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  • Why is thread local storage so slow?

    - by dsimcha
    I'm working on a custom mark-release style memory allocator for the D programming language that works by allocating from thread-local regions. It seems that the thread local storage bottleneck is causing a huge (~50%) slowdown in allocating memory from these regions compared to an otherwise identical single threaded version of the code, even after designing my code to have only one TLS lookup per allocation/deallocation. This is based on allocating/freeing memory a large number of times in a loop, and I'm trying to figure out if it's an artifact of my benchmarking method. My understanding is that thread local storage should basically just involve accessing something through an extra layer of indirection, similar to accessing a variable via a pointer. Is this incorrect? How much overhead does thread-local storage typically have? Note: Although I mention D, I'm also interested in general answers that aren't specific to D, since D's implementation of thread-local storage will likely improve if it is slower than the best implementations.

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  • C# - Which is more efficient and thread safe? static or instant classes?

    - by Soni Ali
    Consider the following two scenarios: //Data Contract public class MyValue { } Scenario 1: Using a static helper class. public class Broker { private string[] _userRoles; public Broker(string[] userRoles) { this._userRoles = userRoles; } public MyValue[] GetValues() { return BrokerHelper.GetValues(this._userRoles); } } static class BrokerHelper { static Dictionary<string, MyValue> _values = new Dictionary<string, MyValue>(); public static MyValue[] GetValues(string[] rolesAllowed) { return FilterForRoles(_values, rolesAllowed); } } Scenario 2: Using an instance class. public class Broker { private BrokerService _service; public Broker(params string[] userRoles) { this._service = new BrokerService(userRoles); } public MyValue[] GetValues() { return _service.GetValues(); } } class BrokerService { private Dictionary<string, MyValue> _values; private string[] _userRoles; public BrokerService(string[] userRoles) { this._userRoles = userRoles; this._values = new Dictionary<string, MyValue>(); } public MyValue[] GetValues() { return FilterForRoles(_values, _userRoles); } } Which of the [Broker] scenarios will scale best if used in a web environment with about 100 different roles and over a thousand users. NOTE: Feel free to sugest any alternative approach.

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  • Fast single thread comet server, possible?

    - by Pepijn
    I recently encountered a few cases where a server would distribute an event stream that contains the exact same data for all listeners, such as a 'recent activity' box. It occurred to me that it is quite strange and inefficient to have a server like Apache run a thread processing and querying the database for every single comet stream containing the same data. What I would do for those global(not per user) streams is run a single thread that continuously emits data, and a new (green)thread for every new request that outputs the headers and then 'merges' into the main thread. Is it possible for one thread to serve multiple sockets, or for multiple clients to listen to the same socket? An example o = event # threads received | a b # 3 o / / # 3 - |/_/ | # 1 o c # 2 a, b | / o/ # 2 a, b o # 1 a, b, c | # connection b closed o # 1 a, c Does something like this exist? Would it work? Is it possible to do? Disclaimer: I'm not a server expert.

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  • Which thread invokes SensorEventListener.onSensorChanged

    - by Christoph Heindl
    From my records it seems that SensorEventListener.onSensorChanged callback is called by the same thread that registered the callback. I.e there must be some message-queue synchronization going on in the background which allows the activitys UI-Thread to handle the callbacks. That leads to my question: Is there a need to synchronize SensorEventListener.onSensorChanged with the activitys UI-thread, assuming that the activitys UI-thread registered the SensorEventListener? I cannot find any documentation references, but can see various examples calling invalidate() unsychronized or synchronize the entire callback. I used something along the lines of Log.i(TAG, "" + Thread.currentThread().getId()); to retrieve threading information. I'm running android 2.1 update1. Best regards, Christoph

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  • Advantage of using Thread.Start vs QueueUserWorkItem

    - by Cheeso
    In multithreaded .NET programming, what are the decision criteria for using ThreadPool.QueueUserWorkItem versus starting my own thread via new Thread() and Thread.Start()? In a server app (let's say, an ASP.NET app or a WCF service) I think the ThreadPool is always there and available. What about in a client app, like a WinForms or WPF app? Is there a cost to spin up the thread pool? If I just want 3 or 4 threads to work for a short period on some computation, is it better to QUWI or to Thread.Start().

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  • Sockets, Threads and Services in android, how to make them work together ?

    - by Spredzy
    Hi all, I am facing a probleme with threads and sockets I cant figure it out, if someone can help me please i would really appreciate. There are the facts : I have a service class NetworkService, inside this class I have a Socket attribute. I would like it be at the state of connected for the whole lifecycle of the service. To connect the socket I do it in a thread, so if the server has to timeout, it would not block my UI thread. Problem is, into the thread where I connect my socket everything is fine, it is connected and I can talk to my server, once this thread is over and I try to reuse the socket, in another thread, I have the error message Socket is not connected. Questions are : - Is the socket automatically disconnected at the end of the thread? - Is their anyway we can pass back a value from a called thread to the caller ? Thanks a lot, Here is my code public class NetworkService extends Service { private Socket mSocket = new Socket(); private void _connectSocket(String addr, int port) { Runnable connect = new connectSocket(this.mSocket, addr, port); new Thread(connect).start(); } private void _authentification() { Runnable auth = new authentification(); new Thread(auth).start(); } private INetwork.Stub mBinder = new INetwork.Stub() { @Override public int doConnect(String addr, int port) throws RemoteException { _connectSocket(addr, port); _authentification(); return 0; } }; class connectSocket implements Runnable { String addrSocket; int portSocket; int TIMEOUT=5000; public connectSocket(String addr, int port) { addrSocket = addr; portSocket = port; } @Override public void run() { SocketAddress socketAddress = new InetSocketAddress(addrSocket, portSocket); try { mSocket.connect(socketAddress, TIMEOUT); PrintWriter out = new PrintWriter(mSocket.getOutputStream(), true); out.println("test42"); Log.i("connectSocket()", "Connection Succesful"); } catch (IOException e) { Log.e("connectSocket()", e.getMessage()); e.printStackTrace(); } } } class authentification implements Runnable { private String constructFirstConnectQuery() { String query = "toto"; return query; } @Override public void run() { BufferedReader in; PrintWriter out; String line = ""; try { in = new BufferedReader(new InputStreamReader(mSocket.getInputStream())); out = new PrintWriter(mSocket.getOutputStream(), true); out.println(constructFirstConnectQuery()); while (mSocket.isConnected()) { line = in.readLine(); Log.e("LINE", "[Current]- " + line); } } catch (IOException e) {e.printStackTrace();} } }

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  • Date Range Problem

    - by ungalnanban
    I have a log file which has first few characters of every line as a timestamp. 2010-06-01 04:56:02,802 DEBUG {Thread-27} Some text message 2010-06-01 04:56:02,802 DEBUG {Thread-27} Some text message 2010-06-01 04:56:02,802 DEBUG {Thread-27} Some text message 2010-06-01 04:56:02,802 DEBUG {Thread-27} Some text message 2010-06-01 05:22:02,802 DEBUG {Thread-27} Some text message 2010-06-01 05:22:02,802 DEBUG {Thread-27} Some text message 2010-06-01 05:22:02,802 DEBUG {Thread-27} Some text message 2010-06-01 05:22:02,802 DEBUG {Thread-27} Some text message 2010-06-01 06:43:02,802 INFO {Thread-27} Some text message 2010-06-01 06:43:02,803 INFO {Thread-27} Some text message 2010-06-01 06:43:02,804 INFO {Thread-27} Some text message 2010-06-01 06:43:02,804 INFO {Thread-27} Some text message 2010-06-01 06:43:02,809 DEBUG {Thread-27} Some text message 2010-06-01 06:43:02,809 DEBUG {Thread-27} Some text message 2010-06-01 06:43:02,809 DEBUG {Thread-27} Some text message 2010-06-01 07:08:02,809 DEBUG {Thread-27} Some text message 2010-06-01 07:08:02,809 DEBUG {Thread-27} Some text message My aim to find all such lines which have the timestamp of 1 hr before the current time. How can this be achieved?

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  • java: relationship of the Runnable and Thread interfaces

    - by Karl Patrick
    I realize that the method run() must be declared because its declared in the Runnable interface. But my question comes when this class runs how is the Thread object allowed if there is no import call to a particular package? how does runnable know anything about Thread or its methods? does the Runnable interface extend the Thread class? Obviously I don't understand interfaces very well. thanks in advance. class PrimeFinder implements Runnable{ public long target; public long prime; public boolean finished = false; public Thread runner; PrimeFinder(long inTarget){ target = inTarget; if(runner == null){ runner = new Thread(this); runner.start() } } public void run(){ } }

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  • python: can't terminate a thread hung in socket.recvfrom() call

    - by Dihlofos
    Hello, everyone I cannot get a way to terminate a thread that is hung in a socket.recvfrom() call. For example, ctrl+c that should trigger KeyboardInterrupt exception can't be caught. Here is a script I've used for testing: from socket import * from threading import Thread from sys import exit class TestThread(Thread): def __init__(self,host="localhost",port=9999): self.sock = socket(AF_INET,SOCK_DGRAM) self.sock.bind((host,port)) super(TestThread,self).__init__() def run(self): while True: try: recv_data,addr = self.sock.recvfrom(1024) except (KeyboardInterrupt, SystemExit): sys.exit() if __name__ == "__main__": server_thread = TestThread() server_thread.start() while True: pass The main thread (the one that executes infinite loop) exits. However the thread that I explicitly create, keeps hanging in recvfrom(). Please, help me resolve this.

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  • Thread.sleep vs Monitor.Wait vs RegisteredWaitHandle?

    - by Royi Namir
    (the following items has different goals , but im interesting knowing how they "PAUSEd") questions Thread.sleep - Does it impact performance on a system ?does it tie up a thread with its wait ? what about Monitor.Wait ? what is the difference in the way they "wait"? do they tie up a thread with their wait ? what aboutRegisteredWaitHandle ? This method accepts a delegate that is executed when a wait handle is signaled. While it’s waiting, it doesn’t tie up a thread. so some thread are paused and can be woken by a delegate , while others just wait ? spin ? can someone please make things clearer ? edit http://www.albahari.com/threading/part2.aspx

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  • Secondary thread causes startup delay

    - by JK
    In my didFinishLaunchingWithOptions method I spawn a thread to perform some maintenance on my core data store. However, this increases the startup time by half a second. The startup view is a tableview which draws its content from the same store. If I let the thread sleep for a second, the startup time improves drastically. I would like to understand why the second thread is blocking/delaying the main thread. Is it because both are trying to access the store (The second thread has its own store coordinator and context) or another reason (e.g. dont spawn threads in didFinishLaunching)?

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  • Thread-safe blocking queue implementation on .NET

    - by Shrike
    Hello. I'm looking for an implementation of thread-safe blocking queue for .NET. By "thread-safe blocking queue" I mean: - thread-safe access to a queue where Dequeue method call blocks a thread untill other thread puts (Enqueue) some value. By the moment I'v found this one: http://www.eggheadcafe.com/articles/20060414.asp (But it's for .NET 1.1). Could someone comment/criticize correctness of this implementation. Or suggest some another one. Thanks in advance.

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  • multiple move operations and data processes in work thread

    - by younevertell
    main thread-- start workthread--StartStage(get list of positions for data process) -- move to one position -- data sampling*strong text*-- data collection--data analysis------data sampling*strong text* basically, work thread does the data sampling*strong text*-- data collection--data analysis------data sampling*strong text* loop for one positioin until press stop or target is obtained. my questions: After work thread finishs the loop for one positioin, it would end itself. now how to make the work thread moves to the next position to do the data process loop after work thread finish one position work, would not end itself until data process for all the positions are done? Thanks in advance!

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  • how to call windows paint event from child thread

    - by RAJ K
    If I am wrong then please correct me as I am new in this. I have one thread which display image captured from webcam on a windows created using CreateWindowEx() function. Now when i execute my program I can see that my paint code (in WindowProc()) in never reached (called InvalidateRect() from child thread to redraw), checked using breakpoint. Actually frame capture and display is being done in thread and I think because its in child thread and Window is in Main thread that is why its not able to call paint event. Can you help me on this

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  • Problem in creating another thread

    - by Avinash
    Hi, I am using NSThread to create different thread and displaying images in my application on a new thread instead of main thread. On main thread i am working with a table view which is displaying data from XML file, In the same view I am displaying images below. But, displaying images on new thread is not working properly. Did i made any mistake in creating Here below is my code. Please help me its urgent. Thanks in advance...................... - (void)viewDidLoad { [super viewDidLoad]; [NSThread detachNewThreadSelector:@selector(startTheBackgroundJob) toTarget:self withObject:nil]; } - (void)startTheBackgroundJob { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; currentLocationImageView = [[UIImageView alloc] init]; NSArray *images = [NSArray arrayWithObjects:img1, img2, nil]; [currentLocationImageView setAnimationImages:images]; [currentLocationImageView setAnimationRepeatCount:0]; [currentLocationImageView setAnimationDuration:5.0]; [self.view addSubview:currentLocationImageView]; [pool release]; }

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  • android thread management onPause

    - by Kwan Cheng
    I have a class that extends the Thread class and has its run method implemented as so. public void run(){ while(!terminate){ if(paused){ Thread.yield(); }else{ accummulator++; } } } This thread is spawned from the onCreate method. When my UI is hidden (when the Home key is pressed) my onPause method will set the paused flag to true and yield the tread. However in the DDMS I still see the uTime of the thread accumulate and its state as "running". So my question is. What is the proper way to stop the thread so that it does not use up CPU time?

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  • Thread Code...anything wrong with this, must use java 1.4

    - by bmw0128
    I have a servlet automatically firing up when the app server starts, and in its init(), I'm making another thread: init(){ new FooThread() } in FooThread(), i want to periodically check the status of a DB value, then depending on the value, make a web service call. When these two tasks complete, I want the thread to sleep to wait a certain period then repeat. This cycle would just continue forever. FooThread: public class FooThread implements Runnable{ Thread t; FooThread(){ t = new Thread(this, "BBSThread"); logger.info("*** about to start " + t.getName()); t.start(); logger.info("*** started: " + t); } public void run() { try{ while(true){ //do the db check, then conditionally do the web services call logger.info("*** calling sleep() ***"); Thread.sleep(50000); logger.info("*** now awake ***"); } } catch (InterruptedException e) { System.out.println("*** FooThread interrupted"); } } }

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  • When should ThreadLocal be used instead of Thread.SetData/Thread.GetData?

    - by Jon Ediger
    Prior to .net 4.0, I implemented a solution using named data slots in System.Threading.Thread. Now, in .net 4.0, there is the idea of ThreadLocal. How does ThreadLocal usage compare to named data slots? Does the ThreadLocal value get inherited by children threads? Is the idea that ThreadLocal is a simplified version of using named data slots? An example of some stuff using named data slots follows. Could this be simplified through use of ThreadLocal, and would it retain the same properties as the named data slots? public static void SetSliceName(string slice) { System.Threading.Thread.SetData(System.Threading.Thread.GetNamedDataSlot(SliceVariable), slice); } public static string GetSliceName(bool errorIfNotFound) { var slice = System.Threading.Thread.GetData(System.Threading.Thread.GetNamedDataSlot(SliceVariable)) as string; if (errorIfNotFound && string.IsNullOrEmpty(slice)) {throw new ConfigurationErrorsException("Server slice name not configured.");} return slice; }

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  • passing variables when calling methon in new thread (iphone)

    - by Mouhamad Lamaa
    dear stacks i need to pass variables to the thread method when creating a new thread my code is the follwing //generating thread [NSThread detachNewThreadSelector:@selector(startThread) toTarget:self withObject:nil]; thread job - (void)startThread:(NSInteger *)var img:(UIImageView *) Img{ NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; [NSThread sleepForTimeInterval:var]; [self performSelectorOnMainThread:@selector(threadMethod) withObject:nil waitUntilDone:NO]; //i need to pass Img to threadMethod: [pool release]; } thread Method - (void)threadMethod:(UIImageView *) Img { //do some coding. } so how i can do this (pass parameter to both of methods

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  • New form on a different thread

    - by Dan
    So I have a thread in my application, which purpose is to listen to messages from the server and act according to what it recieves. I ran into a problem when I wanted to fire off a message from the server, that when the client app recieves it, the client app would open up a new form. However this new form just freezes instantly. I think what's happening is that the new form is loaded up on the same thread as the thread listening to the server, which of course is busy listening on the stream, in turn blocking the thread. Normally, for my other functions in the clients listening thread, I'd use invokes to update the UI of the main form, so I guess what I'm asking for is if here's a way to invoke a new form on the main form.

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  • Setting minimum threads in thread pool

    - by expert
    I have an application with 4 worker threads from the thread pool. It was waking up every 0.5 second. as written in msdn the thread pool monitors every 0,5 second to create idle threads. I set the nuber of minimum threads to 4 and it solved the problem - no more background activity all the time. My question is - I have another applicatiopn which has the same number of threads threads-4, but here setting min thread to 4 doesn't help but when setting min thread to 5 then the background monitoring stops. What might be the difference between 2 application with the same number of threads from the thread pool- 4 threads.On one setting min threads to 4 helps and the other only setting min threads to 5 helps?

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  • Multi-threading does not work correctly using std::thread (C++ 11)

    - by user1364743
    I coded a small c++ program to try to understand how multi-threading works using std::thread. Here's the step of my program execution : Initialization of a 5x5 matrix of integers with a unique value '42' contained in the class 'Toto' (initialized in the main). I print the initialized 5x5 matrix. Declaration of std::vector of 5 threads. I attach all threads respectively with their task (threadTask method). Each thread will manipulate a std::vector<int> instance. I join all threads. I print the new state of my 5x5 matrix. Here's the output : 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 It should be : 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 0 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 Here's the code sample : #include <iostream> #include <vector> #include <thread> class Toto { public: /* ** Initialize a 5x5 matrix with the 42 value. */ void initData(void) { for (int y = 0; y < 5; y++) { std::vector<int> vec; for (int x = 0; x < 5; x++) { vec.push_back(42); } this->m_data.push_back(vec); } } /* ** Display the whole matrix. */ void printData(void) const { for (int y = 0; y < 5; y++) { for (int x = 0; x < 5; x++) { printf("%d ", this->m_data[y][x]); } printf("\n"); } printf("\n"); } /* ** Function attached to the thread (thread task). ** Replace the original '42' value by another one. */ void threadTask(std::vector<int> &list, int value) { for (int x = 0; x < 5; x++) { list[x] = value; } } /* ** Return the m_data instance propertie. */ std::vector<std::vector<int> > &getData(void) { return (this->m_data); } private: std::vector<std::vector<int> > m_data; }; int main(void) { Toto toto; toto.initData(); toto.printData(); //Display the original 5x5 matrix (first display). std::vector<std::thread> threadList(5); //Initialization of vector of 5 threads. for (int i = 0; i < 5; i++) { //Threads initializationss std::vector<int> vec = toto.getData()[i]; //Get each sub-vectors. threadList.at(i) = std::thread(&Toto::threadTask, toto, vec, i); //Each thread will be attached to a specific vector. } for (int j = 0; j < 5; j++) { threadList.at(j).join(); } toto.printData(); //Second display. getchar(); return (0); } However, in the method threadTask, if I print the variable list[x], the output is correct. I think I can't print the correct data in the main because the printData() call is in the main thread and the display in the threadTask function is correct because the method is executed in its own thread (not the main one). It's strange, it means that all threads created in a parent processes can't modified the data in this parent processes ? I think I forget something in my code. I'm really lost. Does anyone can help me, please ? Thank a lot in advance for your help.

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  • Core Data managed object context thread synchronisation

    - by Ben Reeves
    I'm have an issue where i'm updating a many-to-many relationship in a background thread, which works fine in that threa, but when I send the object back to the main thread the changes do not show. If I close the app and reopen the data is saved fine and the changes show on the main thread. Also using [context lock] instead of a different managed object context works fine. I have tried NSManagedObjectContext: - (BOOL)save:(NSError **)error; - (void)refreshObject:(NSManagedObject *)object mergeChanges:(BOOL)flag; at different stages throughout the process but it doesn't seem to help. My core data code uses the following getter to ensure any operations are thread safe: - (NSManagedObjectContext *) managedObjectContext { NSThread * thisThread = [NSThread currentThread]; if (thisThread == [NSThread mainThread]) { //Main thread just return default context return managedObjectContext; } else { //Thread safe trickery NSManagedObjectContext * threadManagedObjectContext = [[thisThread threadDictionary] objectForKey:CONTEXT_KEY]; if (threadManagedObjectContext == nil) { threadManagedObjectContext = [[[NSManagedObjectContext alloc] init] autorelease]; [threadManagedObjectContext setPersistentStoreCoordinator: [self persistentStoreCoordinator]]; [[thisThread threadDictionary] setObject:threadManagedObjectContext forKey:CONTEXT_KEY]; } return threadManagedObjectContext; } } and when I pass object between threads i'm using -(NSManagedObject*)makeSafe:(NSManagedObject*)object { if ([object managedObjectContext] != [self managedObjectContext]) { NSError * error = nil; object = [[self managedObjectContext] existingObjectWithID:[object objectID] error:&error]; if (error) { NSLog(@"Error makeSafe: %@", error); } } return object; } Any help appreciated

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  • WPF Background Thread Invocation

    - by jeffn825
    Maybe I'm mis-remembering how Winforms works or I'm overcomplicating the hell out of this, but here's my problem. I have a WPF client app application that talks to a server over WCF. The current user may "log out" of the WPF client, which closes all open screens, leaves only the navigation pane, and minimizes the program window. When the user re-maximizes the program window, they are prompted to log in. Simple. But sometimes things happen on background threads - like every 5 minutes the client tries to make a WCF calls that refreshes some cached data. And what if the user is logged out when this 5 minute timer triggers? Well, then the user should be prompted to log back in...and this must of course happen on the UI thread. private static ISecurityContext securityContext; public static ISecurityContext SecurityContext { get { if (securityContext == null) { // Login method shows a window and prompts the user to log in Application.Current.Dispatcher.Invoke((Action)Login); } return securityContext; } } So far so good, right? But what happens when multiple threads hit this spot of code? Well, my first intuition was that since I'm syncrhonizing across the Application.Current.Dispatcher, I should be fine, and whichever thread hit first would be responsible for showing the login form and getting the user logged in... Not the case... Thread 1 will hit the code and call ShowDialog on the login form Thread 2 will also hit the code and will call Login as soon as Thread 1 has called ShowDialog, since calling ShowDialog unblocked Thread 1 (I believe because of the way the WPF message pump works) All I want is a synchronized way of getting the user logged back into the application...what am I missing here? Thanks in advance.

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