Small demo to crash

crash.cpp

#include <QMap>
#include <QMapIterator>
#include <thread>
#include <QMutex>

QMap<int,QMap<QByteArray,QByteArray>> me;
QMap<QByteArray,QByteArray> row;
QMutex mutex;
void blaxx(){
	while(true){
		for (int i = 0; i < 200;) {
			mutex.lock();
			me.insert(i,row);
			mutex.unlock();
			i=i+5;
		}
	}
}

int main(){
	row.insert("srly","lol");

	std::thread th[1];
	th[0] = std::thread(blaxx);
mutex.lock();
	me.insert(10,row);
mutex.unlock();

	while(true){
		int k=4;
		QMap<int,QMap<QByteArray,QByteArray>>::iterator iter = me.begin();
		while(iter != me.end()){
			k = k + 5;
			QString dbname = iter.value().value("blablabla");
			mutex.lock();
			me.insert(k,row);
			iter = me.erase(iter);
			mutex.unlock();
		}
	}
}