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  • Grails/Spring HttpServletRequest synchronization

    - by Jeff Storey
    I was writing a simple Grails app and I have a spot in a gsp where one of my java beans in modified. <g:each in="${myList}" status="i" var="myVar"> // if the user performs some view action, update one of the myVar elements </g:each> This works, but I don't think it's quite threadsafe. myList is an http request variable but in cases of pages that use ajax (or other client side manipulations), it is possible for two threads to be modifying the same request scope variable The Spring AbstractController class provides a setSynchronizeOnSession method. Does grails provide any equivalent functionality? If not, what's the best way to protect this non-threadsafe mutation? thanks, Jeff

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  • Is it possible to prevent out-of-order execution by using single volatile

    - by Yan Cheng CHEOK
    By referring article, it is using a pair of volatile to prevent out-of-order execution. I was wondering, is it possible to prevent it using single volatile? void fun_by_thread_1() { this.isNuclearFactory = true; this.factory = new NuclearFactory(); } void fun_by_thread_2() { Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } // If out-of-order execution happens, _factory might // be NuclearFactory instance. _factory.operate(); } Factory factory = new FoodFactory(); volatile boolean isNuclearFactory = false; The reason I ask, is because I have a single guard flag (similar to isNuclearFactory flag), to guard against multiple variables (similar to many Factory). I do not wish to mark all the Factory as volatile. Or, shall I fall into the following solution? void fun_by_thread_1() { try { writer.lock(); this.isNuclearFactory = true; this.factory = new NuclearFactory(); } finally { writer.unlock(); } } void fun_by_thread_2() { try { reader.lock(); Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } } finally { reader.unlock(); } _factory.operate(); } Factory factory = new FoodFactory(); boolean isNuclearFactory = false; P/S: I know instanceof. Factory is just an example to demonstrate of out-of-order problem.

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  • SQLserver multithreaded locking with TABLOCKX

    - by WilfriedVS
    I have a table "tbluser" with 2 fields: userid = integer (autoincrement) user = nvarchar(100) I have a multithreaded/multi server application that uses this table. I want to accomplish the following: Guarantee that field user is unique in my table Guarantee that combination userid/user is unique in each server's memory I have the following stored procedure: CREATE PROCEDURE uniqueuser @user nvarchar(100) AS BEGIN BEGIN TRAN DECLARE @userID int SET nocount ON SET @userID = (SELECT @userID FROM tbluser WITH (TABLOCKX) WHERE [user] = @user) IF @userID <> '' BEGIN SELECT userID = @userID END ELSE BEGIN INSERT INTO tbluser([user]) VALUES (@user) SELECT userID = SCOPE_IDENTITY() END COMMIT TRAN END Basically the application calls the stored procedure and provides a username as parameter. The stored procedure either gets the userid or insert the user if it is a new user. Am I correct to assume that the table is locked (only one server can insert/query)?

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  • Why .NET does not allow cross-thread operations?

    - by RHaguiuda
    This question is not about what is a cross-thread operation, and how to avoid it, but why internal mechanics of .NET framework does not allow a cross-thread operation. I can`t understand why a SerialPort DataReceived event cannot update a simple text box on my form and why using delegates this is possible?

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  • How do you pass a BitmapImage from a background thread to the UI thread in WPF?

    - by DanM
    I have a background thread that generates a series of BitmapImage objects. Each time the background thread finishes generating a bitmap, I would like to show this bitmap to the user. The problem is figuring out how to pass the BitmapImage from the background thread to the UI thread. This is an MVVM project, so my view has an Image element: <Image Source="{Binding GeneratedImage}" /> My view-model has a property GeneratedImage: private BitmapImage _generatedImage; public BitmapImage GeneratedImage { get { return _generatedImage; } set { if (value == _generatedImage) return; _generatedImage= value; RaisePropertyChanged("GeneratedImage"); } } My view-model also has the code that creates the background thread: public void InitiateGenerateImages(List<Coordinate> coordinates) { ThreadStart generatorThreadStarter = delegate { GenerateImages(coordinates); }; var generatorThread = new Thread(generatorThreadStarter); generatorThread.ApartmentState = ApartmentState.STA; generatorThread.IsBackground = true; generatorThread.Start(); } private void GenerateImages(List<Coordinate> coordinates) { foreach (var coordinate in coordinates) { var backgroundThreadImage = GenerateImage(coordinate); // I'm stuck here...how do I pass this to the UI thread? } } I'd like to somehow pass backgroundThreadImage to the UI thread, where it will become uiThreadImage, then set GeneratedImage = uiThreadImage so the view can update. I've looked at some examples dealing with the WPF Dispatcher, but I can't seem to come up with an example that addresses this issue. Please advise.

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  • Java marshaller performance

    - by cbz
    Hi, I've used JAXB Marshaller as well as my own marshaller for marshalling pure java bean objects into XML. It has been observed that both of them require almost same time to marshal. The performance is not acceptable and needs to be improved. What are possible ways where we can improve performance of marshaller? Like threading?

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  • How do I use SDl_Threads properly?

    - by Anoymonous
    I am new to threads,SDL and how graphic work in general. I've been looking through all of LazyFoo's SDL tutorials, and had helped me greatly. But in his tutorials about multi threading, he commented that you should never use video functions in separate threads, or might cause problem. I am curious how it should be done, as I still have a vague understanding of graphics and threads. As one of my projects is a shoot'em up, I was wondering if I should create one thread that displays all the graphics, one threads receives all the player input for his ship, and another thread for the enemy AI. If this is NOT how it should be done, (I think it's wrong) does anyone have any advice of how graphics should be implemented with user input and enemy AI with threads? For the Lazyfoo's tutorials, this is the link: http://lazyfoo.net/SDL_tutorials/

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  • Thread-safe data structure design

    - by Inso Reiges
    Hello, I have to design a data structure that is to be used in a multi-threaded environment. The basic API is simple: insert element, remove element, retrieve element, check that element exists. The structure's implementation uses implicit locking to guarantee the atomicity of a single API call. After i implemented this it became apparent, that what i really need is atomicity across several API calls. For example if a caller needs to check the existence of an element before trying to insert it he can't do that atomically even if each single API call is atomic: if(!data_structure.exists(element)) { data_structure.insert(element); } The example is somewhat awkward, but the basic point is that we can't trust the result of "exists" call anymore after we return from atomic context (the generated assembly clearly shows a minor chance of context switch between the two calls). What i currently have in mind to solve this is exposing the lock through the data structure's public API. This way clients will have to explicitly lock things, but at least they won't have to create their own locks. Is there a better commonly-known solution to these kinds of problems? And as long as we're at it, can you advise some good literature on thread-safe design? EDIT: I have a better example. Suppose that element retrieval returns either a reference or a pointer to the stored element and not it's copy. How can a caller be protected to safely use this pointer\reference after the call returns? If you think that not returning copies is a problem, then think about deep copies, i.e. objects that should also copy another objects they point to internally. Thank you.

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  • Java - when to use notify or notifyAll?

    - by mdma
    Why does java.lang.Object have two notify methods - notify and notifyAll? It seems that notifyAll does at least everything notify does, so why not just use notifyAll all the time? If notifyAll is used instead of notify, is the program still correct, and vice versa? What influences the choice between these two methods?

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  • call multiple c++ functions in python using threads

    - by wiso
    Suppose I have a C(++) function taking an integer, and it is bound to (C)python with python api, so I can call it from python: import c_module c_module.f(10) now, I want to parallelize it. The problem is: how does the GIL work in this case? Suppose I have a queue of numbers to be processed, and some workers (threading.Thread) working in parallel, each of them calling c_module.f(number) where number is taken from a queue. The difference with the usual case, when GIL lock the interpreter, is that now you don't need the interpreter to evaluate c_module.f because it is compiled. So the question is: in this case the processing is really parallel?

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  • Thread Blocks During Call

    - by user578875
    I have a serious problem, I'm developing an application that mesures on call time during a call; the problem presents when, with the phone on the ear, the thread that the timer has, blocks and no longer responds before taking off my ear. The next log shows the problem. 01-11 16:14:19.607 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:20.607 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:21.607 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:22.597 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:23.608 14558 14566 I Estado : postDelayed Async Service 01-11 16:14:24.017 1106 1106 D iddd : select() < 0, Probably a handled signal: Interrupted system call 01-11 16:14:24.607 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:05.500 1106 1106 D iddd : select() < 0, Probably a handled signal: Interrupted system call 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service 01-11 16:18:06.026 14558 14566 I Estado : postDelayed Async Service I've been trying with Services, Timers, Threads, AyncTasks and they all present the same problem. My Code: @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); setContentView(R.layout.main); HangUpService.setMainActivity(this); objHangUpService = new Intent(this, HangUpService.class); Runnable rAccion = new Runnable() { public void run() { TelephonyManager tm = (TelephonyManager)getSystemService(TELEPHONY_SERVICE); tm.listen(mPhoneListener, PhoneStateListener.LISTEN_CALL_STATE); objVibrator = (Vibrator) getSystemService(getApplicationContext().VIBRATOR_SERVICE); final ListView lstLlamadas = (ListView) findViewById(R.id.lstFavoritos); final EditText txtMinutos = (EditText) findViewById(R.id.txtMinutos); final EditText txtSegundos = (EditText) findViewById(R.id.txtSegundos); ArrayList<Contacto> cContactos = new ArrayList<Contacto>(); ContactoAdapter caContactos = new ContactoAdapter(HangUp.this, R.layout.row,cContactos); Cursor curContactos = getContentResolver().query( ContactsContract.Contacts.CONTENT_URI, null, null, null, ContactsContract.Contacts.TIMES_CONTACTED + " DESC"); while (curContactos.moveToNext()){ String strNombre = curContactos.getString(curContactos.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME)); String strID = curContactos.getString(curContactos.getColumnIndex(ContactsContract.Contacts._ID)); String strHasPhone=curContactos.getString(curContactos.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER)); String strStarred=curContactos.getString(curContactos.getColumnIndex(ContactsContract.Contacts.STARRED)); if (Integer.parseInt(strHasPhone) > 0 && Integer.parseInt(strStarred) ==1 ) { Cursor CursorTelefono = getContentResolver().query( ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = " + strID, null, null); while (CursorTelefono.moveToNext()) { String strTipo=CursorTelefono.getString(CursorTelefono.getColumnIndex(ContactsContract.CommonDataKinds.Phone.TYPE)); String strTelefono=CursorTelefono.getString(CursorTelefono.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER)); strNumero=strTelefono; String args[]=new String[1]; args[0]=strNumero; Cursor CursorCallLog = getContentResolver().query( android.provider.CallLog.Calls.CONTENT_URI, null, android.provider.CallLog.Calls.NUMBER + "=?", args, android.provider.CallLog.Calls.DATE+ " DESC"); if (Integer.parseInt(strTipo)==2) { caContactos.add( new Contacto( strNombre, strTelefono ) ); } } CursorTelefono.close(); } } curContactos.close(); lstLlamadas.setAdapter(caContactos); lstLlamadas.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView a, View v, int position, long id) { Contacto mContacto=(Contacto)lstLlamadas.getItemAtPosition(position); i = new Intent(HangUp.this, Llamada.class); Log.i("Estado","Declaro Intent"); Bundle bundle = new Bundle(); bundle.putString("telefono", mContacto.getTelefono()); i.putExtras(bundle); startActivityForResult(i,SUB_ACTIVITY_ID); Log.i("Estado","Inicio Intent"); blActivo=true; try { String strMinutos=txtMinutos.getText().toString(); String strSegundos=txtSegundos.getText().toString(); if(!strMinutos.equals("") && !strSegundos.equals("")){ int Tiempo = ( (Integer.parseInt(txtMinutos.getText().toString())*60) + Integer.parseInt(txtSegundos.getText().toString()) )* 1000; handler.removeCallbacks(rVibrate); cTime = System.currentTimeMillis(); cTime=cTime+Tiempo; objHangUpAsync = new HangUpAsync(cTime,objVibrator,objPowerManager,objKeyguardLock); objHangUpAsync.execute(); objPowerManager.userActivity(Tiempo+3000, true); objHangUpService.putExtra("cTime", cTime); //startService(objHangUpService); } catch (Exception e) { e.printStackTrace(); } finally { } } }); } }; } AsyncTask: @Override protected String doInBackground(String... arg0) { blActivo = true; mWakeLock = objPowerManager.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Tag"); objKeyguardLock.disableKeyguard(); Log.i("Estado", "Entro a doInBackground"); timer.scheduleAtFixedRate( new TimerTask() { public void run() { if (blActivo){ if (cTime blActivo=false; objVibrator.vibrate(1000); Log.i("Estado","Vibrar desde Async"); this.cancel(); }else{ try{ mWakeLock.acquire(); mWakeLock.release(); Log.i("Estado","postDelayed Async Service"); }catch(Exception e){ Log.i("Estado","Error: " + e.getMessage()); } } } } }, 0, INTERVAL); return null; }

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  • Pointers to threads

    - by viswanathan
    Suppose i have pointer to a thread like this CWinThread *m_pThread = AfxBeginThread(StartThread, this, THREAD_PRIORITY_NORMAL, 0, 0); Now in my StartThread function assume i did all operations and the function returned like this UINT CClassThread::StartThread(LPVOID pVoid) { return true; } Will my m_pThread be invalid when the return statement is executed?

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  • Bluetooth in Java Mobile: Handling connections that go out of range

    - by Albus Dumbledore
    I am trying to implement a server-client connection over the spp. After initializing the server, I start a thread that first listens for clients and then receives data from them. It looks like that: public final void run() { while (alive) { try { /* * Await client connection */ System.out.println("Awaiting client connection..."); client = server.acceptAndOpen(); /* * Start receiving data */ int read; byte[] buffer = new byte[128]; DataInputStream receive = client.openDataInputStream(); try { while ((read = receive.read(buffer)) > 0) { System.out.println("[Recieved]: " + new String(buffer, 0, read)); if (!alive) { return; } } } finally { System.out.println("Closing connection..."); receive.close(); } } catch (IOException e){ e.printStackTrace(); } } } It's working fine for I am able to receive messages. What's troubling me is how would the thread eventually die when a device goes out of range? Firstly, the call to receive.read(buffer) blocks so that the thread waits until it receives any data. If the device goes out of range, it would never proceed onward to check if meanwhile it has been interrupted. Secondly, it would never close the connection, i.e. the server would not accept the device once it goes back in range. Thanks! Any ideas would be highly appreciated! Merry Christmas!

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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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  • 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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  • WCF Service with callbacks coming from background thread?

    - by Mark Struzinski
    Here is my situation. I have written a WCF service which calls into one of our vendor's code bases to perform operations, such as Login, Logout, etc. A requirement of this operation is that we have a background thread to receive events as a result of that action. For example, the Login action is sent on the main thread. Then, several events are received back from the vendor service as a result of the login. There can be 1, 2, or several events received. The background thread, which runs on a timer, receives these events and fires an event in the wcf service to notify that a new event has arrived. I have implemented the WCF service in Duplex mode, and planned to use callbacks to notify the UI that events have arrived. Here is my question: How do I send new events from the background thread to the thread which is executing the service? Right now, when I call OperationContext.Current.GetCallbackChannel<IMyCallback>(), the OperationContext is null. Is there a standard pattern to get around this? I am using PerSession as my SessionMode on the ServiceContract. UPDATE: I thought I'd make my exact scenario clearer by demonstrating how I'm receiving events from the vendor code. My library receives each event, determines what the event is, and fires off an event for that particular occurrence. I have another project which is a class library specifically for connecting to the vendor service. I'll post the entire implementation of the service to give a clearer picture: [ServiceBehavior( InstanceContextMode = InstanceContextMode.PerSession )] public class VendorServer:IVendorServer { private IVendorService _vendorService; // This is the reference to my class library public VendorServer() { _vendorServer = new VendorServer(); _vendorServer.AgentManager.AgentLoggedIn += AgentManager_AgentLoggedIn; // This is the eventhandler for the event which arrives from a background thread } public void Login(string userName, string password, string stationId) { _vendorService.Login(userName, password, stationId); // This is a direct call from the main thread to the vendor service to log in } private void AgentManager_AgentLoggedIn(object sender, EventArgs e) { var agentEvent = new AgentEvent { AgentEventType = AgentEventType.Login, EventArgs = e }; } } The AgentEvent object contains the callback as one of its properties, and I was thinking I'd perform the callback like this: agentEvent.Callback = OperationContext.Current.GetCallbackChannel<ICallback>(); How would I pass the OperationContext.Current instance from the main thread into the background thread?

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  • Using a Cross Thread Boolean to Abort Thread

    - by Jon
    Possible Duplicate: Can a C# thread really cache a value and ignore changes to that value on other threads? Lets say we have this code: bool KeepGoing = true; DataInThread = new Thread(new ThreadStart(DataInThreadMethod)); DataInThread.Start(); //bla bla time goes on KeepGoing = false; private void DataInThreadMethod() { while (KeepGoing) { //Do stuff } } } Now the idea is that using the boolean is a safe way to terminate the thread however because that boolean exists on the calling thread does that cause any issue? That boolean is only used on the calling thread to stop the thread so its not like its being used elsewhere

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  • Is single float assignment an atomic operation on the iPhone?

    - by iter
    I assume that on a 32-bit device like the iPhone, assigning a short float is an atomic, thread-safe operation. I want to make sure it is. I have a C function that I want to call from an Objective-C thread, and I don't want to acquire a lock before calling it: void setFloatValue(float value) { globalFloat = value; }

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  • Producer and Consumer Threads Hang

    - by user972425
    So this is my first foray into threads and thus far it is driving me insane. My problem seems to be some kind of synchronization error that causes my consumer thread to hang. I've looked at other code and just about everything I could find and I can't find what my error is. There also seems to be a discrepancy between the code being executed in Eclipse and via javac in the command line. Intention - Using a bounded buffer (with 1000 slots) create and consume 1,000,000 doubles. Use only notify and wait. Problem - In Eclipse the consumer thread will occasionally hang around 940,000 iterations, but other times completes. In the command line the consumer thread always hangs. Output - Eclipse - Successful Producer has produced 100000 doubles. Consumer has consumed 100000 doubles. Producer has produced 200000 doubles. Consumer has consumed 200000 doubles. Producer has produced 300000 doubles. Consumer has consumed 300000 doubles. Producer has produced 400000 doubles. Consumer has consumed 400000 doubles. Producer has produced 500000 doubles. Consumer has consumed 500000 doubles. Producer has produced 600000 doubles. Consumer has consumed 600000 doubles. Producer has produced 700000 doubles. Consumer has consumed 700000 doubles. Producer has produced 800000 doubles. Consumer has consumed 800000 doubles. Producer has produced 900000 doubles. Consumer has consumed 900000 doubles. Producer has produced 1000000 doubles. Producer has produced all items. Consumer has consumed 1000000 doubles. Consumer has consumed all items. Exitting Output - Command Line/Eclipse - Unsuccessful Producer has produced 100000 doubles. Consumer has consumed 100000 doubles. Producer has produced 200000 doubles. Consumer has consumed 200000 doubles. Producer has produced 300000 doubles. Consumer has consumed 300000 doubles. Producer has produced 400000 doubles. Consumer has consumed 400000 doubles. Producer has produced 500000 doubles. Consumer has consumed 500000 doubles. Producer has produced 600000 doubles. Consumer has consumed 600000 doubles. Producer has produced 700000 doubles. Consumer has consumed 700000 doubles. Producer has produced 800000 doubles. Consumer has consumed 800000 doubles. Producer has produced 900000 doubles. Consumer has consumed 900000 doubles. Producer has produced 1000000 doubles. Producer has produced all items. At this point it just sits and hangs. Any help you can provide about where I might have misstepped is greatly appreciated. Code - Producer thread import java.text.DecimalFormat;+ " doubles. Cumulative value of generated items= " + temp) import java.util.*; import java.io.*; public class producer implements Runnable{ private buffer produceBuff; public producer (buffer buff){ produceBuff = buff; } public void run(){ Random random = new Random(); double temp = 0, randomElem; DecimalFormat df = new DecimalFormat("#.###"); for(int i = 1; i<=1000000; i++) { randomElem = (Double.parseDouble( df.format(random.nextDouble() * 100.0))); try { produceBuff.add(randomElem); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } temp+= randomElem; if(i%100000 == 0) {produceBuff.print("Producer has produced "+ i ); } } produceBuff.print("Producer has produced all items."); } } Consumer thread import java.util.*; import java.io.*; public class consumer implements Runnable{ private buffer consumBuff; public consumer (buffer buff){ consumBuff = buff; } public void run(){ double temp = 0; for(int i = 1; i<=1000000; i++) { try { temp += consumBuff.get(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } if(i%100000 == 0) {consumBuff.print("Consumer has consumed "+ i ); //if(i>999000) //{System.out.println("Consuming item " + i);} } consumBuff.print("Consumer has consumed all items."); } } Buffer/Main import java.util.*; import java.io.*; public class buffer { private double buff[]; private int addPlace; private int getPlace; public buffer(){ buff = new double[1000]; addPlace = 0; getPlace = 0; } public synchronized void add(double add) throws InterruptedException{ if((addPlace+1 == getPlace) ) { try { wait(); } catch (InterruptedException e) {throw e;} } buff[addPlace] = add; addPlace = (addPlace+1)%1000; notify(); } public synchronized double get()throws InterruptedException{ if(getPlace == addPlace) { try { wait(); } catch (InterruptedException e) {throw e;} } double temp = buff[getPlace]; getPlace = (getPlace+1)%1000; notify(); return temp; } public synchronized void print(String view) { System.out.println(view); } public static void main(String args[]){ buffer buf = new buffer(); Thread produce = new Thread(new producer(buf)); Thread consume = new Thread(new consumer(buf)); produce.start(); consume.start(); try { produce.join(); consume.join(); } catch (InterruptedException e) {return;} System.out.println("Exitting"); } }

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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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  • simple process rollback question

    - by OckhamsRazor
    hi folks! while revising for an exam, i came across this simple question asking about rollbacks in processes. i understand how rollbacks occur, but i need some validation on my answer. The question: my confusion results from the fact that there is interprocess communication between the processes. does that change anything in terms of where to rollback? my answer would be R13, R23, R32 and R43. any help is greatly appreciated! thanks!

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  • java GC periodically enters into several full GC cycles

    - by Peter
    Environment: sun JDK 1.6.0_16 vm settings: -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -Xms1024 -Xmx1024M -XX:MaxNewSize=448m -XX:NewSize=448m -XX:SurvivorRatio=4(6 also checked) -XX:MaxPermSize=128M OS: windows server 2003 processor: 4 cores of INTEL XEON 5130, 2000 Hz my application description: high intensity of concurrent(java 5 concurrency used) operations completed each time by commit to oracle. it's about 20-30 threads run non stop, doing tasks. application runs in JBOSS web container. My GC starts work normally, I see a lot of small GCs and all that time CPU shows good load, like all 4 cores loaded to 40-50%, CPU graph is stable. Then , after 1 min of good work, CPU starts drop to 0% on 2 cores from 4, it's graph becomes unstable, goes up and down("teeth"). I see, that my threads work slower(I have monitoring), I see that GC starts produce a lot of FULL GC during that time and next 4-5 minutes this situation remains as is, then for short period of time, like 1 minute, it gets back to normal situation, but shortly after that all bad thing repeats. Question: Why I have so frequent full GC??? How to prevent that? I played with SurvivorRatio - does not help. I noticed, that application behaves normally until first FULL GC occurs, while I have enough memory. Then it runs badly. my GC LOG: starts good then long period of FULL GCs(many of them) 1027.861: [GC 942200K-623526K(991232K), 0.0887588 secs] 1029.333: [GC 803279K(991232K), 0.0927470 secs] 1030.551: [GC 967485K-625549K(991232K), 0.0823024 secs] 1030.634: [GC 625957K(991232K), 0.0763656 secs] 1033.126: [GC 969613K-632963K(991232K), 0.0850611 secs] 1033.281: [GC 649899K(991232K), 0.0378358 secs] 1035.910: [GC 813948K(991232K), 0.3540375 secs] 1037.994: [GC 967729K-637198K(991232K), 0.0826042 secs] 1038.435: [GC 710309K(991232K), 0.1370703 secs] 1039.665: [GC 980494K-972462K(991232K), 0.6398589 secs] 1040.306: [Full GC 972462K-619643K(991232K), 3.7780597 secs] 1044.093: [GC 620103K(991232K), 0.0695221 secs] 1047.870: [Full GC 991231K-626514K(991232K), 3.8732457 secs] 1053.739: [GC 942140K(991232K), 0.5410483 secs] 1056.343: [Full GC 991232K-634157K(991232K), 3.9071443 secs] 1061.257: [GC 786274K(991232K), 0.3106603 secs] 1065.229: [Full GC 991232K-641617K(991232K), 3.9565638 secs] 1071.192: [GC 945999K(991232K), 0.5401515 secs] 1073.793: [Full GC 991231K-648045K(991232K), 3.9627814 secs] 1079.754: [GC 936641K(991232K), 0.5321197 secs]

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  • How can I make a single WCF method ConcurrencyMode.Multiple when service is ConcurencyMode.Single

    - by Michael Hedgpeth
    I have a service which is defined as ConcurrencyMode.Single: [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Single, UseSynchronizationContext = false, InstanceContextMode = InstanceContextMode.PerSession, IncludeExceptionDetailInFaults = true)] public class MyService : IMyService This service provides a method to tell the client what it's currently working on: [OperationContract] string GetCurrentTaskDescription(); Is there a way to make this particular method allowable while another long-running task is running where all other methods still follow the single-threaded concurrency model?

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  • Setting the default stack size on Linux globally for the program

    - by wowus
    So I've noticed that the default stack size for threads on linux is 8MB (if I'm wrong, PLEASE correct me), and, incidentally, 1MB on Windows. This is quite bad for my application, as on a 4-core processor that means 64 MB is space is used JUST for threads! The worst part is, I'm never using more than 100kb of stack per thread (I abuse the heap a LOT ;)). My solution right now is to limit the stack size of threads. However, I have no idea how to do this portably. Just for context, I'm using Boost.Thread for my threading needs. I'm okay with a little bit of #ifdef hell, but I'd like to know how to do it easily first. Basically, I want something like this (where windows_* is linked on windows builds, and posix_* is linked under linux builds) // windows_stack_limiter.c int limit_stack_size() { // Windows impl. return 0; } // posix_stack_limiter.c int limit_stack_size() { // Linux impl. return 0; } // stack_limiter.cpp int limit_stack_size(); static volatile int placeholder = limit_stack_size(); How do I flesh out those functions? Or, alternatively, am I just doing this entirely wrong? Remember I have no control over the actual thread creation (no new params to CreateThread on Windows), as I'm using Boost.Thread.

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