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  • java statistics collection for performance evaluation

    - by user384706
    What is the most efficient way to collect and report performance statistic analysis from an application? If I have an application that uses a series of network apis, and I want to report statistics at runtime, e.g. Method doA() was called 3 times and consumed on avg 500ms Method doB() was called 5 times and consumed on avg 1200ms etc Then, I thought of using a well defined data structure (of collection) that each thread updates per remote call, and this can be used for the report. But I think that it will make the performance worse, for the time spend for statistics collection. Am I correct? How would I procceed if I used a background thread for this, and the other threads that did the remote calls were unaware of this collection gathering? Thanks

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  • asynchronous calls in asp.net

    - by lockedscope
    in this sample, two threads created; a worker thread created by BeginInvoke and an I/O completion thread created by SendAsync method. but another author in his UnsafeQueueNativeOverlapped example, don't recommend this. i want to use SendAsync or ...Async in an asp.net page and i want to use PageAsyncTask. however, its BeginEventHandler requires AsyncResult to be returned which SendAsync does not return. afaik, event based async pattern is the most recommended way so how could we call SendAsync or any ...Async methods without creating two threads and hurting the performance?

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  • Disable the Go button in the Keyboard for a UITextfield in iphone app.

    - by coder net
    Hi, My app has a screen where keyboard is always visible. The main element of the screen is a UITextfield. For easy data entering, keyboard is always made visible. When the user finishes entering data and hits Go, the app performs a 4,5 seconds action which is done in the background thread in order to show UIActivityIndicatorView. My problem is that the Go button on the keyboard still shows as enabled since the logic is performed in the background. The user could potentially hit the Go again causing it to run again. I am not able to set editable/userinteraction properties to No because then the keyboard disappears. Is there anyway just to disable the Go button or freeze the keyboard until the background thread returns?

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  • What are some good ways to do intermachine locking?

    - by mike
    Our server cluster consists of 20 machines, each with 10 pids of 5 threads. We'd like some way to prevent any two threads, in any pid, on any machine, from modifying the same object at the same time. Our code's written in Python and runs on Linux, if that helps narrow things down. Also, it's a pretty rare case that two such threads want to do this, so we'd prefer something that optimizes the "only one thread needs this object" case to be really fast, even if it means that the "one thread has locked this object and another one needs it" case isn't great. What are some of the best practices?

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  • Need help understanding .net ThreadPool

    - by Meredith
    I am trying to understand what ThreadPool does, I have this .NET example: class Program { static void Main() { int c = 2; // Use AutoResetEvent for thread management AutoResetEvent[] arr = new AutoResetEvent[50]; for (int i = 0; i < arr.Length; ++i) { arr[i] = new AutoResetEvent(false); } // Set the number of minimum threads ThreadPool.SetMinThreads(c, 4); // Enqueue 50 work items that run the code in this delegate function for (int i = 0; i < arr.Length; i++) { ThreadPool.QueueUserWorkItem(delegate(object o) { Thread.Sleep(100); arr[(int)o].Set(); // Signals completion }, i); } // Wait for all tasks to complete WaitHandle.WaitAll(arr); } } Does this run 50 "tasks", in groups of 2 (int c) until they all finish? Or I am not understanding what it really does.

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  • What is the best practice for accessing Model using MVVM pattern

    - by Dzenand
    I have a database that communicates with webservices with my Model (own thread) and exposes Data Objects. My UI application consists of different Views and ViewModels and Custom Controls. I'm using ServiceProvider (IServiceProvider) to access the Model and route the events to the UI thread. Communication between the ViewModels is handeled by a Messenger. Is this way to go? I was also wondering what is the best way to strucutre the DataObjects At the moment i have the DataObjects that have a hierarchy structure but does not support INotifyProperty though the children list are of type of ObservableCollection. I have no possiblity to implement notifypropertychange on the properties. I was wondering the best way of making them MVVM friendly. Implementing a partial class and adding all the properties or commands that are necessary or wrapping all the DataObjects and keep the Model list and MVVM list in sync. All thoughts and ideas are appreciated.

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  • How to fix this python error? RuntimeError: dictionary changed size during iteration

    - by aF
    Hello, it gives me this error: Exception in thread Thread-163: Traceback (most recent call last): File "C:\Python26\lib\threading.py", line 532, in __bootstrap_inner self.run() File "C:\Python26\lib\threading.py", line 736, in run self.function(*self.args, **self.kwargs) File "C:\Users\Public\SoundLog\Code\Código Python\SoundLog\SoundLog.py", line 337, in getInfo self.data1 = copy.deepcopy(Auxiliar.DataCollection.getInfo(1)) File "C:\Python26\lib\copy.py", line 162, in deepcopy y = copier(x, memo) File "C:\Python26\lib\copy.py", line 254, in _deepcopy_dict for key, value in x.iteritems(): RuntimeError: dictionary changed size during iteration while executing my python program. How can I avoid this to happen? Thanks in advance ;)

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  • Drop caches in Linux

    - by BerserkEVA
    I have an embedded Geode-based application server with 512MB RAM and I'm about to try to maximize free memory during applications workload, which uses MySQL database 5.5 with InnoDB quite aggressively. As part of the whole optimization I'd want to introduce echo 1 > /proc/sys/vm/drop_caches sleep 5 echo 0 > /proc/sys/vm/drop_caches in crontab. How often is it safe to execute something like this? Any other observation/suggestion is welcome.

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  • SwingWorker exceptions lost even when using wrapper classes

    - by Ti Strga
    I've been struggling with the usability problem of SwingWorker eating any exceptions thrown in the background task, for example, described on this SO thread. That thread gives a nice description of the problem, but doesn't discuss recovering the original exception. The applet I've been handed needs to propagate the exception upwards. But I haven't been able to even catch it. I'm using the SimpleSwingWorker wrapper class from this blog entry specifically to try and address this issue. It's a fairly small class but I'll repost it at the end here just for reference. The calling code looks broadly like try { // lots of code here to prepare data, finishing with SpecialDataHelper helper = new SpecialDataHelper(...stuff...); helper.execute(); } catch (Throwable e) { // used "Throwable" here in desperation to try and get // anything at all to match, including unchecked exceptions // // no luck, this code is never ever used :-( } The wrappers: class SpecialDataHelper extends SimpleSwingWorker { public SpecialDataHelper (SpecialData sd) { this.stuff = etc etc etc; } public Void doInBackground() throws Exception { OurCodeThatThrowsACheckedException(this.stuff); return null; } protected void done() { // called only when successful // never reached if there's an error } } The feature of SimpleSwingWorker is that the actual SwingWorker's done()/get() methods are automatically called. This, in theory, rethrows any exceptions that happened in the background. In practice, nothing is ever caught, and I don't even know why. The SimpleSwingWorker class, for reference, and with nothing elided for brevity: import java.util.concurrent.ExecutionException; import javax.swing.SwingWorker; /** * A drop-in replacement for SwingWorker<Void,Void> but will not silently * swallow exceptions during background execution. * * Taken from http://jonathangiles.net/blog/?p=341 with thanks. */ public abstract class SimpleSwingWorker { private final SwingWorker<Void,Void> worker = new SwingWorker<Void,Void>() { @Override protected Void doInBackground() throws Exception { SimpleSwingWorker.this.doInBackground(); return null; } @Override protected void done() { // Exceptions are lost unless get() is called on the // originating thread. We do so here. try { get(); } catch (final InterruptedException ex) { throw new RuntimeException(ex); } catch (final ExecutionException ex) { throw new RuntimeException(ex.getCause()); } SimpleSwingWorker.this.done(); } }; public SimpleSwingWorker() {} protected abstract Void doInBackground() throws Exception; protected abstract void done(); public void execute() { worker.execute(); } }

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  • iphone app photo upload to server from app threads

    - by user290380
    I have an app that needs to upload a least 5 photos to a server using API call available with the server. For that I am planning to use threads which will take care of photo upload and the main process can go on with the navigation of views etc. What I cant decide is whether it is OK to spawn five separate threads in iphone or use a single thread that will do the upload. In the later cases obviously it will become quite slow. Basically an HTTP POST request will be made to the server with the NSMutableURLRequest object using NSCOnnection. More threads mean more complexity and sync issues, but I can try to write code as neat as possible if it means better performance than a single thread which is simple but is a real stopper if performance is considered. Anybody with any experience in this kinda app. ??

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  • How to set up dynamically Part in MultipartRequestEntity

    - by ee_vin
    Hello, I'm using commons-httpclient-3.1 inside my android application. And I would like to know if it possible to manipulate Part (org.apache.commons.httpclient.methods.multipart.Part) dynamically? Essentially adding new FilePart and new StringPart at runtime before sending the request. Every example I've found until now suppose that you know how many fields you are dealing with. Ex: File f = new File("/path/fileToUpload.txt"); PostMethod filePost = new PostMethod("http://host/some_path"); Part[] parts = { new StringPart("param_name", "value"), new FilePart(f.getName(), f) }; filePost.setRequestEntity( new MultipartRequestEntity(parts, filePost.getParams()) ); HttpClient client = new HttpClient(); int status = client.executeMethod(filePost); code from http://hc.apache.org/httpclient-3.x/apidocs/org/apache/commons/httpclient/methods/multipart/MultipartRequestEntity.html Android specific thread: http://groups.google.com/group/android-developers/browse_thread/thread/0f9e17bbaf50c5fc Thank you

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  • Threading errors with Application.LoadComponent (key already exists)

    - by Kellls
    MSDN says that public static members of System.Windows.Application are thread safe. But when I try to run my app with multiple threads I get the following exception: ArgumentException: An entry with the same key already exists. at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) at System.Collections.Generic.SortedList`2.Add(TKey key, TValue value) at System.IO.Packaging.Package.AddIfNoPrefixCollisionDetected(ValidatedPartUri partUri, PackagePart part) at System.IO.Packaging.Package.GetPartHelper(Uri partUri) at System.IO.Packaging.Package.GetPart(Uri partUri) at System.Windows.Application.GetResourceOrContentPart(Uri uri) at System.Windows.Application.LoadComponent(Uri resourceLocator, Boolean bSkipJournaledProperties) at System.Windows.Application.LoadComponent(Uri resourceLocator) The application works fine on a single thread and even on two or three. When I get up past 5 then I get the error every time. Am I doing something wrong? What can I do to fix this?

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  • ProgressBar isn't updating

    - by Nuru Salihu
    I have a progressbar that that is show progress returned by the backgroundworker do_dowork event like below . if (ftpSourceFilePath.Scheme == Uri.UriSchemeFtp) { FtpWebRequest objRequest = (FtpWebRequest)FtpWebRequest.Create(ftpSourceFilePath); NetworkCredential objCredential = new NetworkCredential(userName, password); objRequest.Credentials = objCredential; objRequest.Method = WebRequestMethods.Ftp.DownloadFile; FtpWebResponse objResponse = (FtpWebResponse)objRequest.GetResponse(); StreamReader objReader = new StreamReader(objResponse.GetResponseStream()); int len = 0; int iProgressPercentage = 0; FileStream objFS = new FileStream((cd+"\\VolareUpdate.rar"), FileMode.Create, FileAccess.Write, FileShare.Read); while ((len = objReader.BaseStream.Read(buffer, 0, buffer.Length)) > 0) { objFS.Write(buffer, 0, len); iRunningByteTotal += len; double dIndex = (double)(iRunningByteTotal); double dTotal = (double)buffer.Length; double dProgressPercentage = (dIndex / dTotal); iProgressPercentage = (int)(dProgressPercentage); if (iProgressPercentage > 100) { iProgressPercentage = 100; } bw.ReportProgress(iProgressPercentage); } } However, my progressbar does not update. While searching , i was told the UI thread is being blocked and then i thought may be passing the progress outside the loop will do the trick. then i change to this if (ftpSourceFilePath.Scheme == Uri.UriSchemeFtp) { FtpWebRequest objRequest = (FtpWebRequest)FtpWebRequest.Create(ftpSourceFilePath); NetworkCredential objCredential = new NetworkCredential(userName, password); objRequest.Credentials = objCredential; objRequest.Method = WebRequestMethods.Ftp.DownloadFile; FtpWebResponse objResponse = (FtpWebResponse)objRequest.GetResponse(); StreamReader objReader = new StreamReader(objResponse.GetResponseStream()); int len = 0; int iProgressPercentage = 0; FileStream objFS = new FileStream((cd+"\\VolareUpdate.rar"), FileMode.Create, FileAccess.Write, FileShare.Read); while ((len = objReader.BaseStream.Read(buffer, 0, buffer.Length)) > 0) { objFS.Write(buffer, 0, len); iRunningByteTotal += len; double dIndex = (double)(iRunningByteTotal); double dTotal = (double)buffer.Length; double dProgressPercentage = (dIndex / dTotal); iProgressPercentage = (int)(dProgressPercentage); if (iProgressPercentage > 100) { iProgressPercentage = 100; } // System.Threading.Thread.Sleep(2000); iProgressPercentage++; // SetText("F", true); } bw.ReportProgress(iProgressPercentage); progressBar.Refresh(); } However still didn't help. When i put break point in my workerprogresschanged event, it show the progressbar.value however does not update. I tried progressbar.update(0, i also tried sleeping the thread for a while in the loop still didn't help. Please any suggestion/help would be appreciated .

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  • Android: how to update UI dynamically?

    - by pandre
    I have an Android app and I need to change UI dynamically: ex: when user presses a button, I want to change the current activity's views and, as in some cases there are a lot of views involved, I need to display a ProgressDialog. I have been using an AsyncTask, but I think that it is not the best solution, because AsyncTask's doInBackground runs a different thread, so I can't update UI from there - I have to use runOnUiThread, which runs the code in the UI Thread, but freezes the progress dialog that is shown. I guess there should be more people with similar issues, as updating UI while displaying a ProgressDialog seems to be something done regularly by applications. So does anyone have a solution to this?

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  • Is it possible to use instanceof when passing objects between Threads?

    - by Risser
    I've run into an issue where instanceof works, and then it doesn't. Going into details is difficult, but I think this might be the problem: Reading this: http://www.theserverside.com/news/thread.tss?thread_id=40229 (search for Thread.currentThread), it seems to imply that, even if the two objects are the same class, if you pass them between threads with different class loaders, instanceof (and isAssignableFrom) might still fail. This certainly would explain the behavior I'm having, but I was wondering if anyone could verify it? (I wish the article linked at the beginning of the discussion was still available, but it doesn't seem like it is.) Thanks, Peter

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  • Make all changes by a user reversible on linux

    - by Darokthar
    Is it possible to safe all changes a user does in his home directory? The idea is to be able to recover a home directory if a file is deleted or overwritten. My problem is having an old family member (80+ years) who wants to learn how to use a computer. For me it would be easier to recover the home directory from any abuse or mistakes that the user might do. Is there an easy solution, which is quite failsafe?

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  • Select calls seems to not time out.

    - by martsbradley
    HI Folks, I have a threaded C++ program where up to three threads are calling select on a three separate socket descriptors waiting for data to become available. Each thread handles one socket and adds it to the readfds with a timeout of 300 seconds. After select returns if there is data available I'm calling recv to read it. Is there anything that I need to be aware of with winsock and threads because for some reason after a number of hours the select calls all seem to be not timing out. Can a multi threaded program select from a number of threads without issue? I know that I should have one thread listening to all three sockets however that would be a large change for this app and I'm only looking to apply a bug fix. cheers, Martin.

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  • How to update the progress bar in runtime using c#

    - by karthik
    I am using the below code to update my progress bar. ProgressBar.Visible = true; ProgressBar.Minimum = 1; ProgressBar.Maximum = PortCount; ProgressBar.Value = 1; ProgressBar.Step = 1; int intdata = 5; for (int x = 1; x <= intdata; x++) { ProgressBar.PerformStep(); } MessageBox.Show("Done"); But, it is not getting updated during runtime. Is it because the progress bar is in the same thread. If so, how to update this progress from another thread. Help...

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  • YouTube app failes to open up when launched.

    - by user354738
    Below logs gives any clue ? The app just opens up (we could just see the tite of the app as YouTube and it goes back to launcher tray immd.) cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.google.android.youtube/.HomeActivity } 05-31 14:06:41.655: INFO/ActivityManager(1102): Start proc com.google.android.youtube for activity com.google.android.youtube/.HomeActivity: pid=2977 uid=10041 gids={3003} 05-31 14:06:41.655: DEBUG/KeyguardViewMediator(1102): setHidden false 05-31 14:06:41.796: INFO/foo(1102): ********** resuming: 1144012408 05-31 14:06:41.897: INFO/ActivityThread(2977): Publishing provider com.google.android.youtube.SuggestionProvider: com.google.android.youtube.suggest.SuggestionProvider 05-31 14:06:41.960: INFO/YouTube(2977): Distribution channel:mvapp-android-google 05-31 14:06:42.116: INFO/AndroidRuntime(2977): AndroidRuntime onExit calling exit(-42) 05-31 14:06:42.116: INFO/dalvikvm(2977): In threadExitCheck 0xbdb0 05-31 14:06:42.116: ERROR/dalvikvm(2977): Native thread exited without telling us 05-31 14:06:42.116: ERROR/dalvikvm(2977): Native thread 2977 status: 7 05-31 14:06:42.124: DEBUG/KeyguardViewMediator(1102): setHidden false 05-31 14:06:42.139: INFO/ActivityManager(1102): Process com.google.android.youtube (pid 2977) has died

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  • How can I add similar functionality to a number of methods in java?

    - by Roman
    I have a lot of methods for logging, like logSomeAction, logAnotherAction etc. Now I want all these methods make a small pause after printing messages (Thread.sleep). If I do it manually, I would do something like this: //before: public static void logSomeAction () { System.out.println (msg(SOME_ACTION)); } //after: public static void logSomeAction () { System.out.println (msg(SOME_ACTION)); try { Thread.sleep (2000); } catch (InterruptedException ignored) { } } I remember that Java has proxy classes and some other magic-making tools. Is there any way avoid copy-n-pasting N sleep-blocks to N logging methods?

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  • How do I write object classes effectively when dealing with table joins?

    - by Chris
    I should start by saying I'm not now, nor do I have any delusions I'll ever be a professional programmer so most of my skills have been learned from experience very much as a hobby. I learned PHP as it seemed a good simple introduction in certain areas and it allowed me to design simple web applications. When I learned about objects, classes etc the tutor's basic examnples covered the idea that as a rule of thumb each database table should have its own class. While that worked well for the photo gallery project we wrote, as it had very simple mysql queries, it's not working so well now my projects are getting more complex. If I require data from two separate tables which require a table join I've instead been ignoring the class altogether and handling it on a case by case basis, OR, even worse been combining some of the data into the class and the rest as a separate entity and doing two queries, which to me seems inefficient. As an example, when viewing content on a forum I wrote, if you view a thread, I retrieve data from the threads table, the posts table and the user table. The queries from the user and posts table are retrieved via a join and not instantiated as an object, whereas the thread data is called using my Threads class. So how do I get from my current state of affairs to something a little less 'stupid', for want of a better word. Right now I have a DB class that deals with connection and escaping values etc, a parent db query class that deals with the common queries and methods, and all of the other classes (Thread, Upload, Session, Photo and ones thats aren't used Post, User etc ) are children of that. Do I make a big posts class that has the relevant extra attributes that I retrieve from the users (and potentially threads) table? Do I have separate classes that populate each of their relevant attributes with a single query? If so how do I do that? Because of the way my classes are written, based on what I was taught, my db update row method, or insert method both just take the attributes as an array and update all of that, if I have extra attributes from other db tables in each class then how do I rewrite those methods as obbiously updating automatically like that would result in errors? In short I think my understanding is limited right now and I'd like some pointers when it comes to the fundamentals of how to write more complex classes.

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  • What is the effect of final variable declaration in methods?

    - by Finbarr
    Classic example of a simple server: class ThreadPerTaskSocketServer { public static void main(String[] args) throws IOException { ServerSocket socket = new ServerSocket(80); while (true) { final Socket connection = socket.accept(); Runnable task = new Runnable() { public void run() { handleRequest(connection); } }; new Thread(task).start(); } } } Why should the Socket be declared as final? Is it because the new Thread that handles the request could refer back to the socket variable in the method and cause some sort of ConcurrentModificationException?

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  • How can I transfer a user state of a win7 machine that won't boot?

    - by askvictor
    I have a windows 7 machine that won't boot completely, even in safe mode. I want to re-image the machine using a generic software image, but would like to keep the user data (including settings etc) that are on there ala Windows Easy Transfer. I can mount the hard disk on another machine - can I use Easy Transfer to transfer the user state of an account on the non-booted OS? Or do I need explore USMT?

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