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  • How can I sync between multiple threads so that their transaction ID be unique without using mutex?

    - by poly
    I'm writing an application in C that requires multiple threads to request a unique transaction ID from a function as shown below; struct list{ int id; struct list *next }; function generate_id() { linked-list is built here to hold 10 millions } How can I sync between two or more threads so that their transaction ID be unique among them without using mutex, is it possible? Please share anything even if I need to change linked list to something else.

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  • running multi threads in Java

    - by owca
    My task is to simulate activity of couple of persons. Each of them has few activities to perform in some random time: fast (0-5s), medium(5-10s), slow(10-20s) and very slow(20-30s). Each person performs its task independently in the same time. At the beginning of new task I should print it's random time, start the task and then after time passes show next task's time and start it. I've written run() function that counts time, but now it looks like threads are done one after another and not in the same time or maybe they're just printed in this way. public class People{ public static void main(String[] args){ Task tasksA[]={new Task("washing","fast"), new Task("reading","slow"), new Task("shopping","medium")}; Task tasksM[]={new Task("sleeping zzzzzzzzzz","very slow"), new Task("learning","slow"), new Task(" :** ","slow"), new Task("passing an exam","slow") }; Task tasksJ[]={new Task("listening music","medium"), new Task("doing nothing","slow"), new Task("walking","medium") }; BusyPerson friends[]={ new BusyPerson("Alice",tasksA), new BusyPerson("Mark",tasksM), new BusyPerson("John",tasksJ)}; System.out.println("STARTING....................."); for(BusyPerson f: friends) (new Thread(f)).start(); System.out.println("DONE........................."); } } class Task { private String task; private int time; private Task[]tasks; public Task(String t, String s){ task = t; Speed speed = new Speed(); time = speed.getSpeed(s); } public Task(Task[]tab){ Task[]table=new Task[tab.length]; for(int i=0; i < tab.length; i++){ table[i] = tab[i]; } this.tasks = table; } } class Speed { private static String[]hows = {"fast","medium","slow","very slow"}; private static int[]maxs = {5000, 10000, 20000, 30000}; public Speed(){ } public static int getSpeed( String speedString){ String s = speedString; int up_limit=0; int down_limit=0; int time=0; //get limits of time for(int i=0; i<hows.length; i++){ if(s.equals(hows[i])){ up_limit = maxs[i]; if(i>0){ down_limit = maxs[i-1]; } else{ down_limit = 0; } } } //get random time within the limits Random rand = new Random(); time = rand.nextInt(up_limit) + down_limit; return time; } } class BusyPerson implements Runnable { private String name; private Task[] person_tasks; private BusyPerson[]persons; public BusyPerson(String s, Task[]t){ name = s; person_tasks = t; } public BusyPerson(BusyPerson[]tab){ BusyPerson[]table=new BusyPerson[tab.length]; for(int i=0; i < tab.length; i++){ table[i] = tab[i]; } this.persons = table; } public void run() { int time = 0; double t1=0; for(Task t: person_tasks){ t1 = (double)t.time/1000; System.out.println(name+" is... "+t.task+" "+t.speed+ " ("+t1+" sec)"); while (time == t.time) { try { Thread.sleep(10); } catch(InterruptedException exc) { System.out.println("End of thread."); return; } time = time + 100; } } } } And my output : STARTING..................... DONE......................... Mark is... sleeping zzzzzzzzzz very slow (36.715 sec) Mark is... learning slow (10.117 sec) Mark is... :** slow (29.543 sec) Mark is... passing an exam slow (23.429 sec) Alice is... washing fast (1.209 sec) Alice is... reading slow (23.21 sec) Alice is... shopping medium (11.237 sec) John is... listening music medium (8.263 sec) John is... doing nothing slow (13.576 sec) John is... walking medium (11.322 sec) Whilst it should be like this : STARTING..................... DONE......................... John is... listening music medium (7.05 sec) Alice is... washing fast (3.268 sec) Mark is... sleeping zzzzzzzzzz very slow (23.71 sec) Alice is... reading slow (15.516 sec) John is... doing nothing slow (13.692 sec) Alice is... shopping medium (8.371 sec) Mark is... learning slow (13.904 sec) John is... walking medium (5.172 sec) Mark is... :** slow (12.322 sec) Mark is... passing an exam very slow (27.1 sec)

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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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  • Should I build a multi-threaded system that handles events from a game and sorts them, independently, into different threads based on priority?

    - by JonathonG
    Can I build a multi-threaded system that handles events from a game and sorts them, independently, into different threads based on priority, and is it a good idea? Here's more info: I am about to begin work on porting a mid-sized game from Flash/AS3 to Java so that I can continue development with multi-threading capabilities. Here's a small bit of background about the game: The game contains numerous asynchronous activities, such as "world updating" (the game environment is constantly changing based on a set of natural laws and forces), procedural generation of terrain, NPCs, quests, items, etc., and on top of that, the effects of all of the player's interactions with his environment are programmatically calculated in real time, based on a set of constantly changing "stats" and once again, natural laws and forces. All of these things going on at once, in an asynchronous manner, seem to lend themselves to multi-threading very well. My question is: Can I build some kind of central engine that handles the "stacking" of all of these events as they are triggered, and dynamically sorts them out amongst the available threads, and would it be a good idea? As an example: Essentially, every time something happens (IE, a magic missile being generated by a spell, or a bunch of plants need to grow to their next stage), instead of just processing that task right then and adding the new object(s) to a list of managed objects, send a reference to that event to a core "event handler" that throws it into a stack of all other currently queued events, which then sorts them out and orders them according to urgency, splits them between a number of available threads for as-fast-as-possible multithreaded execution.

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  • ASIHTTP: multi threads and multi UIPorgressView

    - by user262325
    Hello everyone I have a project to download multi files (fileurl). It display the each thread on a UITableView. In UITableView - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSInteger row=[indexPath row]; NSInteger section=[indexPath section]; //UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:@"any-cell"]; static NSString *SimpleTableIdentifier1 = @"SimpleTableIdentifier1"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: SimpleTableIdentifier1]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier: SimpleTableIdentifier1] autorelease]; } UIProgressView *aUIProgressView; aUIProgressView =[[UIProgressView alloc] initWithFrame:CGRectMake( 10.9f,48.0f,300.0f,28.0f)]; [aUIProgressView setTag:row]; [aUIProgressView setProgress:0]; [cell addSubview:aUIProgressView]; [self startADownloadThread : [[downloadArray objectAtIndex:row] getURL] progressview:switchView ]; [aUIProgressView release]; [cell setText: [[downloadArray objectAtIndex:row] getURL]]; return cell; } It calls 'startADownloadThread' - (IBAction)startADownloadThread:(NSString *)fileurl progressview:(UIProgressView *)a { [a setProgress:0]; NSLog(@"Value: %f", [a progress]); [networkQueue cancelAllOperations]; [networkQueue setDownloadProgressDelegate:a]; [networkQueue setDelegate:self]; [networkQueue setRequestDidFinishSelector:@selector(requestDone:)]; [networkQueue setShowAccurateProgress:true]; NSURL *url = [NSURL URLWithString:fileurl]; ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url]; [request setDelegate:self]; [networkQueue addOperation:request]; [networkQueue go]; } I hope each aUIProgressView display the download progress of each download thread. The above source codes : Display the aUIProgressView list correctly, but only the last aUIProgressView link to a thread display the correct progress, others' value are 0 Welcome any comment Thanks interdev

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  • Updating Lucene index from two different threads in a web application

    - by Jimmy
    Hi, I've a .net web application which uses Lucene.net for company search functionality. When registered users add a new company,it is saved to database and also gets indexed in Lucene based company search index in real time. When adding company in Lucene index, how do I handle use case of two or more logged-in users posting a new company at the same time?Also, will both these companies get indexed without any file lock, lock time out, etc. related issues? Would appreciate if i could help with code as well. Thanks.

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  • C# Communication between threads.

    - by GT
    Hi, I am using .NET 3.5 and am trying to wrap my head around a problem (not being a supreme threading expert bear with me). I have a windows service which has a very intensive process that is always running, I have put this process onto a separate thread so that the main thread of my service can handle operational tasks - i.e., service audit cycles, handling configuration changes, etc, etc. I'm starting the thread via the typical ThreadStart to a method which kicks the process off - call it workerthread. On this workerthread I am sending data to another server, as is expected the server reboots every now and again and connection is lost and I need to re-establish the connection (I am notified by the lost of connection via an event). From here I do my reconnect logic and I am back in and running, however what I easily started to notice to happen was that I was creating this worker thread over and over again each time (not what I want). Now I could kill the workerthread when I lose the connection and start a new one but this seems like a waste of resources. What I really want to do, is marshal the call (i.e., my thread start method) back to the thread that is still in memory although not doing anything. Please post any examples or docs you have that would be of use. Thanks.

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  • Core Data passing context between methods on secondary threads

    - by JK
    My app spawns a secondary thread for some core data store maintenance. In the secondary thread, I set up a context which I then pass to other methods e.g. [self editEntriesInContext:context]. However, this causes objects fetched from the context to become invalidated in editEntries... Why does this occur? I thought the only requirements were for the secondary thread to have its own context and managed objects, which I adhere to. (Note: The context is properly retained)

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  • PyQt threads and signals - how to properly retrieve values

    - by Cawas
    Using Python 2.5 and PyQt, I couldn't find any question this specific in Python, so sorry if I'm repeating the other Qt referenced questions below, but I couldn't easily understand that C code. I've got two classes, a GUI and a thread, and I'm trying to get return values from the thread. I've used the link in here as base to write my code, which is working just fine. To sum it up and illustrate the question in code here (I don't think this code will run on itself): class MainWindow (QtGui.QWidget): # this is just a reference and not really relevant to the question def __init__ (self, parent = None): QtGui.QWidget.__init__(self, parent) self.thread = Worker() # this does not begin a thread - look at "Worker.run" for mor details self.connect(self.thread, QtCore.SIGNAL('finished()'), self.unfreezeUi) self.connect(self.thread, QtCore.SIGNAL('terminated()'), self.unfreezeUi) self.connect(self.buttonDaemon, QtCore.SIGNAL('clicked()'), self.pressDaemon) # the problem begins below: I'm not using signals, or queue, or whatever, while I believe I should def pressDaemon (self): self.buttonDaemon.setEnabled(False) if self.thread.isDaemonRunning(): self.thread.setDaemonStopSignal(True) self.buttonDaemon.setText('Daemon - converts every %s sec'% args['daemonInterval']) else: self.buttonConvert.setEnabled(False) self.thread.startDaemon() self.buttonDaemon.setText('Stop Daemon') self.buttonDaemon.setEnabled(True) # this whole class is just another reference class Worker (QtCore.QThread): daemonIsRunning = False daemonStopSignal = False daemonCurrentDelay = 0 def isDaemonRunning (self): return self.daemonIsRunning def setDaemonStopSignal (self, bool): self.daemonStopSignal = bool def __init__ (self, parent = None): QtCore.QThread.__init__(self, parent) self.exiting = False self.thread_to_run = None # which def will be running def __del__ (self): self.exiting = True self.thread_to_run = None self.wait() def run (self): if self.thread_to_run != None: self.thread_to_run(mode='continue') def startDaemon (self, mode = 'run'): if mode == 'run': self.thread_to_run = self.startDaemon # I'd love to be able to just pass this as an argument on start() below return self.start() # this will begin the thread # this is where the thread actually begins self.daemonIsRunning = True self.daemonStopSignal = False sleepStep = 0.1 # don't know how to interrupt while sleeping - so the less sleepStep, the faster StopSignal will work # begins the daemon in an "infinite" loop while self.daemonStopSignal == False and not self.exiting: # here, do any kind of daemon service delay = 0 while self.daemonStopSignal == False and not self.exiting and delay < args['daemonInterval']: time.sleep(sleepStep) # delay is actually set by while, but this holds for N second delay += sleepStep # daemon stopped, reseting everything self.daemonIsRunning = False self.emit(QtCore.SIGNAL('terminated')) Tho it's quite big, I hope this is pretty clear. The main point is on def pressDaemon. Specifically all 3 self.thread calls. The last one, self.thread.startDaemon() is just fine, and exactly as the example. I doubt that represents any issue. The problem is being able to set the Daemon Stop Signal and retrieve the value if it's running. I'm not sure that it's possible to set a stop signal on QtCore.QtThread, because I've tried doing the same way and it didn't work. But I'm pretty sure it's not possible to retrieve a return result from the emit. So, there it is. I'm using direct calls to the thread class, and I'm almost positive that's not a good design and will probably fail when running under stress. I read about that queue, but I'm not sure it's the proper solution here, or if I should be using Qt at all, since this is Python. And just maybe there's nothing wrong with the way I'm doing.

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  • How to set WCF threads to schedual differently

    - by Gilad
    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 executions to the same threadpool. This even happens when setting the inner processes task priority to lowest and setting the webmethods thread priority to heights. I hoped that Framework 4.0 would improve this, and they have, but still it takes quite allot of time for the system to handle the WCF queued tasks if the CPU is handling other inner tasks. Is it possible to change the Threadpool that WCF uses to a different one? Is it possible to manually change the task queue (global task queue, local task queue). Is it possible to manually handle 2 task queues that behave differently ? Any help in the subject would be appropriated. Gilad.

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  • Controllers and threads

    - by user72185
    Hi, I'm seeing this code in a project and I wonder if it is safe to do: (ASP.NET MVC 2.0) class MyController { void ActionResult SomeAction() { System.Threading.Thread newThread = new System.Threading.Thread(AsyncFunc); newThread.Start(); } void AsyncFunc() { string someString = HttpContext.Request.UrlReferrer.Authority + Url.Action("Index", new { controller = "AnotherAction" } ); } } Is the controller reused, possibly changing the content of HttpContext.Request and Url, or is this fine (except for not using the thread pool). Thanks for info!

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  • VirtualTreeView add roots with Threads

    - by Benjamin Weiss
    I would like to add roots to a VirtualTreeView http://www.delphi-gems.com/index.php/controls/virtual-treeview with a thread like this: function AddRoot ( p : TForm1 ) : Integer; stdcall; begin p.VirtualStringTree1.AddChild(NIL); end; var Dummy : DWORD; i : Integer; begin for i := 0 to 2000 do begin CloseHandle(CreateThread(NIL,0, @ADDROOT, Self,0, Dummy)); end; end; The reason for this is that I want to add all connections from my INDY Server to the TreeView. Indy's onexecute/onconnect get's called as a thread. So if 3+ connections come in at the same time the app crashes due to the TreeView. Same is if a client gets disconnected and I want to delete the Node. I am using Delphi7 and Indy9 Any Idea how to fix that?

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  • Identify cause of hundreds of AJP threads in Tomcat

    - by Rich
    We have two Tomcat 6.0.20 servers fronted by Apache, with communication between the two using AJP. Tomcat in turn consumes web services on a JBoss cluster. This morning, one of the Tomcat machines was using 100% of CPU on 6 of the 8 cores on our machine. We took a heap dump using JConsole, and then tried to connect JVisualVM to get a profile to see what was taking all the CPU, but this caused Tomcat to crash. At least we had the heap dump! I have loaded the heap dump into Eclipse MAT, where I have found that we have 565 instances of java.lang.Thread. Some of these, obviously, are entirely legitimate, but the vast majority are named "ajp-6009-XXX" where XXX is a number. I know my way around Eclipse MAT pretty well, but haven't been able to find an explanation for it. If anyone has some pointers as to why Tomcat may be doing this, or some hints on finding out why using Eclipse MAT, that'd be appreciated!

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  • Strange groovy behavior when dealing with threads

    - by Misha Koshelev
    Dear All: I have an interesting dilemma. If I define my class as: class Browser { def swtException protected Object evaluate(script) throws SWTException { swtException=null display.syncExec() { try { result=swtBrowser.evaluate(script) } catch (SWTException swtException) { Browser.swtException=swtException } } } I get this rather interesting error: Exception in thread "Thread-5" org.eclipse.swt.SWTException: Failed to execute runnable (groovy.lang.MissingPropertyException: No such property: swtException for class : com.mksoft.fbautomate.browser.Browser Possible solutions: swtException) Any ideas??? Thank you! Misha

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  • ASIHTTP: addOperation when other threads are running

    - by user262325
    Hello everyone I have a project using ASIHTTP to multi download files from a site when I add a new request: [networkQueue cancelAllOperations]; [networkQueue setDownloadProgressDelegate:a]; [networkQueue setDelegate:self]; [networkQueue setRequestDidFinishSelector:@selector(requestDone:)]; NSURL *url = [NSURL URLWithString:@"http://www.google.com"]; ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url]; [request setDelegate:self]; [request startAsynchronous]; [networkQueue addOperation:request]; [networkQueue go]; it reported: * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[ASINetworkQueue addOperation:]: operation is executing and cannot be enqueued' It looks like I can not add a new request when others are running. Welcome any comment Thanks interdev

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  • Android - Question on postDelayed and Threads

    - by Chris
    I have a question about postDelayed. The android docs say that it adds the runnable to the queue and it runs in the UI thread. What does this mean? So, for example, the same thread I use to create my layout is used to run the Runnable? What if I want it as an independent thread that executes while I am creating my layout and defining my activity? Thanks Chris

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  • Optimize code performance when odd/even threads are doing different things in CUDA

    - by Orion Nebula
    Hi all! I have two large vectors, I am trying to do some sort of element multiplication, where an even-numbered element in the first vector is multiplied by the next odd-numbered element in the second vector .... and where the odd-numbered element in the first vector is multiplied by the preceding even-numbered element in the second vector Ex. vector 1 is V1(1) V1(2) V1(3) V1(4) vector 2 is V2(1) V2(2) V2(3) V2(4) V1(1) * V2(2) V1(3) * V2(4) V1(2) * V2(1) V1(4) * V2(3) I have written a Cuda code to do this: (Pds has the elements of the first vector in shared memory, Nds the second Vector) //instead of using %2 .. i check for the first bit to decide if number is odd/even -- faster if ((tx & 0x0001) == 0x0000) Nds[tx+1] = Pds[tx] * Nds[tx+1]; else Nds[tx-1] = Pds[tx] * Nds[tx-1]; __syncthreads(); Is there anyway to further accelerate this code or avoid divergence ? Thanks

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  • create a list of threads in C

    - by Hristo
    My implementation (in C) isn't working... the first node is always NULL so I can't free the memory. I'm doing: thread_node_t *thread_list_head = NULL; // done in the beginning of the program ... // later on in the program thread_node_t *thread = (thread_node_t*) malloc(sizeof(thread_node_t)); pthread_create(&(thread->thread), NULL, client_thread, &csFD); thread->next = thread_list_head; thread_list_head = thread; So when I try to free this memory, thread_list_head is NULL. while (thread_list_head != NULL) { thread_node_t *temp = thread_list_head; thread_list_head = thread_list_head->next; free(temp); temp = NULL; } Any advice on how to fix this or just a new way to create this list that would work better? Thanks, Hristo

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  • CUDA threads output different value

    - by kar
    HAi, I wrote a cuda program , i have given the kernel function below. The device memory is allocated through CUDAMalloc(); the value of *md is 10; __global__ void add(int *md) { int x,oper=2; x=threadIdx.x; * md = *md*oper; if(x==1) { *md = *md*0; } if(x==2) { *md = *md*10; } if(x==3) { *md = *md+1; } if(x==4) { *md = *md-1; } } executed the above code add<<<1,5>>(*md) , add<<<1,4>>>(*md) for <<<1,5>>> the output is 19 for <<<1,4>>> the output is 21 1) I have doubt that cudaMalloc() will allocate in device main memory? 2) Why the last thread alone is executed always in the above program? Thank you

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  • Custom Classes Passed from Service to a UI threads via AIDL

    - by Honza Pokorny
    I have a service that regularly queries a web server for new messages. The service stores the new messages in an arrayList. These messages are implemented using a custom class, storing all kinds of metadata (strings and longs). An activity then connects to this service to retrieve those messages and display them to the user. I have an .aidl file that describes the interface that the service exposes. package com.example.package; interface MyInterface { List<Message> getMessages(); } The Message class extends the Parcelable class which should allow for the IPC transfer. The problem is this: Eclipse gives me an error saying that the type of List<Message> is unknown. Any imports are marked as invalid. Ideas? Thanks

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  • Optimize code perfromance when odd/even threads are doing different things in CUDA

    - by Ashraf
    Hi all! I have two large vectors, I am trying to do some sort of element multiplication, where an even-numbered element in the first vector is multiplied by the next odd-numbered element in the second vector .... and where the odd-numbered element in the first vector is multiplied by the preceding even-numbered element in the second vector Ex. vector 1 is V1(1) V1(2) V1(3) V1(4) vector 2 is V2(1) V2(2) V2(3) V2(4) V1(1) * V2(2) V1(3) * V2(4) V1(2) * V2(1) V1(4) * V2(3) I have written a Cuda code to do this: (Pds has the elements of the first vector in shared memory, Nds the second Vector) //instead of using %2 .. i check for the first bit to decide if number is odd/even -- faster if ((tx & 0x0001) == 0x0000) Nds[tx+1] = Pds[tx] * Nds[tx+1]; else Nds[tx-1] = Pds[tx] * Nds[tx-1]; __syncthreads(); Is there anyway to further accelerate this code or avoid divergence .. Thanks

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  • java and threads: very strange behaviour

    - by Derk
    private synchronized Map<Team, StandingRow> calculateStanding() { System.out.println("Calculate standing for group " + getName()); Map<Team, StandingRow> standing = new LinkedHashMap<Team, StandingRow>(); for (Team team : teams) { standing.put(team, new StandingRow(team)); } StandingRow homeTeamRow, awayTeamRow; for (Match match : matches.values()) { homeTeamRow = standing.get(match.getHomeTeam()); awayTeamRow = standing.get(match.getAwayTeam()); System.out.println("Contains key for " + match.getHomeTeam() + ": " + standing.containsKey(match.getHomeTeam())); System.out.println("Contains key for " + match.getAwayTeam() + ": " + standing.containsKey(match.getAwayTeam())); } } This is my code. matches contains 6 elements, but the problem is that after two matches no keys are anymore found in the standing map. The output is for example Contains key for Zuid-Afrika: true Contains key for Mexico: true Contains key for Uruguay: true Contains key for Frankrijk: true Contains key for Zuid-Afrika: false Contains key for Uruguay: false Contains key for Frankrijk: false Contains key for Mexico: false Contains key for Mexico: false Contains key for Uruguay: false Contains key for Frankrijk: false Contains key for Zuid-Afrika: false This is in a threaded environment, but the method is synchronized so I thought that this would not give a problem? I have also a simple unit test for this method and that works well.

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  • Cocoa multiple threads, locks don't work

    - by Igor
    I have a threadMethod which shows in console robotMotorsStatus every 0.5 sec. But when I try to change robotMotorsStatus in changeRobotStatus method I receive an exception. Where I need to put locks in that program. #import "AppController.h" @implementation AppController extern char *robotMotorsStatus; - (IBAction)runThread:(id)sender { [self performSelectorInBackground:@selector(threadMethod) withObject:nil]; } - (void)threadMethod { char string_to_send[]="QFF001100\r"; //String prepared to the port sending (first inintialization) string_to_send[7] = robotMotorsStatus[0]; string_to_send[8] = robotMotorsStatus[1]; while(1){ [theLock lock]; usleep(500000); NSLog (@"Robot status %s", robotMotorsStatus); [theLock unlock]; } } - (IBAction)changeRobotStatus:(id)sender { robotMotorsStatus[0]='1'; }

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