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  • Is there a chance that sending an email via a thread could ever fail to complete?

    - by Benjamin Dell
    I have a project where I send a couple of emails via a seperet thread, to speed up the process for the end-user. It works successfully, but i was just wondering whether there were any potfalls that i might not have considered? My greatest fear is that the user clicks a button, it says that the message has been sent (as it will have been sent to the thread for sending) but for some reason the thread might fail to send it. Are there any situations where a thread could be aborted prematurely? Please note, that i am not talking about network outages or obvious issues with an email recipient not existing. For simplicites sake please assume that the connect is up, the mail server alive and the recipient valid. Is it possible, for example, for the thread to abort prematurely if the user kills the browser before the thread has completed? This might be a silly question, but i just wanted to make sure i knew the full ramifications of using a thread in this manner. Thanks, in advance, for your help.

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  • Thread used for ServiceConnection callback (Android)

    - by Jannick
    Hi I'm developing an activity that binds to a local service (in onCreate of the activity): bindService(new Intent(this, CommandService.class), svcConn, BIND_AUTO_CREATE); I would like to be able to call methods through the IBinder in my lifecycle methods, but can not be sure that onServiceConnected have been called prior to these. I'm thinking of handling this by adding a queue of sorts in the ServiceConnection implementation, so that the method calls (Command pattern) will be executed once the connection is established. My questions are then: Is this stupid, any better ways? :) Are there any specification for which thread will be used to execute the ServiceConnection callbacks? More to the point, do I need to worry about synchronizing a queue datastructure? Edit - something like: public void onServiceConnected(ComponentName name, IBinder service) { dispatchService = (DispatchAsync)service; for(ExecutionTask task : queue){ dispatchService.execute(task.getCommand(), task); } }

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  • How to flush data in php and disconnect user but keep the script alive

    - by Rodrigo
    This is a trick question, while developing a php+ajax application i felt into some long queries, nothing wrong with them, but they could be done in background. I know that there's a way to just send a reply to user while throwing the real processing to another process by exec(), however it dosen't feels right for me, this might generate exploits and it's not pratical on making it compatible with virtual servers and cross platform. PHP offers the ob_* functions although they help on flushing the cache, but the user will keep connected until the script is running. I'm wondering if there's an alternate to exec to keep a script running after sending data to user and closing connection/thread with apache, or a less "dirty" way to have processing data sent to another script.

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  • Do breakpoints introduce delay?

    - by kamilo
    How is that setting a breakpoint in my code allows the following code to complete which would fail otherwise. Here is the problem. I'm writing an add-on for SAP B1 and encountered following problem. When I load a form I would like to enter some values into the form' matrix. But without a breakpoint (set on a method in which loading a form takes place) the part of code that is executed afterward will fail. That part of code is referencing a matrix that is not yet displayed which results in an exception. This is all clear. But why setting a breakpoint "solves" the problem. What is going on? I suspect that my breakpoint introduces some delay between loading and displaying my form and part of code that references element of that form but I could be wrong.

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  • How would you implement this "WorkerChain" functionality in .NET?

    - by Dan Tao
    Sorry for the vague question title -- not sure how to encapsulate what I'm asking below succinctly. (If someone with editing privileges can think of a more descriptive title, feel free to change it.) The behavior I need is this. I am envisioning a worker class that accepts a single delegate task in its constructor (for simplicity, I would make it immutable -- no more tasks can be added after instantiation). I'll call this task T. The class should have a simple method, something like GetToWork, that will exhibit this behavior: If the worker is not currently running T, then it will start doing so right now. If the worker is currently running T, then once it is finished, it will start T again immediately. GetToWork can be called any number of times while the worker is running T; the simple rule is that, during any execution of T, if GetToWork was called at least once, T will run again upon completion (and then if GetToWork is called while T is running that time, it will repeat itself again, etc.). Now, this is pretty straightforward with a boolean switch. But this class needs to be thread-safe, by which I mean, steps 1 and 2 above need to comprise atomic operations (at least I think they do). There is an added layer of complexity. I have need of a "worker chain" class that will consist of many of these workers linked together. As soon as the first worker completes, it essentially calls GetToWork on the worker after it; meanwhile, if its own GetToWork has been called, it restarts itself as well. Logically calling GetToWork on the chain is essentially the same as calling GetToWork on the first worker in the chain (I would fully intend that the chain's workers not be publicly accessible). One way to imagine how this hypothetical "worker chain" would behave is by comparing it to a team in a relay race. Suppose there are four runners, W1 through W4, and let the chain be called C. If I call C.StartWork(), what should happen is this: If W1 is at his starting point (i.e., doing nothing), he will start running towards W2. If W1 is already running towards W2 (i.e., executing his task), then once he reaches W2, he will signal to W2 to get started, immediately return to his starting point and, since StartWork has been called, start running towards W2 again. When W1 reaches W2's starting point, he'll immediately return to his own starting point. If W2 is just sitting around, he'll start running immediately towards W3. If W2 is already off running towards W3, then W2 will simply go again once he's reached W3 and returned to his starting point. The above is probably a little convoluted and written out poorly. But hopefully you get the basic idea. Obviously, these workers will be running on their own threads. Also, I guess it's possible this functionality already exists somewhere? If that's the case, definitely let me know!

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  • C# How to pause/suspend a thread then continue it?

    - by Russ K
    I am making an application in C# which uses a winform as the GUI and a separate thread which is running in the background automatically changing things. Ex: public void run() { while(true) { printMessageOnGui("Hey"); Thread.Sleep(2000); . . } } How would I make it pause anywhere in the loop, because one iteration of the loop takes around 30 seconds. So I wouldnt want to pause it after its done one loop, I want to pause it on time. Thanks!

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  • Identity.Name is disposed in a IIS7 Asp.NET MVC application Thread

    - by vIceBerg
    I have made the smallest demo project to illustrate my problem. You can download the sources Here Visual Studio 2008, .NET 3.5, IIS7, Windows 7 Ultimate 32 bits. The IIS Website is configured ONLY for Windows Authentication in an Integreated pipeline app pool (DefaultAppPool). Here's the problem. I have an Asp.NET MVC 2 application. In an action, I start a thread. The View returns. The thread is doing it's job... but it needs to access Thread.CurrentPrincipal.Identity.Name BANG The worker process of IIS7 stops. I have a window that says: "Visual Studio Just-In-Time Debugger An unhandled exception ('System.Object.DisposedException') occured in w3wp.exe [5524]" I checked with the debugger and the Thread.CurrentPrincipal.Identity is valid, but the Name property is disposed. If I put a long wait in the action before it returns the view, then the Thread can do it's job and the Identity.Name is not disposed. So I think the Name gets disposed when the view is returned. For the sake of the discussion, here's the code that the thread runs (but you can also download the demo project. The link is on top of this post): private void Run() { const int SECTOWAIT = 3; //wait SECTOWAIT seconds long end = DateTime.Now.Ticks + (TimeSpan.TicksPerSecond * SECTOWAIT); while (DateTime.Now.Ticks <= end) continue; //Check the currentprincipal. BANG!!!!!!!!!!!!! var userName = Thread.CurrentPrincipal.Identity.Name; } Here's the code that starts the thread public void Start() { Thread thread = new Thread(new ParameterizedThreadStart(ThreadProc)); thread.SetApartmentState(ApartmentState.MTA); thread.Name = "TestThread"; thread.Start(this); } static void ThreadProc(object o) { try { Builder builder = (Builder)o; builder.Run(); } catch (Exception ex) { throw; } } So... what am i doing wrong? Thanks

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  • Delegates And Cross Thread Exception

    - by Neo
    Whenever i am updating UI in windows form using delegate it gives me cross thread exception why it is happening like this? is there new thread started for each delegate call ? void Port_DataReceived(object sender, SerialDataReceivedEventArgs e) { //this call delegate to display data clsConnect(statusMsg); } protected void displayResponse(string resp) { //here cross thread exception occur if directly set to lblMsgResp.Text="Test"; if (lblMsgResp.InvokeRequired) { lblMsgResp.Invoke(new MethodInvoker(delegate { lblMsgResp.Text = resp; })); } }

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  • Tab Page launching a timer

    - by Lumpy
    I have a project that uses a timer to update the position of motors. I am adding 3 more motors and would like to control each of them the same way as the first. I tried moving my controls to a Tab Control but my update timers are not triggering. I made the UpdateTimer.SynchronizingObject = TheMainForm; Because if I tried to make it the Tab Page I got an error. I am very new to threaded projects. What am I doing wrong. Will post more code if its needed.

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  • custom progress bar in net compact framework

    - by amolitrivedi
    Hi all, I want to have my own progress bar in .net compact framework, instead of default wait cursor. I have tried with a form, having only a progress bar, and showing and hiding the form when I want to show some background activity running, but that does not update the progress bar. I have found out that it needs to be on different thread. I am quite weak at threads, I cant get it working. Please help me out. Thanks in advance.

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  • Self-updating collection concurrency issues

    - by DEHAAS
    I am trying to build a self-updating collection. Each item in the collection has a position (x,y). When the position is changed, an event is fired, and the collection will relocate the item. Internally the collection is using a “jagged dictionary”. The outer dictionary uses the x-coordinate a key, while the nested dictionary uses the y-coordinate a key. The nested dictionary then has a list of items as value. The collection also maintains a dictionary to store the items position as stored in the nested dictionaries – item to stored location lookup. I am having some trouble making the collection thread safe, which I really need. Source code for the collection: public class PositionCollection<TItem, TCoordinate> : ICollection<TItem> where TItem : IPositionable<TCoordinate> where TCoordinate : struct, IConvertible { private readonly object itemsLock = new object(); private readonly Dictionary<TCoordinate, Dictionary<TCoordinate, List<TItem>>> items; private readonly Dictionary<TItem, Vector<TCoordinate>> storedPositionLookup; public PositionCollection() { this.items = new Dictionary<TCoordinate, Dictionary<TCoordinate, List<TItem>>>(); this.storedPositionLookup = new Dictionary<TItem, Vector<TCoordinate>>(); } public void Add(TItem item) { if (item.Position == null) { throw new ArgumentException("Item must have a valid position."); } lock (this.itemsLock) { if (!this.items.ContainsKey(item.Position.X)) { this.items.Add(item.Position.X, new Dictionary<TCoordinate, List<TItem>>()); } Dictionary<TCoordinate, List<TItem>> xRow = this.items[item.Position.X]; if (!xRow.ContainsKey(item.Position.Y)) { xRow.Add(item.Position.Y, new List<TItem>()); } xRow[item.Position.Y].Add(item); if (this.storedPositionLookup.ContainsKey(item)) { this.storedPositionLookup[item] = new Vector<TCoordinate>(item.Position); } else { this.storedPositionLookup.Add(item, new Vector<TCoordinate>(item.Position)); // Store a copy of the original position } item.Position.PropertyChanged += (object sender, PropertyChangedEventArgs eventArgs) => this.UpdatePosition(item, eventArgs.PropertyName); } } private void UpdatePosition(TItem item, string propertyName) { lock (this.itemsLock) { Vector<TCoordinate> storedPosition = this.storedPositionLookup[item]; this.RemoveAt(storedPosition, item); this.storedPositionLookup.Remove(item); } } } I have written a simple unit test to check for concurrency issues: [TestMethod] public void TestThreadedPositionChange() { PositionCollection<Crate, int> collection = new PositionCollection<Crate, int>(); Crate crate = new Crate(new Vector<int>(5, 5)); collection.Add(crate); Parallel.For(0, 100, new Action<int>((i) => crate.Position.X += 1)); Crate same = collection[105, 5].First(); Assert.AreEqual(crate, same); } The actual stored position varies every time I run the test. I appreciate any feedback you may have.

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  • CreateThread() fails on 64 bit Windows, works on 32 bit Windows. Why?

    - by Stephen Kellett
    Operating System: Windows XP 64 bit, SP2. I have an unusual problem. I am porting some code from 32 bit to 64 bit. The 32 bit code works just fine. But when I call CreateThread() for the 64 bit version the call fails. I have three places where this fails. 2 call CreateThread(). 1 calls beginthreadex() which calls CreateThread(). All three calls fail with error code 0x3E6, "Invalid access to memory location". The problem is all the input parameters are correct. HANDLE h; DWORD threadID; h = CreateThread(0, // default security 0, // default stack size myThreadFunc, // valid function to call myParam, // my param 0, // no flags, start thread immediately &threadID); All three calls to CreateThread() are made from a DLL I've injected into the target program at the start of the program execution (this is before the program has got to the start of main()/WinMain()). If I call CreateThread() from the target program (same params) via say a menu, it works. Same parameters etc. Bizarre. If I pass NULL instead of &threadID, it still fails. If I pass NULL as myParam, it still fails. I'm not calling CreateThread from inside DllMain(), so that isn't the problem. I'm confused and searching on Google etc hasn't shown any relevant answers. If anyone has seen this before or has any ideas, please let me know. Thanks for reading.

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  • WCF MSMQ consumer thread count

    - by Andy White
    What's the best way to configure the maximum number of threads that can pull messages from an MSMQ queue, using a netMsmqBinding in WCF? For example, say I have an MSMQ service for which I only want to have 2 (or 10, or whatever number of) worker threads pulling messages off at a time.

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  • C#. How to terminate a thread which has spawned another thread which is sleeping?

    - by Bobb
    I have a long running thread made from Thread.Start(). It spawns a background thread using QueueUserWorkItem which sleeps most of the time. Then the class-owner get disposed I call thread1.Join() but naturally it doesnt return because its child background thread is sleeping. What would be the right solution to gracefully terminate a thread which has other threads with little hassle? Thanks

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  • Is PetraVM Jinx Beta 1 good?

    - by Brian T Hannan
    PetraVM recently came out with a Beta release of their Jinx product. Has anyone checked it out yet? Any feedback? By good, I mean: 1) easy to use 2) intuitive 3) useful 4) doesn't take a lot of code to integrate ... those kinds of things. Thanks guys!

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  • Do something else if ReadWriteSlimlock is held

    - by user43838
    Hi everyone, I have implemented ReaderWriterLockSlim, Now i don't want it to wait at the lock. I want to do something else if the lock is held. I considered using is isWriterLockHeld but it does not makes much sense to me, Since if two threads come in at the same time and enter the if statement at the same time one will still be waiting at the lock here is my code. ReaderWriterLockSlim rw = GetLoadingLock(parameters); rw = GetLoadingLock(parameters); try { rw.EnterWriteLock(); item = this.retrieveCacheItem(parameters.ToString(), false); if (item != null) { parameters.DataCameFromCache = true; // if the data was found in the cache, return it immediately return item.data; } else { try { object loaditem = null; itemsLoading[parameters.ToString()] = true; loaditem = this.retrieveDataFromStore(parameters); return loaditem; } finally { itemsLoading.Remove(parameters.ToString()); } } } finally { rw.ExitWriteLock(); } Can anyone please guide me in the right direction with this. Thanks

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  • How to terminate a thread which has spawned another thread which is sleeping?

    - by Bobb
    I have a long running thread made from Thread.Start(). It spawns a background thread using QueueUserWorkItem which sleeps most of the time. Then the class-owner get disposed I call thread1.Join() but naturally it doesnt return because its child background thread is sleeping. What would be the right solution to gracefully terminate a thread which has other threads with little hassle?

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  • Is there any point in using a volatile long?

    - by Adamski
    I occasionally use a volatile instance variable in cases where I have two threads reading from / writing to it and don't want the overhead (or potential deadlock risk) of taking out a lock; for example a timer thread periodically updating an int ID that is exposed as a getter on some class: public class MyClass { private volatile int id; public MyClass() { ScheduledExecutorService execService = Executors.newScheduledThreadPool(1); execService.scheduleAtFixedRate(new Runnable() { public void run() { ++id; } }, 0L, 30L, TimeUnit.SECONDS); } public int getId() { return id; } } My question: Given that the JLS only guarantees that 32-bit reads will be atomic is there any point in ever using a volatile long? (i.e. 64-bit). Caveat: Please do not reply saying that using volatile over synchronized is a case of pre-optimisation; I am well aware of how / when to use synchronized but there are cases where volatile is preferable. For example, when defining a Spring bean for use in a single-threaded application I tend to favour volatile instance variables, as there is no guarantee that the Spring context will initialise each bean's properties in the main thread.

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