[Qt-interest] How to stop threads started by QFileSystemModel (QFileInfoGatherer, QWindowsFileSystemWatcherEngine)?

[Thiago Macieira]

Em Quinta-feira 20 Agosto 2009, às 13:10:02, Niels Dekker - no return address 
escreveu:
> Our code basically does:
> 
>   QFileSystemModel* fileSystemModel = new QFileSystemModel();
>   treeView->setModel(fileSystemModel);
> 
> Within the constructor of QFileSystemModel, a thread is created
> ('QFileInfoGatherer'). During the lifetime of fileSystemModel, some
> other threads are created, including 'QWindowsFileSystemWatcherEngine'.
> Unfortunately the destructor of QFileSystemModel doesn't delete those
> threads. Is that a bug?

Yes.

The destructor does delete the thread:

QFileInfoGatherer::~QFileInfoGatherer()
{
    mutex.lock();
    abort = true;
    condition.wakeOne();
    mutex.unlock();
    wait();
}

However, the "abort" variable is not declared volatile. The thread may never 
notice that the variable changed asynchronously, so the optimiser may remove 
the check altogether.

But if that happened, then wait() would block forever (well, for 49.7 days). 
You'd have noticed that.

So my conclusion is that the thread is stopped.

> Anyway, it appears that those threads cause a crash of our application,
> because they keep running, even when qApp is destructed and Qt's DLL's
> are unloaded. Is there a way to stop the threads created by
> QFileSystemModel?

The code tries to stop them

-- 
Thiago Macieira - thiago.macieira (AT) nokia.com
  Senior Product Manager - Nokia, Qt Development Frameworks
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