QFileDialog在关闭/析构函数上冻结（带有选定文件或取消）

Question

I'm developing applications in qt with Ubuntu 15.04 and the respective qt pakage 5.4. For some reason, out of nowhere the application would freeze after selecting a file within a QFileDialog (or even cancelling).

I found some similar topics on the web but most were concerned with a now resolved bug in qt 5.1 and (non-)native QFileDialog s.

Then I found out this is related to more than just my own application - even qtcreator would freeze on leaving the QFileDialog , now.

There seems to be a deadlock in the destructor of QFileDialog .

Answer 1

The following snippet is from qsettings.cpp (line 1382), within void QConfFileSettingsPrivate::syncConfFile(int confFileNo)

QLockFile lockFile(confFile->name + QLatin1String(".lock"));
if (!readOnly) {
    if (!confFile->isWritable() || !lockFile.lock() ) {
        setStatus(QSettings::AccessError);
        return;
    }
}

It turns out some other qt application has left a lock file which causes all other applications' QFileDialog destructor to be deadlocked within the above lock call.

I searched for .lock files in my home folder and after deleting ./.config/QtProject.conf.lock and a second file similar to .config/USERNAME/APPTARGETNAME.conf.lock the QFileDialog works well, agian.

I just now can't reproduce which of the two files did cause the deadlock.

Hope this helps anyone in a similar situation!