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  • Python: nonblocking read from stdout of threaded subprocess

    - by sberry2A
    I have a script (worker.py) that prints unbuffered output in the form... 1 2 3 . . . n where n is some constant number of iterations a loop in this script will make. In another script (service_controller.py) I start a number of threads, each of which starts a subprocess using subprocess.Popen(stdout=subprocess.PIPE, ...); Now, in my main thread (service_controller.py) I want to read the output of each thread's worker.py subprocess and use it to calculate an estimate for the time remaining till completion. I have all of the logic working that reads the stdout from worker.py and determines the last printed number. The problem is that I can not figure out how to do this in a non-blocking way. If I read a constant bufsize then each read will end up waiting for the same data from each of the workers. I have tried numerous ways including using fcntl, select + os.read, etc. What is my best option here? I can post my source if needed, but I figured the explanation describes the problem well enough. Thanks for any help here. EDIT Adding sample code I have a worker that starts a subprocess. class WorkerThread(threading.Thread): def __init__(self): self.completed = 0 self.process = None self.lock = threading.RLock() threading.Thread.__init__(self) def run(self): cmd = ["/path/to/script", "arg1", "arg2"] self.process = subprocess.Popen(cmd, stdout=subprocess.PIPE, bufsize=1, shell=False) #flags = fcntl.fcntl(self.process.stdout, fcntl.F_GETFL) #fcntl.fcntl(self.process.stdout.fileno(), fcntl.F_SETFL, flags | os.O_NONBLOCK) def get_completed(self): self.lock.acquire(); fd = select.select([self.process.stdout.fileno()], [], [], 5)[0] if fd: self.data += os.read(fd, 1) try: self.completed = int(self.data.split("\n")[-2]) except IndexError: pass self.lock.release() return self.completed I then have a ThreadManager. class ThreadManager(): def __init__(self): self.pool = [] self.running = [] self.lock = threading.Lock() def clean_pool(self, pool): for worker in [x for x in pool is not x.isAlive()]: worker.join() pool.remove(worker) del worker return pool def run(self, concurrent=5): while len(self.running) + len(self.pool) > 0: self.clean_pool(self.running) n = min(max(concurrent - len(self.running), 0), len(self.pool)) if n > 0: for worker in self.pool[0:n]: worker.start() self.running.extend(self.pool[0:n]) del self.pool[0:n] time.sleep(.01) for worker in self.running + self.pool: worker.join() and some code to run it. threadManager = ThreadManager() for i in xrange(0, 5): threadManager.pool.append(WorkerThread()) threadManager.run() I have stripped out a log of the other code in hopes to try to pinpoint the issue.

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  • C# - periodic data reading and Thread.Sleep()

    - by CaldonCZE
    Hello, my C# application reads data from special USB device. The data are read as so-called "messages", each of them having 24 bytes. The amount of messages that must be read per second may differ (maximal frequency is quite high, about 700 messages per second), but the application must read them all. The only way to read the messages is by calling function "ReadMessage", that returns one message read from the device. The function is from external DLL and I cannot modify it. My solution: I've got a seperate thread, that is running all the time during the program run and it's only job is to read the messages in cycle. The received messages are then processed in main application thread. The function executed in the "reading thread" is the following: private void ReadingThreadFunction() { int cycleCount; try { while (this.keepReceivingMessages) { cycleCount++; TRxMsg receivedMessage; ReadMessage(devHandle, out receivedMessage); //...do something with the message... } } catch { //... catch exception if reading failed... } } This solution works fine and all messages are correctly received. However, the application consumes too much resources, the CPU of my computer runs at more than 80%. Therefore I'd like to reduce it. Thanks to the "cycleCount" variable I know that the "cycling speed" of the thread is about 40 000 cycles per second. This is unnecessarily too much, since I need to receive maximum 700 messagges/sec. (and the device has buffer for about 100 messages, so the cycle speed can be even a little lower) I tried to reduce the cycle speed by suspending the thread for 1 ms by Thread.Sleep(1); command. Of course, this didn't work and the cycle speed became about 70 cycles/second which was not enough to read all messages. I know that this attempt was silly, that putting the thread to sleep and then waking him up takes much longer than 1 ms. However, I don't know what else to do: Is there some other way how to slow the thread execution down (to reduce CPU consumption) other than Thread.Sleep? Or am I completely wrong and should I use something different for this task instead of Thread, maybe Threading.Timer or ThreadPool? Thanks a lot in advance for all suggestions. This is my first question here and I'm a beginner at using threads, so please excuse me if it's not clear enough.

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  • [C++] Producer/Consumer Implementation -- Feedback Wanted

    - by bobber205
    I'm preparing for an interview in a few weeks and I thougth I would give threads in boost a go, as well as do the simple producer/consumer problem I learned in school. Haven't done it quite awhile so I was curious what you guys think of this? What should I add to make it a better example etc. Thanks for the feedback! :) ////////////////////////////////////////////////////////////////////////// boost::mutex bufferMutex; deque<int> buffer; const int maxBufferSize = 5; ////////////////////////////////////////////////////////////////////////// bool AddToBuffer(int i) { if (buffer.size() < maxBufferSize) { buffer.push_back(i); return true; } else { return false; } } bool GetFromBuffer(int& toReturn) { if (buffer.size() == 0) { return false; } else { toReturn = buffer[buffer.size()-1]; buffer.pop_back(); return true; } } struct Producer { int ID; void operator()() { while (true) { boost::mutex::scoped_lock lock(bufferMutex); int num = dice(); bool result = AddToBuffer(num); lock.unlock(); //safe area done if (result) { cout << "Producer " << this->ID << " Added " << num << endl; } else { cout << "!!Buffer was Full!!" << endl; } //Added //Now wait boost::xtime xt; xtime_get( &xt, boost::TIME_UTC); xt.nsec += 1000000 + 100000 * (rand() % 1000); boost::thread::sleep(xt); } } }; struct Consumer { int ID; void operator()() { while (true) { int returnedInt = 0; boost::mutex::scoped_lock lock(bufferMutex); bool result = GetFromBuffer(returnedInt); lock.unlock(); //safe area done if (result) { cout << "\tConsumer " << this->ID << " Took Out " << returnedInt << endl; } else { cout << "!!Buffer was Empty!!" << endl; } //Added //Now wait boost::xtime xt; xtime_get( &xt, boost::TIME_UTC); xt.nsec += 1000000 + 100000 * (rand() % 1000); boost::thread::sleep(xt); } } }; void main() { Producer p, p2; Consumer c, c2; p.ID = 1; p2.ID = 2; c.ID = 1; c2.ID = 2; boost::thread thread1(boost::ref(p)); boost::thread thread2(boost::ref(c)); boost::thread thread3(boost::ref(p2)); boost::thread thread4(boost::ref(c2)); int x; cin >> x; }

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  • CPU Affinity Masks (Putting Threads on different CPUs)

    - by hahuang65
    I have 4 threads, and I am trying to set thread 1 to run on CPU 1, thread 2 on CPU 2, etc. However, when I run my code below, the affinity masks are returning the correct values, but when I do a sched_getcpu() on the threads, they all return that they are running on CPU 4. Anybody know what my problem here is? Thanks in advance! #define _GNU_SOURCE #include <stdio.h> #include <pthread.h> #include <stdlib.h> #include <sched.h> #include <errno.h> void *pthread_Message(char *message) { printf("%s is running on CPU %d\n", message, sched_getcpu()); } int main() { pthread_t thread1, thread2, thread3, thread4; pthread_t threadArray[4]; cpu_set_t cpu1, cpu2, cpu3, cpu4; char *thread1Msg = "Thread 1"; char *thread2Msg = "Thread 2"; char *thread3Msg = "Thread 3"; char *thread4Msg = "Thread 4"; int thread1Create, thread2Create, thread3Create, thread4Create, i, temp; CPU_ZERO(&cpu1); CPU_SET(1, &cpu1); temp = pthread_setaffinity_np(thread1, sizeof(cpu_set_t), &cpu1); printf("Set returned by pthread_getaffinity_np() contained:\n"); for (i = 0; i < CPU_SETSIZE; i++) if (CPU_ISSET(i, &cpu1)) printf("CPU1: CPU %d\n", i); CPU_ZERO(&cpu2); CPU_SET(2, &cpu2); temp = pthread_setaffinity_np(thread2, sizeof(cpu_set_t), &cpu2); for (i = 0; i < CPU_SETSIZE; i++) if (CPU_ISSET(i, &cpu2)) printf("CPU2: CPU %d\n", i); CPU_ZERO(&cpu3); CPU_SET(3, &cpu3); temp = pthread_setaffinity_np(thread3, sizeof(cpu_set_t), &cpu3); for (i = 0; i < CPU_SETSIZE; i++) if (CPU_ISSET(i, &cpu3)) printf("CPU3: CPU %d\n", i); CPU_ZERO(&cpu4); CPU_SET(4, &cpu4); temp = pthread_setaffinity_np(thread4, sizeof(cpu_set_t), &cpu4); for (i = 0; i < CPU_SETSIZE; i++) if (CPU_ISSET(i, &cpu4)) printf("CPU4: CPU %d\n", i); thread1Create = pthread_create(&thread1, NULL, (void *)pthread_Message, thread1Msg); thread2Create = pthread_create(&thread2, NULL, (void *)pthread_Message, thread2Msg); thread3Create = pthread_create(&thread3, NULL, (void *)pthread_Message, thread3Msg); thread4Create = pthread_create(&thread4, NULL, (void *)pthread_Message, thread4Msg); pthread_join(thread1, NULL); pthread_join(thread2, NULL); pthread_join(thread3, NULL); pthread_join(thread4, NULL); return 0; }

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  • Hibernate many-to-many mapping not saved in pivot table

    - by vincent
    I having problems saving many to many relationships to a pivot table. The way the pojos are created is unfortunately a pretty long process which spans over a couple of different threads which work on the (to this point un-saved) object until it is finally persisted. I associate the related objects to one another right after they are created and when debugging I can see the List of related object populated with their respective objects. So basically all is fine to this point. When I persist the object everything get saved except the relations in the pivot table. mapping files: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.thebeansgroup.jwinston.plugin.orm.hibernate.object"> <class name="ShowObject" table="show_object"> <id name="id"> <generator class="native" /> </id> <property name="name" /> <set cascade="all" inverse="true" name="venues" table="venue_show"> <key column="show_id"/> <many-to-many class="VenueObject"/> </set> </class> </hibernate-mapping> and the other <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.thebeansgroup.jwinston.plugin.orm.hibernate.object"> <class name="VenueObject" table="venue_object"> <id name="id"> <generator class="native"/> </id> <property name="name"/> <property name="latitude" type="integer"/> <property name="longitude" type="integer"/> <set cascade="all" inverse="true" name="shows" table="venue_show"> <key column="venue_id"/> <many-to-many class="ShowObject"/> </set> </class> </hibernate-mapping> pojos: public class ShowObject extends OrmObject { private Long id; private String name; private Set venues; public ShowObject() { } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Set getVenues() { return venues; } public void setVenues(Set venues) { this.venues = venues; } } and the other: public class VenueObject extends OrmObject { private Long id; private String name; private int latitude; private int longitude; private Set shows = new HashSet(); public VenueObject() { } @Id @GeneratedValue(strategy = GenerationType.AUTO) public Long getId() { return id; } public void setId(Long id) { this.id = id; } public int getLatitude() { return latitude; } public void setLatitude(int latitude) { this.latitude = latitude; } public int getLongitude() { return longitude; } public void setLongitude(int longitude) { this.longitude = longitude; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Set getShows() { return shows; } public void setShows(Set shows) { this.shows = shows; } } Might the problem be related to the lack of annotations?

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  • Async networking + threading problem

    - by randallmeadows
    I kick off a network request, assuming no login credentials are required to talk to the destination server. If they are required, then I get an authentication challenge, at which point I display a view requesting said credentials from the user. When they are supplied, I restart the network request, using those credentials. That's all fine and dandy, as long as I only do one request at a time. But I'm not, typically. When both requests are kicked off, I get the first challenge, and present the prompt (using -presentModalViewController:). Then the 2nd challenge comes in. And I crash when it tries to display the 2nd prompt. I have the bulk of this wrapped in an @synchronized() block, but this has no effect because these delegate methods are all being called on the same (main) thread. The docs say the delegate methods are called on the same thread in which the connection was started. OK, no problem; I'll just write a method that I run on a background thread using -performSelectorInBackground: NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO]; [connections addObject:connection]; [self performSelectorInBackground:@selector(startConnection:) withObject:connection]; [connection release]; - (void)startConnection:(NSURLConnection *)connection { NSAutoreleasePool *pool = [NSAutoreleasePool new]; [connection scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; [connection start]; [pool drain]; } which should put every network request, and its callbacks, on its own thread, and then my @synchronized() blocks will take effect. The docs for -initWithRequest:... state "Messages to the delegate will be sent on the thread that calls this method. By default, for the connection to work correctly the calling thread’s run loop must be operating in the default run loop mode." Ok, I'm doing that. They also state "If you pass NO [for startImmediately], you must schedule the connection in a run loop before starting it." OK, I'm doing that, too. Furthermore, the docs for NSRunLoop state "Each NSThread object, including the application’s main thread, has an NSRunLoop object automatically created for it as needed. If you need to access the current thread’s run loop, you do so with the class method currentRunLoop." I'm assuming this applies to the background thread created by the call -performSelectorInBackground... (which does appear to be the case, when I execute 'po [NSClassFromString(@"NSRunLoop") currentRunLoop]' in the -startConnection: method). The -startConnection: method is indeed being called. But after kicking off the connection, I now never get any callbacks on it. None of the -connectionDid… delegate methods. (I even tried explicitly starting the thread's run loop, but that made no difference; I've used threads like this before, and I've never had to start the run loop manually before--but I'm now grasping at straws...) I think I've come up with a workaround such that I only handle one request at a time, but it's kludgy and I'd like to do this the Right Way. But, what am I missing here? Thanks! randy

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  • Weird GWT issue causing IE threads to skyrocket.

    - by WesleyJohnson
    I'm not sure if this is an issue with GWT, JavaScript, Java, IE or just poor programming, but I'll try to explain. We're implementing web based chat program at work and some of our users have unreliable connections. So we're running into issues where they send out a new message and after x number of milliseconds have passed, the XHR request timesout and the client tries to resend the message again. The issue we ran into was sometimes the message would make it to the server and into the DB, but the XHR request wouldn't make it back to the client so the client was essentially retrying requests that had alread made it to the server. To mitigate this issue, we now send along a count/key with the message. The client says, hey I'm sending msg 50 and it's text is this. If the server already has that message, it just sends back "ok, I got it" and doens't insert into the DB again, eliminating dupes. So the client is free to keep retrying over and over until finally a call comes back from the server saying "Ok, I got it" and then it increments the key and moves on (or we keep them out of the chat if it fails enough). Anyway, so that's the background of what we're doing. The issue is, when we add this code on some versions of IE the threads start increasing gradually everytime it's accessed. On IE8 for Windows7 x64 it doesn't really seem to do it, but on IE8 for Windows Vista x86 it does. So I can't really pinpoint if it's a fluke or my code. Maybe someone had some ideas on a better way to do this. Here is some pseudo code: (the issue seems appear where I increment messageCount? Is this a scope thing, naming conflict, maybe the issue is entirely somewhere else and I'm way off base. public class SFChatClient implements EntryPoint { private List<String> messageQueue; private Integer messageCount = 0; public void onModuleLoad() { messageQueue = new ArrayList<String>(); // setup ui and what not // add a keyhandler to an input box that checks for <ENTER> and calls sendMEssage() } private void sendMessage() { // add message content to the UI for the chat messageQueue.add( //get message from user ); sendQueuedMessages(); } private void sendQueuedMessages() { if( messageQueue.size() > 0 ) { String outgoingMessage = messageQueue.get( 0 ); WebServiceClass.sendMessage( outgoingMessage, messageCount, new WebServiceHandler() { public void onSuccess() { // Delete item 0 from messageQueue messageCount = messageCount + 1; // <--- this seems to cause IE to leak threads. Taking out this code stops the issue??? sendQueuedMessages(); } public void onError() { // Do error handling sendQueuedMessages(); } } ); } } } public class WebServiceClass() { public void sendMessage( String message, Integer messageCount, handler ) { RequestBuilder builder = new RequestBuilder(// create request builder with proper params for the web service url, JSON content type, etc ) { public void onSuccess() { handler.onSuccess() } public void onError() { handler.onError() } } builder.setData( // JSON with message ); bulder.send(); } }

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  • Hibernate AssertionFailure in different Threads

    - by bladepit
    I connect to my database with one session. I have always the same session in my hole program. My Thread "1" catches primary data from the database. The user must be allowed to cancel this thread. So if the user presses the cancel button to often or to fast (this is my interpretation) the following error occures: ERROR org.hibernate.AssertionFailure - HHH000099: an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session) org.hibernate.AssertionFailure: possible non-threadsafe access to the session The same errors occures if i cancel my thread "2" which is running in the background after my thread "1" ist finished and the try to load another primary data set from the database. Is the failure that i am using the same session in my two threads? What is the right way to solve such a problem?

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  • Apache on linux : spawning processes or threads ?

    - by Jerome WAGNER
    Hello, I would like to understand better exactly what is going on when Apache on linux receive an HTTP request in a process pre-fork model. Let's say we have 20 Apache child processes waiting. When I receive an HTTP request, is it true to say that 1 child process will be chosen to handle the request and that this process won't handle another request from another user until the first one is finished ? I am asking the question because of a PHP limitation that states : The locale information is maintained per process, not per thread. If you are running PHP on a multithreaded server API like IIS or Apache on Windows, you may experience sudden changes in locale settings while a script is running, though the script itself never called setlocale(). This happens due to other scripts running in different threads of the same process at the same time, changing the process-wide locale using setlocale(). Thanks Jerome Wagner

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  • Scheduling Swingworker threads

    - by Simonw
    Hi, I have a 2 processes to perform in my swing application, one to fill a list, and one to do operations on each element on the list. I've just moved the 2 processes into Swingworker threads to stop the GUI locking up while the tasks are performed, and because I will need to do this set of operations to several lists, so concurrency wouldn't be a bad idea in the first place. However, when I just ran fillList.execute();doStuffToList.execute(); the doStuffToList thread to ran on the empty list (duh...). How do I tell the second process to wait until the first one is done? I suppose I could just nest the second process at the end of the first one, but i dunno, it seems like bad practice.

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  • Asynchronous Processing = Spanning Threads = Valid?

    - by jens
    Hello Experts, am I allowed (without any sideeffects) to create and start a new Thread() from within a doGet() Method of a servlet? Or does this somehow leak ressources? Is it valid to also pass the "Session" Object into the Thread to later save the result of my asynchronous processing (I will synchronized correctly) in the session? Or will this leak ressources when using the session "in indepedant threads"? = What would happen if the session meanwhile would be expired by the webcontainer as it has timedout and I will access it from my thread? Or would could this also lead to the sideffect, that storing the session in the thread will prevent the webcontainer from expiring the session at all (and therefore finally leak ressources as the sessions do not get cleared up)? (I know there are other Solutions, like working with DB-(Job)Records, JMS or Servlets 3.0) but I need so solve the problem as described by spanning a new Thread within doGet.) Thank you very much!! Jens

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  • Heuristic algorithm for load balancing among threads.

    - by Il-Bhima
    I'm working on a multithreaded program where I have a number of worker threads performing tasks of unequal length. I want to load-balance the tasks to ensure that they do roughly the same amount of work. For task T_i I have a number c_i which provides a good approximation to the amount of work that is required for that task. I'm looking for an efficient (O(N) N = num tasks or better) algorithm which will give me "roughly" a good load balance given the values of c_i. It doesn't have to be optimal, but I would like to be able to have some theoretical bounds on how bad the resulting allocations are. Any ideas?

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  • Please help. Creating threads and wait till finsh

    - by Raj Aththanayake
    Hi I have two method calls that I want to call using two threads. Then I want them to wait till method executions get completed before continuing. My sample solution is something like below. public static void Main() { Console.WriteLine("Main thread starting."); String[] strThreads = new String[] { "one", "two" }; String ctemp = string.Empty; foreach (String c in strThreads) { ctemp = c; Thread thread = new Thread(delegate() { MethodCall(ctemp); }); thread.Start(); thread.Join(); } Console.WriteLine("Main thread ending."); Console.Read(); } public static void MethodCalls(string number) { Console.WriteLine("Method call " + number); } Is this will do the job? Or is there another better way to do the same thing?

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  • Signals and threads - good or bad design decision?

    - by Jens
    I have to write a program that performs highly computationally intensive calculations. The program might run for several days. The calculation can be separated easily in different threads without the need of shared data. I want a GUI or a web service that informs me of the current status. My current design uses BOOST::signals2 and BOOST::thread. It compiles and so far works as expected. If a thread finished one iteration and new data is available it calls a signal which is connected to a slot in the GUI class. My question(s): Is this combination of signals and threads a wise idea? I another forum somebody advised someone else not to "go down this road". Are there potential deadly pitfalls nearby that I failed to see? Is my expectation realistic that it will be "easy" to use my GUI class to provide a web interface or a QT, a VTK or a whatever window? Is there a more clever alternative (like other boost libs) that I overlooked? following code compiles with g++ -Wall -o main -lboost_thread-mt <filename>.cpp code follows: #include <boost/signals2.hpp> #include <boost/thread.hpp> #include <boost/bind.hpp> #include <iostream> #include <iterator> #include <string> using std::cout; using std::cerr; using std::string; /** * Called when a CalcThread finished a new bunch of data. */ boost::signals2::signal<void(string)> signal_new_data; /** * The whole data will be stored here. */ class DataCollector { typedef boost::mutex::scoped_lock scoped_lock; boost::mutex mutex; public: /** * Called by CalcThreads call the to store their data. */ void push(const string &s, const string &caller_name) { scoped_lock lock(mutex); _data.push_back(s); signal_new_data(caller_name); } /** * Output everything collected so far to std::out. */ void out() { typedef std::vector<string>::const_iterator iter; for (iter i = _data.begin(); i != _data.end(); ++i) cout << " " << *i << "\n"; } private: std::vector<string> _data; }; /** * Several of those can calculate stuff. * No data sharing needed. */ struct CalcThread { CalcThread(string name, DataCollector &datcol) : _name(name), _datcol(datcol) { } /** * Expensive algorithms will be implemented here. * @param num_results how many data sets are to be calculated by this thread. */ void operator()(int num_results) { for (int i = 1; i <= num_results; ++i) { std::stringstream s; s << "["; if (i == num_results) s << "LAST "; s << "DATA " << i << " from thread " << _name << "]"; _datcol.push(s.str(), _name); } } private: string _name; DataCollector &_datcol; }; /** * Maybe some VTK or QT or both will be used someday. */ class GuiClass { public: GuiClass(DataCollector &datcol) : _datcol(datcol) { } /** * If the GUI wants to present or at least count the data collected so far. * @param caller_name is the name of the thread whose data is new. */ void slot_data_changed(string caller_name) const { cout << "GuiClass knows: new data from " << caller_name << std::endl; } private: DataCollector & _datcol; }; int main() { DataCollector datcol; GuiClass mc(datcol); signal_new_data.connect(boost::bind(&GuiClass::slot_data_changed, &mc, _1)); CalcThread r1("A", datcol), r2("B", datcol), r3("C", datcol), r4("D", datcol), r5("E", datcol); boost::thread t1(r1, 3); boost::thread t2(r2, 1); boost::thread t3(r3, 2); boost::thread t4(r4, 2); boost::thread t5(r5, 3); t1.join(); t2.join(); t3.join(); t4.join(); t5.join(); datcol.out(); cout << "\nDone" << std::endl; return 0; }

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  • Rendering to a single Bitmap object from multiple threads

    - by Lee Treveil
    What im doing is rendering a number of bitmaps to a single bitmap. There could be hundreds of images and the bitmap being rendered to could be over 1000x1000 pixels. Im hoping to speed up this process by using multiple threads but since the Bitmap object is not thread-safe it cant be rendered to directly concurrently. What im thinking is to split the large bitmap into sections per cpu, render them separately then join them back together at the end. I haven't done this yet incase you guys/girls have any better suggestions. Any ideas? Thanks

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  • Using a JMS Session from different threads

    - by Evan
    From the javadoc for Session it states: A Session object is a single-threaded context for producing and consuming messages. So I understand that you shouldn't use a Session object from two different threads at the same time. What I'm unclear on is if you could use the Session object (or children such as a Queue) from a different thread than the one it created. In the case I'm working on, I'm considering putting my Session objects into a pool of available sessions that any thread could borrow from, use, and return to the pool when it is finished with it. Is this kosher? (Using ActiveMQ BTW, if that impacts the answer at all.)

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  • Execuitng script in threads

    - by Pedro Magalhaes
    Hi. I wanna make an app that executes remote scripts. I am going to design it like a Windows Service that listen on tcp/ip port. Every new request I will execute a python scripts. So I can handle any number of tcp/ip request at same time, so I will need to execute python script in separate threads. How can I do that? Is that simple? The script will share some objects, like Log files(text files) and other modules. In the log file example every script will write in the same file. So the app (windows service) will be responsible for do that. I need to make this objects thread safe, right?

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  • Simple pygtk and threads example please.

    - by wtzolt
    Hello, Can someone give me a simple example involving threads in this manner, please. Problem with my code is that when I click button One, GUI freezes until its finished. I want buttons to stay responsive when def is being executed. How can i fix that? class fun: wTree = None def __init__( self ): self.wTree = gtk.glade.XML( "ui.glade" ) dic = { "on_buttonOne" : self.one, "on_buttonTwo" : self.two, } self.wTree.signal_autoconnect( dic ) gtk.main() def sone(self, widget): time.sleep(1) print "1" time.sleep(1) print "2" time.sleep(1) print "3" def stwo(self, widget): time.sleep(1) print "4" time.sleep(1) print "5" time.sleep(1) print "6" do=fun() Pretty please, help me.

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  • Maximizing the number of threads to fully utilize all available resources without hindering overall

    - by Matt
    Let's say I have to generate a bunch of result files, and I want to make it as fast as possible. Each result file is generated independently of any other result file; in fact, one could say that each result file is agnostic to every other result file. The resources used to generate each result file is also unique to each. How can I dynamically decide the optimal number of threads to run simultaneously in order to minimize the overall run time? Is my only option to write my own thread manager that watches performance counters and adjust accordingly or does there exists some solid classes that already accomplish this?

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  • asp.net Background Threads Exception Handling

    - by Chris
    In my 3.5 .net web application I have a background thread that does a lot of work (the application is similar to mint.com in that it does a lot of account aggregation on background threads). I do extensive exception handling within the thread performing the aggregation but there's always the chance an unhandled exception will be thrown and my entire application will die. I've read some articles about this topic but they all seem fairly outdated and none of them implement a standard approach. Is there a standard approach to this nowadays? Is there any nicer way to handle this in ASP.NET 4.0?

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  • Reading ResultSet from multiple threads

    - by superdario
    Hello, In the database, I have a definition table that is read from the application once upon starting. This definition table rarely changes, so it makes sense to read it once and restart the application every time it changes. However, after the table is read (put into a ResultSet), it will be read by multiple handlers running in their own threads. How do you suggest to accomplish this? My idea was to populate a CachedRowSet, and then create a copy of this set (through the createCopy() method) for each handler every time a new request comes. Do you think this is wise? Does this offer a good performance? Thanks.

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  • limit of connections with database and number of java threads in an application

    - by Jyoti
    Hi, I am working to develop a JMS application(stand alone multithreaded java application) which can receive 100 messages at a time , they need to be processed and database procedures need to be called for inserting/updating data. Procedures are very heavy as validations are also performed in them. Each procedure is taking about 30 to 50 seconds of time to execute and they are capable to run concurrently. My concern is to execute 100 procedures for all 100 messages and also send reply within time limit of 90 seconds by jms application. No application server to be used(requirement) and database is Teradata (RDBMS) I am using connection pool and thread pool in java code and testing code with 90 connections. Question is : (1) What should be the limit on number of connections with database at a time? (2) How many threads at a time are recommended? Thanks, Jyoti

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  • java.lang.OutOfMemoryError: unable to create new native thread for multiple threads

    - by Kaustubh Ranjan Singh
    static class solver implements Runnable { static calculator(problem){ //Some code if(condition) {solver s = new solver(newproblem); new Thread(s).start();} } Public solver(int newproblem) { this.problem = newproblem ; } public void run() { // TODO Auto-generated method stub calculator(promblem); } } i am having a big array maze of 100x100 and i am trying to solve it and i am getting an error java.lang.OutOfMemoryError: unable to create new native thread(after running a code for some times). How can solve this , How can i use ExecutorService i think that will solve the problem or i want something like thisIf Number of generated threads4K then stop the first 100 threads

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  • More threads and orientation changes questions.

    - by synic
    When it comes to threads and orientation changes, it seems the normal thing to do is something like this: public class Bwent extends Activity { private static Bwent instance; @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); instance = this; } //... That way, if you're making a network request with a thread, and someone changes the orientation of the phone, the thread will know to use the new Activity. However, is it possible that the thread could finish during the time Android is destroying the old Activity and creating a new one? Is there a moment in the process where the thread still might be pointing to the wrong Activity, or a partially destroyed activity? It seems like there shouldn't be, but even using a Handler created in the main thread, I'm having intermittent issues with a thread trying to update an object that no longer exists. It's rare, but it does happen.

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