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• qapps runs well but breakpoint sometimes generates segmentation fault

  - by yan bellavance

  I have a qApp that generates a segmentation fault only when a breakpoint is inserted in the code (I can put it at different places) and only after 4-5 breakpoint stops. Do I have a problem with my code or is this a DBG bug. the method is part of a QThread Class. Basically what I did is i took the mandlebrot example, and have 3 instances of it in my program. So the program would look like a mainwindow that has 3 mandlebrot widgets in it, one besides the other. Is it possible that GDB doesnt support debugging qthread subclasses that are instantiated multiple times or is it thread-unsafe to do so. I dont have any problems at run-time.

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• How to download files directly to disk on the iPhone os?

  - by favo

  Hi, I would like to download files directly from an URL to the disk using objective-c on the iPhone os. Currently I am using NSURLConnection to send a synchronousRequest, writing the returned NSData into a file. How can I change the download handling (still having the request beeing synchronous, it is already in a background thread) to write the data directly to disk, not using memory variables to store the complete content (only small parts)? A sample code would be appreciated. Thank you all in advance for your responses!

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• Unexpected cross threading issue

  - by haughtonomous

  I'm trying to do something very simple in principal, but I keep getting a cross-threading exception which has me stumped because I'm not setting out to use multiple threads. I have a Windows Forms application. It launches another Windows Forms application (using the System.Diagnostics.Process class) , and catches the Exited event when that application is closed. My application event handler then tries to copy text from the clipboard to a control on the current displayed form. At this point a Cross-threading exception is thrown. I assume that the problem is that the event from the closing application is in another thread (I'm outside my comfort zone here, so bear with me), so the question boils down to "How do I prevent this exception?" I'm somewhat constrained into having to copy from the clipboard, but I could launch the other application a different way if that would solve the problem.

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• MySQL Locks: order of unblocked threads

  - by teehoo

  I have a MySQL ISAM table being accessed my multiple php instances. Right now I'm using a WRITE lock to serialize access to this table. My question is how do I ensure that the PHP instances get served on a First-Come-First-Serve basis? Or is this the default behaviour? The official MySQL documentation doesn't mention anything about the blocked thread order for threads of the same lock type (ie multiple threads attempting a WRITE LOCK). It only mentions that a WRITER will jump to the front of the waiting queue if READERS are waiting.

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• "No row with the given identifier exists" although it DOES exist!

  - by roesslerj

  Hello all! I am using Hibernate and getting Exception in thread "main" org.hibernate.ObjectNotFoundException: No row with the given identifier exists: [<MyDbObject>#271] What is pretty weird about this error is, that the object with the given id exists in the database. I inserted the problematic record in another run of the application. If I access it in the same run (i.e. same hibernate session) there seem to be no problems retrieving the data. Just because it could be a fault of the mapping: public class ProblemClass { @ManyToOne(optional = false) private MyDbObject myDbObject; } public class MyDbObject { @OneToMany(mappedBy = "myDbObject") private List<ProblemClass> problemClasses; } I have absolutely no clue even where to look at. Any hints highly appreciated!

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• How do I fix "java.lang.OutOfMemoryError at sun.misc.Unsafe.allocateMemory(Native Method)"?

  - by Jephir

  I'm making a Java application that uses the Slick library to load images. However, on some computers, I get this error when trying to run the program: Exception in thread "main" java.lang.OutOfMemoryError at sun.misc.Unsafe.allocateMemory(Native Method) at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:99) at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:288) at org.lwjgl.BufferUtils.createByteBuffer(BufferUtils.java:60) at org.newdawn.slick.opengl.PNGImageData.loadImage(PNGImageData.java:692) at org.newdawn.slick.opengl.CompositeImageData.loadImage(CompositeImageData.java:62) at org.newdawn.slick.opengl.CompositeImageData.loadImage(CompositeImageData.java:43) My VM options are: -Djava.library.path=lib -Xms1024M -Xmx1024M -XX:PermSize=256M -XX:MaxPermSize=256M The program loads a few large images (1024 x 768 resolution) at the beginning. Any help to solve this problem would be greatly appreciated.

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• CaptureCameraDialog returns OK but does not save (Motorola ES400)

  - by Dominic

  Ok it seems like everyone in the world has issues with CaptureCameraDialog. In my case the result is OK, but when taking the photo there is a MessageBox that says "Error" that appears and disappears in the blink of an eye, then returns to my app (so I don't have time to actually read the error). It has not saved the file. It does not throw an error to my application. There is also another issue which is exactly the same as the issue talked about here (yet none of the fixes work for me). http://www.pcreview.co.uk/forums/thread-4025602.php Does anyone know how to get the "error message" that the dialogue box displays for an instant?

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• How to handle recurring execution?

  - by ShaneC

  I am trying to validate the solution I came up for what I think is a fairly typical problem. I have a service running and every 10 minutes it should do something. I've ended up with the following: private bool isRunning = true; public void Execute() { while(isRunning) { if(isRunning) { DoSomething(); m_AutoResetEvent.WaitOne(new Timespan(0, 10, 0)); } } } public void Stop() { isRunning = false; m_AutoResetEvent.Set(); } The immediate potential problems I can see is that I'm not doing any sort of locking around the isRunning modification in Stop() which gets called by another thread but I'm not sure I really need to? The worst that I think could happen is that it runs one extra cycle. Beyond that are there any obvious problems with this code? Is there a better way to solve this problem that I'm unaware of?

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• Combining RequiresSTA and Timeout attributes on a test fails

  - by Peter Lillevold

  I have a test that opens and closes a WPF Window and thus requires the STA threading apartment. To safeguard the test against the window staying open (and thus hang the test indefinitely) I wanted to use the Timeout attribute. The problem is that applying the Timeout attribute causes the test to fail on timeout regardless of whether the test works or not. Without the attribute everything works fine. My theory is that Timeout causes the test to be executed on a new thread that does not inherit the STA apartment. Is there another way to have both STA and the timeout safeguard in NUnit? My test looks something like this: [Test, RequiresSTA, Timeout(300)] public void Construct() { var window = new WindowView(); window.Loaded += (sender, args) => window.Close(); var app = new Application(); app.Run(window); try { // ...run system under test } finally { app.Shutdown(); } }

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• Invoking a superclass's class methods in Python

  - by LeafStorm

  I am working on a Flask extension that adds CouchDB support to Flask. To make it easier, I have subclassed couchdb.mapping.Document so the store and load methods can use the current thread-local database. Right now, my code looks like this: class Document(mapping.Document): # rest of the methods omitted for brevity @classmethod def load(cls, id, db=None): return mapping.Document.load(cls, db or g.couch, id) I left out some for brevity, but that's the important part. However, due to the way classmethod works, when I try to call this method, I receive the error message File "flaskext/couchdb.py", line 187, in load return mapping.Document.load(cls, db or g.couch, id) TypeError: load() takes exactly 3 arguments (4 given) I tested replacing the call with mapping.Document.load.im_func(cls, db or g.couch, id), and it works, but I'm not particularly happy about accessing the internal im_ attributes (even though they are documented). Does anyone have a more elegant way to handle this?

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• Temporary files & folders on Windows

  - by GRIGORE-TURBODISEL

  Emulating multithreading by loading a DLL multiple times (it's designed for this). Since LoadLibrary() doesn't really allow it, the DLL copies itself into a temporary file, via GetTempPath() and GetTempFileName(). It's a small file and upon thread destruction it frees the library and deletes the temporary file. Problem now is that the number of threads is configurable (maniacs can pick 50, 100, more) which basically exposes the risk of running unstable, crash and not go through the usual "delete temporary files" routine. Is it okay if I just leave those temporary files to die there? Does the OS usually clean the up by itself? Or should I write an autocleanup routine? If yes, how can I go about saving another temporary file to hold a list with those files, and not hit UAC restrictions or otherwise? Any ideas?

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• discrepancy in using AsyncTask, code is executed in weird order

  - by Pentium10

  Hello, In onCreate method I hav the following order of code objItem = new DbClass(this);//the onCreate event creates the database new PrepareAdapter1().execute();//this task uses the tables, but SQLException occures, tables doesn't exists As you see in my short code, I get a new instance of the SQLiteOpenHelper class, which does create the tables in onCreate. And after that I start an AsyncTask instance where I use the created table. But I get SQLiteException as table doesn't not exists. I am using this code in wrong way? I expect the table to be created when I launch the thread.

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• Cocos 2D v1.0.1 : Crash at changing CCMenuItemImage normal image

  - by Max

  I retrieve a crash log file, which, after XCode analysis on my archive show the problematic line of code : Date/Time: 2012-12-08 23:48:08.930 +0100 OS Version: iPhone OS 5.1.1 (9B206) Report Version: 104 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x00000000, 0x00000000 Crashed Thread: 0 Last Exception Backtrace: 0 CoreFoundation 0x31a4088f __exceptionPreprocess + 163 1 libobjc.A.dylib 0x3188b259 objc_exception_throw + 33 2 CoreFoundation 0x31a40789 +[NSException raise:format:] + 1 3 Foundation 0x374c73a3 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 91 4 Killer 0x0017ed35 -[CCSprite initWithFile:] (CCSprite.m:201) 5 Killer 0x0017e419 +[CCSprite spriteWithFile:] (CCSprite.m:93) 6 Killer 0x00123101 -[Player makeZombie] (Player.m:1363) 7 Killer 0x00105a51 -[PlayScene endOfKilling:] (PlayScene.m:1438) Which clearly indicates the second of the two following lines is crashing: NSLog(@"images %@ %@",self.zombieImage,self.zombieImageDown); [self.characterSprite setNormalImage:[CCSprite spriteWithFile:self.zombieImage]]; I know that the crash seem to happend when the user is touching the corresponding CCMeanuItemImage, is there a problem if the user is touching it, while we change the normal et selected images of it ? Is this the right manner to change its image (i do it several times during the game) ? Thanks for your ideas

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• C# Executing timed commands with varying times

  - by Gio Borje

  I have a timer control and a grid with a List of coordinates for the grid. I was wondering how I could use the timer control or any other control in order to execute code in the interval, coordinate.Time as it varies for each coordinate. Also, thread.sleep(time) is not an option for me. foreach (Coordinate coordinate in this.Macro) { coordinate.Time; coordinate.Initial; coordinate.Final; ... executecode @ coordinate.Time. }

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• Triggering Quartz job from JSF (Any front end)- How to wait for the job execution to be over

  - by Maximus

  I am developing a front end to trigger a quartz job on the fly. I have a form in the JSF page whose click action will dynamically trigger a quartz job. The job is invoked by the following statement, the job is triggered and everything works fine. scheduler.triggerJob("Job1",Scheduler.DEFAULT_GROUP,jobDataMap); From what I understand the job seems to run in a separate thread and the execution of the calling function does not wait for the job to be over. Since I am invoking the job from front end, I would like to wait till the job is over before I navigate to a different JSF page. So I can display an error message if the job fails. I would also like to display a message to the user, "Processing job, please wait.." until the job is actually over. Any ideas on how to accomplish this will be appreciated. Thanks !

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• Learning rails and AJAX. How do I load a div via ajax and then toggle hiding/showing it?

  - by Kevin L.

  I'm doing my first Ruby on Rails project. I am working on a project where the user can add a new message. Then they can add updates to this message like a thread. I've got it all written and now I'm going back and applying some AJAX. I want to show just the main message when the page first loads. Then when I click a link I want an AJAX event to fire that populates a div with all the updates to the message. Then I want this same link to toggle hiding and showing the div. I've made a submit button to fire the ajax and get back the updates using form_remote_tag. I've also created a separate link to toggle the hiding using $(div_id).toggle();. But now I'm stuck on how to combine these two things into one all purpose link. Thanks.

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• Is there an easy way in Python to wait until certain condition is true?

  - by Checkers

  I need to wait in a script until a certain number of conditions become true? I know I can roll my own eventing using condition variables and friends, but I don't want to go through all the trouble of implementing it, since some object property changes come from external thread in a wrapped C++ library (Boost.Python), so I can't just hijack __setattr__ in a class and put a condition variable there, which leaves me with either trying to create and signal a Python condition variable from C++, or wrap a native one and wait on it in Python, both of which sound fiddly, needlessly complicated and boring. Is there an easier way to do it, barring continuous polling of the condition? Ideally it would be along the lines of res = wait_until(lambda: some_predicate, timeout) if (not res): print 'timed out'

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• How can I prevent ADO from creating multiple SPIDs?

  - by stusmith

  I'm working on an application that creates a single ADO connection and keeps it open for the lifetime of the application. I have connection pooling turned off. (Please ignore the fact that this might not be best practice for the purposes of this question). If I spawn a new thread and use the exact same ADO connection, it uses a new SPID behind the scenes. Is there anyway to ensure an ADO connection always uses the same SPID, across all threads? (For reference the application is VC++ using ADO via COM to SQL Server).

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• How to call a function though Control.BeginInvoke in a signal-slot-like fashion?

  - by Dimitri C.

  I'd like a delegate that calls a function in a different thread when it is invoked. Currently, I'm using the following implementation: delegate void someFunctionDelegate(); //... someFunctionDelegate callBackFunction = someForm.SomeFunction; someForm.Invoke(someFunctionDelegate); However, I'd like a more compact form, combining both the someForm instance and the SomeForm.SomeFunction member function. I'm thinking of something like this: var callBackFunction = new AsynchronousCrossThreadDelegate(someForm, SomeForm.SomeFunction); callBackFunction(); // Should call someForm.BeginInvoke(SomeForm.SomeFunction); Is there a way to do so in C#/.NET? Update I'm looking for a solution that will work for functions with 0 or more parameters.

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• Can an application's Service ever run in a different process?

  - by kpdvx

  If an application begins a Service via bindService or startService, will this Service object ever run from a process different from that of the application? I ask because many Android example projects begin a service and communicate to them using IPC which seems wholly unnecessary considering that, according to the Android Service documentation, "... services, like other application objects, run in the main thread of their hosting process." IPC, AIDL, and the IBinder interface only seem useful if connecting to a Service started by an application other than your own. Is this a correct or fair understanding?

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• Parameter is not valid when getting image from stream

  - by duka1

  Hi guys, I have this code: MemoryStream ms = new MemoryStream(newbytes, 0, newbytes.Length); ms.Position = 0; ms.Write(newbytes, 0, newbytes.Length); Image img = Image.FromStream(ms); img.Save(@"C:\Users\gsira\Pictures\Blue hills5.jpg"); I get this error at the Image.FromStream(ms) call: System.ArgumentException: Parameter is not valid. at System.Drawing.Image.FromStream(Stream stream, Boolean useEmbeddedColorManagement, Boolean validateIma How can I resolve this? A couple of links which solve this problem (one on an MSDN thread) are broken so I am lost.

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• Code won't exit foreach block

  - by Matt

  I've got the following C# code segment that takes a list, finds objects that are ready to update, then shoves them into a temp list, deletes from the main list, and then goes on its merry way. My issue is that the foreach block, which cycles through my main list, won't exit. TempLog.Clear(); //Ensure TempLog is empty foreach (CLogger ready in PlayerLog) { if (ready.UpdateReady == true) // Record is ready to be updated in database { TempLog.Add(ready); // Add record to templog PlayerLog.Remove(ready); // Remove from playerlog } } <---- Never reaches this point if (TempLog.Count > 0) // Just check that templog isn't empty { new Thread(Update).Start(); // Run update code } I've put heaps of debugging in, and I can watch PlayerLog start at 1, TempLog at 0, then it enters the foreach loop, picks up that the record UpdateReady flag is on, TempLog goes to 1, PlayerLog goes to 0, then it just stops.. No errors, just stops.. Thanks for the help :)

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• Handling Messages in Console Apps/DLLs in C++ Win32

  - by vsimon

  I would like to have the ability to process Win32 messages in a console app and/or inside a standalone DLL. I have been able to do it in .NET with the following article and it works great in C# inside a console app and standalone DLL http://msdn.microsoft.com/en-us/magazine/cc163417.aspx Is there a way to do the equivalent with C/C++ Win32 APIs? I have tried doing RegisterClassEx(...) and CreateWindow(...) even passing in HWND_MESSAGE to hWndParent but the trouble is that after the "invisible" window is created messages are not being processed probably due to the lack of a message pump. Where would the message pump go if you had a DLL entry point? I have tried creating another thread in a DLL and put while(GetMesage(..)) there but that did not work either. Any ideas?

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• SQL Compact Edition 3.5 SP 1 - LockTimeOutException - how to debug?

  - by Bob King

  Intermittently in our app, we encounter LockTimeoutExceptions being throw from SQL CE. We've recently upgraded to 3.5 SP 1, and a number of them seem to have gone away, but we still do see them occasionally. I'm certain it's a bug in our code (which is multi-threaded) but I haven't been able to pin it down precisely. Does anyone have any good techniques for debugging this problem? The exceptions log like this (there's never a stack trace for these exceptions): SQL Server Compact timed out waiting for a lock. The default lock time is 2000ms for devices and 5000ms for desktops. The default lock timeout can be increased in the connection string using the ssce: default lock timeout property. [ Session id = 6,Thread id = 7856,Process id = 10116,Table name = Product,Conflict type = s lock (x blocks),Resource = DDL ] Our database is read-heavy, but does seldom writes, and I think I've got everything protected where it needs to be. EDIT: SQL CE already automatically uses NOLOCK http://msdn.microsoft.com/en-us/library/ms172398(sql.90).aspx

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• c++11 atomic ordering: extended total order memory_order_seq_cst for locks

  - by itaj

  There's this note in c++11 29.3-p3: [ Note: Although it is not explicitly required that S include locks, it can always be extended to an order that does include lock and unlock operations, since the ordering between those is already included in the "happens before" ordering. - end note ] What does it mean by "always"? I can understand that any certain implementation can be designed to support such an extended S. But in some general implementation that wasn't designed for it, I don't see that S can be extended so. I had sent this question to comp.std.c++ but got no answers there. http://groups.google.com/group/comp.std.c++/browse_frm/thread/5242fa70d0594d1b#

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