedComponent? I would like this to be as little overhead as possible ;)

    Read the article

  • Controller actions appear to be synchronous though on different requests?

    - by Oded
    I am under the impression that the below code should work asynchronously. However, when I am looking at firebug, I see the requests fired asynchronously, but the results coming back synchronously: Controller: [HandleError] public class HomeController : Controller { public ActionResult Status() { return Content(Session["status"].ToString()); } public ActionResult CreateSite() { Session["status"] += "Starting new site creation"; Thread.Sleep(20000); // Simulate long running task Session["status"] += "<br />New site creation complete"; return Content(string.Empty); } } Javascript/jQuery: $(document).ready(function () { $.ajax({ url: '/home/CreateSite', async: true, success: function () { mynamespace.done = true; } }); setTimeout(mynamespace.getStatus, 2000); }); var mynamespace = { counter: 0, done: false, getStatus: function () { $('#console').append('.'); if (mynamespace.counter == 4) { mynamespace.counter = 0; $.ajax({ url: '/home/Status', success: function (data) { $('#console').html(data); } }); } if (!mynamespace.done) { mynamespace.counter++; setTimeout(mynamespace.getStatus, 500); } } } Addtional information: IIS 7.0 Windows 2008 R2 Server Running in a VMWare virutual machine Can anyone explain this? Shouldn't the Status action be returning practically immediately instead of waiting for CreateSite to finish? Edit: How can I get the long running process to kick off and still get status updates?

    Read the article

< Previous Page | 394 395 396 397 398 399 400 401 402 403 404 405  | Next Page >