multithreading

c# exception handling on background threads using Thread pool

Hi The application I am working on uses thread pool. Here's the basic pseudo code. On the main thread foreach(Object obj in Component.GetObject()) { //Invoke the thread pool providing the call back (method to be called on the background// thread) and pass the object as the parameter. } //Wait for the threads to complete. The "Com...

Win32 Event vs Semaphore

Basically I need a replacement for Condition Variable and SleepConditionVariableCS because it only support Vista and UP. (For C++) Some suggested to use Semaphore, I also found CreateEvent. Basically, I need to have on thread waiting on WaitForSingleObject, until something one or more others thread tell me there is something to do. In...

How to set WCF threads to schedual differently

Hi, I'm running a winservice that has 2 main objectives. Execute/Handle exposed webmethods. Run Inner processes that consume allot of CPU. The problem is that when I execute many inner processes |(as tasks) that are queued to the threadpool or taskpool, the execution of the webmethods takes much more time as WCF also queues its exec...

Why is my code stopping and not returning an exception?

I have some code that starts a couple of threads to let them execute, then uses a while loop to check for the current time passing a set timeout period, or for the correct number of results to have been processed (by checking an int on the class object) (with a Thread.Sleep() to wait between loops) Once the while loop is set to exit, it...

Buffering db inserts in multithreaded program

I have a system which breaks a large taks into small tasks using about 30 threads as a time. As each individual thread finishes it persists its calculated results to the database. What I want to achieve is to have each thread pass its results to a new persisance class that will perform a type of double buffering and data persistance whil...

passing parameters to a thread

I want to pass a function that takes a parameter to the ThreadStart Constructor in C#. But, it seems that this is not possible, as I get a syntax error it I try to do something like this Thread t1 = new Thread(new ThreadStart(func1(obj1)); where obj1 is an object of type List<string> (say). If I want a thread to execute this function...

Concurrent Threads in C# using BackgroundWorker

My C# application is such that a background worker is being used to wait for the acknowledgement of some transmitted data. Here is some psuedo code demonstrating what I'm trying to do: UI_thread { TransmitData() { // load data for tx // fire off TX background worker } RxSerialData() { // if received da...

Python MD5 Hash Faster Calculation

Hi everyone. I will try my best to explain my problem and my line of thought on how I think I can solve it. I use this code for root, dirs, files in os.walk(downloaddir): for infile in files: f = open(os.path.join(root,infile),'rb') filehash = hashlib.md5() while True: data = f.read(10240) if len(data) =...

Efficiently display file status when using background thread

How can i efficiently display the status of a file when using a background thread? For instance, lets say i have a 100MB file: when i do the code below via a thread (just as an example) it runs in about 1 min: foreach(byte b in file.bytes) { WriteByte(b, xxx); } But... if i want to update the user i have to use a delegate to upda...

how to know when a work in a thread is complete?

I need to create multiple threads when a button is clicked and i've done that with this: Dim myThread As New Threading.Thread(AddressOf getFile) myThread.IsBackground = True myThread.Start() but i need to update a picture box with the downloaded file, buy if i set an event in the function getFile and raise it to notify that the files ...

communication between threads in java

How can I make a thread run only if the other thread is running too, meaning, if I return from run in one thread, then I want the other to stop running too, my code looks something like this: ClientMessageHandler clientMessagehandler = new ClientMessageHandler(); ServerMessageHandler serverMessagehandler = new ServerMessageHandle...

What is the JVM Scheduling algorithm ?

Hello ! I am really curious about how does the JVM work with threads ! In my searches in internet, I found some material about RTSJ, but I don't know if it's the right directions for my answers. I also found this topic in sun's forums, http://forums.sun.com/thread.jspa?forumID=513&amp;threadID=472453, but that's not satisfatory. Can...

Why AutoResetEvent and ManualResetEvent does not support name in the constructor?

On .NET Framework 2.0 AutoResetEvent and ManualResetEvent inherit from EventWaitHandle. The EventWaitHandle class has 4 different constructors. 3 of the constructors support giving a name to the event. On the other hand both ManualResetEvent and AutoResetEvent do not support naming and provide a single constructor that receives the initi...

Lightweight alternative to Manual/AutoResetEvent in C#

Hi, I have written what I hope is a lightweight alternative to using the ManualResetEvent and AutoResetEvent classes in C#/.NET. The reasoning behind this was to have Event like functionality without the weight of using a kernel locking object. Although the code seems to work well in both testing and production, getting this kind of th...

C++ Mutexes and STL Lists Across Subclasses

I am currently writing a multi-threaded C++ server using Poco and am now at the point where I need to be keeping information on which users are connected, how many connections each of them have, and given it is a proxy server, where each of those connections are proxying through to. For this purpose I have created a ServerStats class wh...

Multithreaded SDL error in C++

I'm building a program in C++, using SDL, and am occasionally receiving this error: * glibc detected * ./assistant: double free or corruption (!prev) It's difficult to replicate, so I can't find exactly what's causing it, but I just added a second thread to the program, and neither thread run on its own seems to cause the error. The t...

Monotouch threads, GC, WCF

Hi This is a question about best practices i guess but it applies directly to my current MT project. I'm using WCF services to communicate with the server. To do this i do the following: services.MethodToCall(params); and the asynch: services.OnMethodToCallCompleted += delegate{ //do stuff and ting }; This can lead to issue...

Monitor.Wait, Pulse - When worker thread should conditionally behave as an actual worker thread

My particular scenario: - Main thread starts a worker thread. - Main thread needs to block itself until either worker thread is completed (yeah funny) or worker thread itself informs main thread to go on Alright, so what I did in main thread: wokerThread.Start(lockObj); lock(lockObj) Monitor.Wait(lockObj); Somewhere in worker thread...

Using Threading on Quad core speed up the code 65%?

This sample code compares serial method with threaded method, on Quad core processor. The code just uses GetPixel() to read all pixels from 4 images. I found that the speed up is around 65%, why it does not equal 75% as I have 4 cores and all of them are fully utilized? P.S: Can you check the code as I do not do any I/O, and no other p...

How do I call invokeLater or invokeAndWait in a BlackBerry / J2ME environment?

How do I call invokeLater or invokeAndWait in a BlackBerry / J2ME environment? I'm using RIM API 4.3. I know this is a basic question, but I can't find the method anywhere! Thanks, Dan ...