QtConcurrent::map cause crash

TonyTang

dear all:
when I call QtConcurrent::map,the program crashs down sometimes. I do not know why.thanks for your suggestion! my code as following :

void MutiFun(int& i)
{
	i *= 2;
}
const int nSize = 10000000;
QList<int> dataArray1;
for (int i = 0; i < nSize; i++)
{
	dataArray1.push_back(i);
}
QFuture<void> f = QtConcurrent::map(dataArray1, MutiFun);
f.waitForFinished();

JonB

@TonyTang
What does the debugger reveal in the stack trace pane when it "crashs down sometimes"?

TonyTang

@JonB

Qt5Cored.dll!QGenericAtomicOps<QAtomicOpsBySize<4> >::store<int,int>(int & _q_value, int newValue) 行 89 C++
Qt5Cored.dll!QBasicAtomicInteger<int>::store(int newValue) 行 120 C++
Qt5Cored.dll!QFreeList<QMutexPrivate,`anonymous namespace'::FreeListConstants>::release(int id) 行 270 C++
Qt5Cored.dll!QMutexPrivate::release() 行 601 C++
Qt5Cored.dll!QMutexPrivate::deref() 行 106 C++
Qt5Cored.dll!QBasicMutex::lockInternal(int timeout) 行 496 C++
Qt5Cored.dll!QBasicMutex::lockInternal() 行 416 C++
Qt5Cored.dll!QMutex::lock() 行 225 C++
Qt5Cored.dll!QMutexLocker::relock() 行 147 C++
Qt5Cored.dll!QThreadPoolThread::run() 行 105 C++
Qt5Cored.dll!QThreadPrivate::start(void * arg) 行 387 C++
ucrtbased.dll!00007ff828c8a1bc() 未知
ucrtbased.dll!00007ff828c89e13() 未知
kernel32.dll!00007ff8667a37e4() 未知
ntdll.dll!00007ff86713cb81() 未知

Christian Ehrlicher

Your code works fine here.

TonyTang

@Christian-Ehrlicher
sometimes it works fine,but sometimes not
It may be the problem of multithreading synchronization

Christian Ehrlicher

@TonyTang I doubt there is a problem in the Qt implementation of QtConcurrent::map() so I would guess your code does more than you've shown above. The code above runs fine standalone, with valgrind, with address sanitizer and thread sanitizer (at least no real problems seen here). Also let your program run 10k times without any crash.

TonyTang

@Christian-Ehrlicher
The whole code as following

#include <QtCore/QCoreApplication>
#include <QtConcurrent/QtConcurrent>
#include <QList>
#include <QDebug>
#include <QThread>
#include <QTime>
void MutiFun(int& i)
{
i *= 2;
}

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);

const int nSize = 10000000;
QList<int> dataArray1;
for (int i = 0; i < nSize; i++)
{
	dataArray1.push_back(i);
}
QFuture<void> f = QtConcurrent::map(dataArray1, MutiFun);
f.waitForFinished();

return a.exec();

}

and stack trace is here
ntdll.dll!00007ff8671d4c2e() 未知
ntdll.dll!00007ff86718d063() 未知
ntdll.dll!00007ff86711bf55() 未知
KernelBase.dll!00007ff863ae136a() 未知
ucrtbased.dll!00007ff828b3deb1() 未知
ucrtbased.dll!00007ff828b3d350() 未知
ucrtbased.dll!00007ff828b3faf9() 未知
ucrtbased.dll!00007ff828b4075e() 未知
Qt5Cored.dll!QListData::realloc_grow(int growth) 行 156 C++
Qt5Cored.dll!QListData::append(int n) 行 185 C++
Qt5Cored.dll!QListData::append() 行 193 C++

Qt5Cored.dll!QList<QThreadPoolThread * __ptr64>::append(QThreadPoolThread * const & t) 行 592 C++
Qt5Cored.dll!QQueue<QThreadPoolThread * __ptr64>::enqueue(QThreadPoolThread * const & t) 行 53 C++
Qt5Cored.dll!QThreadPoolThread::run() 行 125 C++
Qt5Cored.dll!QThreadPrivate::start(void * arg) 行 387 C++
ucrtbased.dll!00007ff828b6a1bc() 未知
ucrtbased.dll!00007ff828b69e13() 未知
kernel32.dll!00007ff8667a37e4() 未知
ntdll.dll!00007ff86713cb81() 未知

Christian Ehrlicher

I can't reproduce it with gcc7 or 10 on linux or msvc2019 16.8.3 / 64bit with Qt5.15.