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  • Java: multi-threaded maps: how do the implementations compare?

    - by user346629
    I'm looking for a good hash map implementation. Specifically, one that's good for creating a large number of maps, most of them small. So memory is an issue. It should be thread-safe (though losing the odd put might be an OK compromise in return for better performance), and fast for both get and put. And I'd also like the moon on a stick, please, with a side-order of justice. The options I know are: HashMap. Disastrously un-thread safe. ConcurrentHashMap. My first choice, but this has a hefty memory footprint - about 2k per instance. Collections.sychronizedMap(HashMap). That's working OK for me, but I'm sure there must be faster alternatives. Trove or Colt - I think neither of these are thread-safe, but perhaps the code could be adapted to be thread safe. Any others? Any advice on what beats what when? Any really good new hash map algorithms that Java could use an implementation of? Thanks in advance for your input!

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  • How to share a dictionary between multiple processes in python without locking

    - by RandomVector
    I need to share a huge dictionary (around 1 gb in size) between multiple processs, however since all processes will always read from it. I dont need locking. Is there any way to share a dictionary without locking? The multiprocessing module in python provides an Array class which allows sharing without locking by setting lock=false however There is no such option for Dictionary provided by manager in multiprocessing module.

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  • Multithreaded update of multiple ProgressBars

    - by ClaudeS
    I have developped an application that can process data (in my case image algorithms performed on videos). I have developed different ProcessingMethods. Sometimes several videos are processed in parallel. Each process runs in a seperate thread. I have a GUI with several ProgressBars, one for each thread that is processing data. What is a good way to update the ProgressBar? Today my GUI is creating all the processing threads and one progressBars for each thread. Then I pass those progressBars to the threads, which pass them to the ProcessingMethod. The ProcessingMethod will then update the progressbar (using Invoke(..)). I have different processingMethods. Within each of these methods I have copy-paste code to update the progressBar. Although I am a new to programming, I know copy-paste is not good. What is a good way to make it better?

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  • How to check if a thread is busy in C#?

    - by Sam
    I have a Windows Forms UI running on a thread, Thread1. I have another thread, Thread2, that gets tons of data via external events that needs to update the Windows UI. (It actually updates multiple UI threads.) I have a third thread, Thread3, that I use as a buffer thread between Thread1 and Thread2 so that Thread2 can continue to update other threads (via the same method). My buffer thread, Thread3, looks like this: public class ThreadBuffer { public ThreadBuffer(frmUI form, CustomArgs e) { form.Invoke((MethodInvoker)delegate { form.UpdateUI(e); }); } } What I would like to do is for my ThreadBuffer to check whether my form is currently busy doing previous updates. If it is, I'd like for it to wait until it frees up and then invoke the UpdateUI(e). I was thinking about either: a) //PseudoCode while(form==busy) { // Do nothing; } form.Invoke((MethodInvoker)delegate { form.UpdateUI(e); }); How would I check the form==busy? Also, I am not sure that this is a good approach. b) Create an event in form1 that will notify the ThreadBuffer that it is ready to process. // psuedocode List<CustomArgs> elist = new List<CustomArgs>(); public ThreadBuffer(frmUI form, CustomArgs e) { from.OnFreedUp += from_OnFreedUp(); elist.Add(e); } private form_OnFreedUp() { if (elist.count == 0) return; form.Invoke((MethodInvoker)delegate { form.UpdateUI(elist[0]); }); elist.Remove(elist[0]); } In this case, how would I write an event that will notify that the form is free? and c) an other ideas?

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  • Objective-C: Allocation in one thread and release in other

    - by user423977
    Hi I am doing this in my Main Thread: CCAnimation *anim; //class variable [NSThread detachNewThreadSelector:@selector(loadAimation) toTarget:self withObject:nil]; In loadAimation: -(void) loadAimation { NSAutoreleasePool *autoreleasepool = [[NSAutoreleasePool alloc] init]; anim = [[CCAnimaton alloc] init]; [autoreleasepool drain]; } And in main thread I release it: [anim release]; Now I want to ask if this is fine regarding memory management.

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  • Implementing deadlock condition

    - by Bhaskar
    I am trying to implementing deadlock condition but somehow I am not able to get it working. Both the threads Thread1 and Thread2 are entering in the run function but only one of them enters in Sub/Sum depending on who entered run first. Example : if Thread2 entered run first the it will call sub() and Thread1 never calls sum(). I have also added sleep time so that Thread2 sleeps before calling sum() and Thread1 gets enough time to enter Sum() but Thread1 never enters. public class ExploringThreads { public static void main(String[] args) { // TODO Auto-generated method stub threadexample a1 = new threadexample(); Thread t1 = new Thread(a1, "Thread1"); Thread t2 = new Thread(a1,"Thread2"); t1.start(); t2.start(); } } class threadexample implements Runnable{ public int a = 10; public void run(){ if(Thread.currentThread().getName().equals("Thread1")) sum(); else if(Thread.currentThread().getName().equals("Thread2")) sub(); } public synchronized void sum() { try { Thread.sleep(2000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(Thread.currentThread().getName()+"In Sum"); sub(); } public synchronized void sub() { try { Thread.sleep(2000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(Thread.currentThread().getName()+"In Sub"); sum(); } }

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  • How to handle error on other thread?

    - by markattwood
    Hi, I'm trying to handle errors that have occurred on other threads the .NET CF program is like below: static void Main() { Thread t = new Thread(Start); t.Start(); ... } void Start() { ... Exception here } In my situation, putting try catch in the Start method is impossible. How can I handle it in the global code?

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  • Should I use multiple threads in this situation? [Ruby]

    - by mr popo
    I'm opening multiple files and processing them, one line at a time. The files contain tokens separating the data, such that sometimes the processing of one file may have to wait for others to catch up to that same token. I was doing this initially with only one thread and an array indicating with true/false if the file should be read in the current iteration or if it should wait for some of the others to catch up. Would using threads make this simpler? More efficient? Does Ruby have a mechanism for this?

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  • How to address thread-safety of service data used for maintaining static local variables in C++?

    - by sharptooth
    Consider the following scenario. We have a C++ function with a static local variable: void function() { static int variable = obtain(); //blahblablah } the function needs to be called from multiple threads concurrently, so we add a critical section to avoid concurrent access to the static local: void functionThreadSafe() { CriticalSectionLockClass lock( criticalSection ); static int variable = obtain(); //blahblablah } but will this be enough? I mean there's some magic that makes the variable being initialized no more than once. So there's some service data maintained by the runtime that indicates whether each static local has already been initialized. Will the critical section in the above code protect that service data as well? Is any extra protection required for this scenario?

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

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

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  • Corrupt output with an HttpModule

    - by clementi
    I have an HttpModule that looks at the query string for a parameter called "cmd" and executes one of a small set of predefined commands that display server stats in XML. For example, http://server01?cmd=globalstats. Now, on rare occasions, like once out of hundreds of times, I will get corrupt output like this: <!-- the stats start displaying fine... --> <stats> <ServerName>SERVER01</ServerName> <StackName>Search</StackName> <TotalRequests>945</TotalRequests> <!-- ...until something has gone awry and now we're getting the markup of the home page! --> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> ...the rest of the home page markup... (Remove the comments in the example above.) I'm not all that familiar with HttpModules and the IIS pipeline, but could this be a threading problem? Or, what else?

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  • Waiting for thread to finish Python

    - by lunchtime
    Alright, here's my problem. I have a thread that creates another thread in a pool, applies async so I can work with the returned data, which is working GREAT. But I need the current thread to WAIT until the result is returned. Here is the simplified code, as the current script is over 300 lines. I'm sure i've included everything for you to make sense of what I'm attempting: from multiprocessing.pool import ThreadPool import threading pool = ThreadPool(processes=1) class MyStreamer(TwythonStreamer): #[...] def on_success(self, data): #### Everytime data comes in, this is called #[...] #<Pseudocode> if score >= limit if list exists: Do stuff elif list does not exist: #</Pseudocode> dic = [] dic.append([k1, v1]) did = dict(dic) async_result = pool.apply_async(self.list_step, args=(did)) return_val = async_result.get() slug = return_val[0] idd = return_val[1] #[...] def list_step(self, *args): ## CREATE LIST ## RETURN 2 VALUES class threadStream (threading.Thread): def __init__(self, auth): threading.Thread.__init__(self) self.auth = auth def run(self): stream = MyStreamer(auth = auth[0], *auth[0]) stream.statuses.filter(track=auth[1]) t = threadStream(auth=AuthMe) t.start() I receive the results as intended, which is great, but how do I make it so this thread t waits for the async_result to come in?? My problem is everytime new data comes in, it seems that the ## CREATE LIST function is called multiple times if similar data comes in quickly enough. So I'm ending up with many lists of the same name when I have code in place to ensure that a list will never be created if the name already exists. So to reiterate: How do I make this thread wait on the function to complete before accepting new data / continuing. I don't think time.sleep() works because on_success is called when data enters the stream. I don't think Thread.Join() will work either since I have to use a ThreadPool.apply_async to receive the data I need. Is there a hack I can make in the MyStreamer class somehow? I'm kind of at a loss here. Am I over complicating things and can this be simplified to do what I want?

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

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

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  • Waiting for a submitted job to finish in Oracle PL/SQL?

    - by vicjugador
    I'm looking for the equivalent of Java's thread.join() in PL/SQL. I.e. I want to kick off a number of jobs (threads), and then wait for them to finish. How is this possible in PL/SQL? I'm thinking of using dbms_job.submit (I know it's deprecated). dbms_scheduler is also an alternative. My code: DECLARE jobno1 number; jobno2 number; BEGIN dbms_job.submit(jobno1,'begin dbms_lock.sleep(10); dbms_output.put_line(''job 1 exit'');end;'); dbms_job.submit(jobno2,'begin dbms_lock.sleep(10); dbms_output.put_line(''job 2 exit'');end;'); dbms_job.run(jobno1); dbms_job.run(jobno2); //Need code to Wait for jobno1 to finish //Need code to Wait for jobno2 to finish END;

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  • How to synchronize access to many objects

    - by vividos
    I have a thread pool with some threads (e.g. as many as number of cores) that work on many objects, say thousands of objects. Normally I would give each object a mutex to protect access to its internals, lock it when I'm doing work, then release it. When two threads would try to access the same object, one of the threads has to wait. Now I want to save some resources and be scalable, as there may be thousands of objects, and still only a hand full of threads. I'm thinking about a class design where the thread has some sort of mutex or lock object, and assigns the lock to the object when the object should be accessed. This would save resources, as I only have as much lock objects as I have threads. Now comes the programming part, where I want to transfer this design into code, but don't know quite where to start. I'm programming in C++ and want to use Boost classes where possible, but self written classes that handle these special requirements are ok. How would I implement this? My first idea was to have a boost::mutex object per thread, and each object has a boost::shared_ptr that initially is unset (or NULL). Now when I want to access the object, I lock it by creating a scoped_lock object and assign it to the shared_ptr. When the shared_ptr is already set, I wait on the present lock. This idea sounds like a heap full of race conditions, so I sort of abandoned it. Is there another way to accomplish this design? A completely different way?

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  • In C# is there a thread scheduler for long running threads?

    - by LogicMagic
    Hi, Our scenario is a network scanner. It connects to a set of hosts and scans them in parallel for a while using low priority background threads. I want to be able to schedule lots of work but only have any given say ten or whatever number of hosts scanned in parallel. Even if I create my own threads, the many callbacks and other asynchronous goodness uses the ThreadPool and I end up running out of resources. I should look at MonoTorrent... If I use THE ThreadPool, can I limit my application to some number that will leave enough for the rest of the application to Run smoothly? Is there a threadpool that I can initialize to n long lived threads?

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  • Threading in C#

    - by j-t-s
    Hi All Just looking for something ultra simple. I need to spawn a method off to a new thread. I don't care when or how it ends. Can somebody please help me with this? Thank you

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  • IS ResultSet thread safe

    - by javatraniee
    Is ResultSet Thread safe? My question arises because in this i have used a different statement for each query i have delsared a ResultSet as an local variable but it gives me a error of Operation not allowed after ResultSet is closed. But my statements are working as i'm using the statements in insert and delete query.I have commented the ResultSet part and have not got the error !! The source code of my program can be referd to , in my earlier Question .

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  • Threading across multiple files

    - by Zach M.
    My program is reading in files and using thread to compute the highest prime number, when I put a print statement into the getNum() function my numbers are printing out. However, it seems to just lag no matter how many threads I input. Each file has 1 million integers in it. Does anyone see something apparently wrong with my code? Basically the code is giving each thread 1000 integers to check before assigning a new thread. I am still a C noobie and am just learning the ropes of threading. My code is a mess right now because I have been switching things around constantly. #include <stdio.h> #include <stdlib.h> #include <time.h> #include <string.h> #include <pthread.h> #include <math.h> #include <semaphore.h> //Global variable declaration char *file1 = "primes1.txt"; char *file2 = "primes2.txt"; char *file3 = "primes3.txt"; char *file4 = "primes4.txt"; char *file5 = "primes5.txt"; char *file6 = "primes6.txt"; char *file7 = "primes7.txt"; char *file8 = "primes8.txt"; char *file9 = "primes9.txt"; char *file10 = "primes10.txt"; char **fn; //file name variable int numberOfThreads; int *highestPrime = NULL; int fileArrayNum = 0; int loop = 0; int currentFile = 0; sem_t semAccess; sem_t semAssign; int prime(int n)//check for prime number, return 1 for prime 0 for nonprime { int i; for(i = 2; i <= sqrt(n); i++) if(n % i == 0) return(0); return(1); } int getNum(FILE* file) { int number; char* tempS = malloc(20 *sizeof(char)); fgets(tempS, 20, file); tempS[strlen(tempS)-1] = '\0'; number = atoi(tempS); free(tempS);//free memory for later call return(number); } void* findPrimality(void *threadnum) //main thread function to find primes { int tNum = (int)threadnum; int checkNum; char *inUseFile = NULL; int x=1; FILE* file; while(currentFile < 10){ if(inUseFile == NULL){//inUseFIle being used to check if a file is still being read sem_wait(&semAccess);//critical section inUseFile = fn[currentFile]; sem_post(&semAssign); file = fopen(inUseFile, "r"); while(!feof(file)){ if(x % 1000 == 0 && tNum !=1){ //go for 1000 integers and then wait sem_wait(&semAssign); } checkNum = getNum(file); /* * * * * I think the issue is here * * * */ if(checkNum > highestPrime[tNum]){ if(prime(checkNum)){ highestPrime[tNum] = checkNum; } } x++; } fclose(file); inUseFile = NULL; } currentFile++; } } int main(int argc, char* argv[]) { if(argc != 2){ //checks for number of arguements being passed printf("To many ARGS\n"); return(-1); } else{//Sets thread cound to user input checking for correct number of threads numberOfThreads = atoi(argv[1]); if(numberOfThreads < 1 || numberOfThreads > 10){ printf("To many threads entered\n"); return(-1); } time_t preTime, postTime; //creating time variables int i; fn = malloc(10 * sizeof(char*)); //create file array and initialize fn[0] = file1; fn[1] = file2; fn[2] = file3; fn[3] = file4; fn[4] = file5; fn[5] = file6; fn[6] = file7; fn[7] = file8; fn[8] = file9; fn[9] = file10; sem_init(&semAccess, 0, 1); //initialize semaphores sem_init(&semAssign, 0, numberOfThreads); highestPrime = malloc(numberOfThreads * sizeof(int)); //create an array to store each threads highest number for(loop = 0; loop < numberOfThreads; loop++){//set initial values to 0 highestPrime[loop] = 0; } pthread_t calculationThread[numberOfThreads]; //thread to do the work preTime = time(NULL); //start the clock for(i = 0; i < numberOfThreads; i++){ pthread_create(&calculationThread[i], NULL, findPrimality, (void *)i); } for(i = 0; i < numberOfThreads; i++){ pthread_join(calculationThread[i], NULL); } for(i = 0; i < numberOfThreads; i++){ printf("this is a prime number: %d \n", highestPrime[i]); } postTime= time(NULL); printf("Wall time: %ld seconds\n", (long)(postTime - preTime)); } } Yes I am trying to find the highest number over all. So I have made some head way the last few hours, rescucturing the program as spudd said, currently I am getting a segmentation fault due to my use of structures, I am trying to save the largest individual primes in the struct while giving them the right indices. This is the revised code. So in short what the first thread is doing is creating all the threads and giving them access points to a very large integer array which they will go through and find prime numbers, I want to implement semaphores around the while loop so that while they are executing every 2000 lines or the end they update a global prime number. #include <stdio.h> #include <stdlib.h> #include <time.h> #include <string.h> #include <pthread.h> #include <math.h> #include <semaphore.h> //Global variable declaration char *file1 = "primes1.txt"; char *file2 = "primes2.txt"; char *file3 = "primes3.txt"; char *file4 = "primes4.txt"; char *file5 = "primes5.txt"; char *file6 = "primes6.txt"; char *file7 = "primes7.txt"; char *file8 = "primes8.txt"; char *file9 = "primes9.txt"; char *file10 = "primes10.txt"; int numberOfThreads; int entries[10000000]; int entryIndex = 0; int fileCount = 0; char** fileName; int largestPrimeNumber = 0; //Register functions int prime(int n); int getNum(FILE* file); void* findPrimality(void *threadNum); void* assign(void *num); typedef struct package{ int largestPrime; int startingIndex; int numberCount; }pack; //Beging main code block int main(int argc, char* argv[]) { if(argc != 2){ //checks for number of arguements being passed printf("To many threads!!\n"); return(-1); } else{ //Sets thread cound to user input checking for correct number of threads numberOfThreads = atoi(argv[1]); if(numberOfThreads < 1 || numberOfThreads > 10){ printf("To many threads entered\n"); return(-1); } int threadPointer[numberOfThreads]; //Pointer array to point to entries time_t preTime, postTime; //creating time variables int i; fileName = malloc(10 * sizeof(char*)); //create file array and initialize fileName[0] = file1; fileName[1] = file2; fileName[2] = file3; fileName[3] = file4; fileName[4] = file5; fileName[5] = file6; fileName[6] = file7; fileName[7] = file8; fileName[8] = file9; fileName[9] = file10; FILE* filereader; int currentNum; for(i = 0; i < 10; i++){ filereader = fopen(fileName[i], "r"); while(!feof(filereader)){ char* tempString = malloc(20 *sizeof(char)); fgets(tempString, 20, filereader); tempString[strlen(tempString)-1] = '\0'; entries[entryIndex] = atoi(tempString); entryIndex++; free(tempString); } } //sem_init(&semAccess, 0, 1); //initialize semaphores //sem_init(&semAssign, 0, numberOfThreads); time_t tPre, tPost; pthread_t coordinate; tPre = time(NULL); pthread_create(&coordinate, NULL, assign, (void**)numberOfThreads); pthread_join(coordinate, NULL); tPost = time(NULL); } } void* findPrime(void* pack_array) { pack* currentPack= pack_array; int lp = currentPack->largestPrime; int si = currentPack->startingIndex; int nc = currentPack->numberCount; int i; int j = 0; for(i = si; i < nc; i++){ while(j < 2000 || i == (nc-1)){ if(prime(entries[i])){ if(entries[i] > lp) lp = entries[i]; } j++; } } return (void*)currentPack; } void* assign(void* num) { int y = (int)num; int i; int count = 10000000/y; int finalCount = count + (10000000%y); int sIndex = 0; pack pack_array[(int)num]; pthread_t workers[numberOfThreads]; //thread to do the workers for(i = 0; i < y; i++){ if(i == (y-1)){ pack_array[i].largestPrime = 0; pack_array[i].startingIndex = sIndex; pack_array[i].numberCount = finalCount; } pack_array[i].largestPrime = 0; pack_array[i].startingIndex = sIndex; pack_array[i].numberCount = count; pthread_create(&workers[i], NULL, findPrime, (void *)&pack_array[i]); sIndex += count; } for(i = 0; i< y; i++) pthread_join(workers[i], NULL); } //Functions int prime(int n)//check for prime number, return 1 for prime 0 for nonprime { int i; for(i = 2; i <= sqrt(n); i++) if(n % i == 0) return(0); return(1); }

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  • How do I read and write to a file using threads in java?

    - by WarmWaffles
    I'm writing an application where I need to read blocks in from a single file, each block is roughly 512 bytes. I am also needing to write blocks simultaneously. One of the ideas I had was BlockReader implements Runnable and BlockWriter implements Runnable and BlockManager manages both the reader and writer. The problem that I am seeing with most examples that I have found was locking problems and potential deadlock situations. Any ideas how to implement this?

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  • Thread toggling

    - by sid
    Hi all, In Ubuntu, I am running 2 'C' applications, When I press key up/down the applications are alternatively getting the events. What might be the problem/solution? Ex: I have 'A application' and 'B application', I launch 'A application' and press the key up/down its working fine. If I simultaneously launch 'B application' and focus is on 'B application' then pressing key up/down will toggle between 'A application' & 'B application' so 2 times I have to press the key to move on 'B application'(focus is on 'B application'). 'A application' and 'B application' are threads. Thanks in advance-opensid

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  • Does SetThreadPriority cause thread reschedulling?

    - by Suma
    Consider following situation, assuming single CPU system: thread A is running with a priority THREAD_PRIORITY_NORMAL, signals event E thread B with a priority THREAD_PRIORITY_LOWEST is waiting for an event E (Note: at this point the thread is not scheduled because it is runnable, but A is higher priority and runnable as well) thread A calls SetThreadPriority(B, THREAD_PRIORITY_ABOVE_NORMAL) Is thread B re-scheduled immediately to run, or is thread A allowed to continue until current time-slice is over, and B is scheduled only once a new time-slice has begun? I would be interested to know the answer for WinXP, Vista and Win7, if possible. Note: the scenario above is simplified from my real world code, where multiple threads are running on multiple cores, but the main object of the question stays: does SetThreadPriority cause thread scheduling to happen?

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