Fw: Use of QMutex not as expected
The problem appears to be that each of your threads is locking a
different mutex, and so there is no synchronization among them.
Probably you want your worker classes to store myResource by reference
rather than by value (and eliminate the copy-constructor of
myResource, and better yet make it non-copyable). That way there will
be only one myResource object, and only one mutex.
-Gabe
On Tue, Aug 25, 2015 at 7:31 AM, Don El Ron
Dear all,
I use the following code:
__________________________________________________________________ #include
#include class myRessource{ public: myRessource() : m_iValue(0){} //copy ctor necessary, so a member of type boost::mutex is possible in this class myRessource(const myRessource ©Res) : m_iValue(0){} ~myRessource(){} void SendCommand(int ival){ myMutex.lock(); m_iValue=ival; std::cout << "resource update to " << ival << " active count is " << myMutex.active_count << std::endl; myMutex.unlock(); } private: int m_iValue; boost::mutex myMutex; };
int iSleepTime1=200; int iSleepTime2=30;
class myWorker1 { public: myWorker1(myRessource res): m_res(res){} ~myWorker1(){} void DoWork(void){ m_res.SendCommand(1); boost::this_thread::sleep(boost::posix_time::milliseconds(iSleepTime1)); m_res.SendCommand(2); boost::this_thread::sleep(boost::posix_time::milliseconds(iSleepTime1)); m_res.SendCommand(3); boost::this_thread::sleep(boost::posix_time::milliseconds(iSleepTime1)); m_res.SendCommand(4); boost::this_thread::sleep(boost::posix_time::milliseconds(iSleepTime1)); } private: myRessource m_res; };
class myWorker2 { public: myWorker2(myRessource res): m_res(res){} ~myWorker2(){} void DoWork(void){ m_res.SendCommand(201); boost::this_thread::sleep(boost::posix_time::milliseconds(iSleepTime2)); m_res.SendCommand(202); boost::this_thread::sleep(boost::posix_time::milliseconds(iSleepTime2)); m_res.SendCommand(203); boost::this_thread::sleep(boost::posix_time::milliseconds(iSleepTime2)); m_res.SendCommand(204); boost::this_thread::sleep(boost::posix_time::milliseconds(iSleepTime2)); } private: myRessource m_res; };
int main(int argc, char *argv[]) { myRessource r; myWorker1 w1(r); boost::thread workerThread1(&myWorker1::DoWork, &w1);
myWorker2 w2(r); boost::thread workerThread2(&myWorker2::DoWork, &w2); workerThread1.join(); workerThread2.join(); } ___ _______________________________________________________________ This results in the following output (no formatting, e.g. line breaks done):
resource update to resource update to 201 active count is -21474836481 active co unt is -2147483648 resource update to 202 active count is -2147483648 resource update to 203 active count is -2147483648 resource update to 204 active count is -2147483648 resource update to 2 active count is -2147483648 resource update to 3 active count is -2147483648 resource update to 4 active count is -2147483648
The output always looks like this, i. e. the first two lines are "merged", whereas the remaining lines look just fine. Why does this happen and what do I have to do in order to correct my mistake??? Many thanks in advance!
_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
Il 25/08/2015 13:31, Don El Ron ha scritto: It seems that each myResource instannstance has its own mutex, so if you pass it by copy in the MyWorkerXX constructors each of the MyWorkerXX instance will lock on a different mutex. This can be avoided in many ways, it depends on what kind of locking is required: 1) if each MyResource still needs a separate mutex, then you should pass it to MyWorkerXX class by reference, so each worker thread will lock on the same mutex 2) if all of MyResouce instances must be synchronized on the same mutex, then you can make the mutex object static and pass MyResouce to MyWorkerXX as you like, as the mutex will always be the same regards Lorenzo
participants (3)
-
Don El Ron -
Gabriel Redner -
Lorenzo Trivelli