Question

我有一个我正在进行并行化的n体仿真。我正在使用QT，所以我有一个自定义QObject类，它具有我已并行化的进程。它由一个刚处理线程的线程内的另一个QObject控制。问题是，每当一个对象与另一个对象发生碰撞时，必须停止所有线程，以便可以删除它们，并使用不同的行星系统重新创建。

这是线程处理程序类源：

#include "threadhandler.h"
#include <QEventLoop>
#include "subprocess.h"
#include <QThread>
#include <iostream>
#include <vector>
#include <thread>
#include <chrono>

ThreadHandler::ThreadHandler(double scopeX, double scopeY)
{
int size = 100;
int idealNum = QThread::idealThreadCount();
int sizeForEach = size/idealNum;

for(int i = 0 ; i< idealNum ;i++){
   SubProcess* tempSub = new SubProcess(i*sizeForEach, (i+1)*sizeForEach, scopeX, scopeY);
   QThread* tempThread = new QThread;
   tempSub->moveToThread(tempThread);
   QEventLoop::connect(tempSub, SIGNAL(finished()), tempThread, SLOT(deleteLater()));
   QEventLoop::connect(tempThread, SIGNAL(started()), tempSub, SLOT(process()));
   QEventLoop::connect(tempThread, SIGNAL(finished()), tempSub, SLOT(deleteLater()));
   QEventLoop::connect(tempSub, SIGNAL(collided()), this,
                       SLOT(refactorObjects()));
   ThreadHandler::threads.push_back(tempThread);
   ThreadHandler::objects.push_back(tempSub);
}
}

void ThreadHandler::process(){
std::cout << ThreadHandler::threads.size() << std::endl;
for(int i = 0; i < ThreadHandler::threads.size(); i++){
    std::cout << "starting " << i+1 << std::endl;
    ThreadHandler::threads.at(i)->start();
}
}

void ThreadHandler::refactorObjects(){
SubProcess::condition = false;
std::this_thread::sleep_for(std::chrono::seconds(1));
for(int i = 0 ; i < ThreadHandler::threads.size() ; i++){
    ThreadHandler::threads.at(i)->terminate();
}
ThreadHandler::objects.clear();
SubProcess::sys.push_back(Body::collide(SubProcess::collidedAr.at(0), SubProcess::collidedAr.at(1)));
SubProcess::sys.erase(std::remove(SubProcess::sys.begin(), SubProcess::sys.end(),
                                  SubProcess::collidedAr.at(0)), SubProcess::sys.end());
SubProcess::sys.erase(std::remove(SubProcess::sys.begin(), SubProcess::sys.end(),
                                  SubProcess::collidedAr.at(1)), SubProcess::sys.end());

int idealNum = QThread::idealThreadCount();
int sizeForEach = SubProcess::sys.size() / idealNum;
for(int i = 0 ; i < idealNum ; i++){
    SubProcess* tempSub = new SubProcess(i*sizeForEach, (i+1)*sizeForEach);
    tempSub->moveToThread(ThreadHandler::threads.at(i));
    ThreadHandler::objects.push_back(tempSub);
    QEventLoop::connect(tempSub, SIGNAL(finished()), ThreadHandler::threads.at(i), SLOT(deleteLater()));
    QEventLoop::connect(ThreadHandler::threads.at(i), SIGNAL(started()), tempSub, SLOT(process()));
    QEventLoop::connect(ThreadHandler::threads.at(i), SIGNAL(finished()), tempSub, SLOT(deleteLater()));
    QEventLoop::connect(tempSub, SIGNAL(collided()), this,
                        SLOT(refactorObjects()));
}

for(int i = 0; i < idealNum; i++){
    ThreadHandler::threads.at(i)->start();
}
std::cout << "refactored" << std::endl;
}

以下是子流程来源：

#include "subprocess.h"
#include <iostream>

std::vector<Body> SubProcess::sys;
std::vector<Body> SubProcess::collidedAr;
double SubProcess::timeScale;
bool SubProcess::condition = true;


SubProcess::SubProcess(double start, double end, double scopeX, double scopeY){
for(int i = start; i< end; i++){
    SubProcess::sys.push_back(Body::createRandomBody(scopeX, scopeY));
}
this->start = start;
this->end = end;
}
SubProcess::SubProcess(double start, double end){
this->start = start;
this->end = end;
}

void SubProcess::process(){
while(SubProcess::condition){
    for(int i = start; i < end ; i++){
        for(int j = 0; j < SubProcess::SubProcess::sys.size() ; j++){
            if(!(SubProcess::sys.at(i)==SubProcess::sys.at(j))){
                double F = Body::getForce(SubProcess::sys.at(i), SubProcess::sys.at(j));
                if (F!=-1){
                    double dX = SubProcess::sys.at(i).getX()-SubProcess::sys.at(j).getX();
                    double dY = SubProcess::sys.at(i).getY()-SubProcess::sys.at(j).getY();
                    SubProcess::sys.at(i).exertForce(-dY, -dX, F, timeScale);
                } else {
                    SubProcess::collidedAr.clear();
                    SubProcess::collidedAr.push_back(SubProcess::sys.at(i));
                    SubProcess::collidedAr.push_back(SubProcess::sys.at(j));
                    SubProcess::condition = false;
                    emit collided();
                }
            }
        }
        SubProcess::sys.at(i).tick(timeScale);
    }
}
emit finished();
}

每当我运行它时，它完全可以达到碰撞点：

starting 1
starting 2
starting 3
starting 4
refactored
refactored
QThread: Destroyed while thread is still running
QThread: Destroyed while thread is still running
QThread: Destroyed while thread is still running
QThread: Destroyed while thread is still running

所以对我来说没有意义的是，在重构过程开始时删除线程，并且不会产生错误。但由于某些原因，在新线程启动后，有些东西正在结束它们。我根本不知道这里发生了什么。我认为我不正确地处理和重新创建线程，并且应该有更好的方法。

Answer 1

一般来说，终止正在运行的线程会导致未定义的行为（与在其他数据一致的状态下被阻塞的线程相反）。你不应该终止线程。只需在子进程上执行deleteLater，它们就会自动处理它们。他们的线程不会受到影响。请参阅this answer，了解为什么可以在其他线程中的对象上调用deleteLater。

您应该保留一个线程池以供重用，无需重新创建它们。您甚至可以重复使用QThreadQueue。

默认QThread销毁非常不安全，如果可以的话，您应该使用a version without that deficiency。

不正确地终止线程？

1 个答案: