When QSqlDatabase::removeDatabase() is called from a different thread than QSqlDatabase::addDatabase() was called from, I get the following error message:
Error in my_thread_global_end(): 1 threads didn't exit
It is easy to reproduce with the following code sample even without MySql database. But it seems to happen on Ubuntu and NOT on Windows.

Qt Code: 
  1. #include <QtCore>
  2. #include <QtSql>
  3.  
  4. class Client: public QObject
  5. {
  6.     Q_OBJECT
  7.  
  8. public:
  9.     Client();
  10.     ~Client();
  11.  
  12. public slots:
  13.     void start();
  14.  
  15. signals:
  16.     void done();
  17. }; // Client
  18.  
  19. Client::Client()
  20. {
  21.     QSqlDatabase::addDatabase("QMYSQL", "my_connection");
  22. }
  23.  
  24. Client::~Client()
  25. {
  26. }
  27.  
  28. void Client::start()
  29. {
  30.     // we could do some work here, but for the test simply remove the connection
  31.     QSqlDatabase::removeDatabase("my_connection");
  32.     emit done();
  33. }
  34.  
  35.  
  36. int main(int argc, char* argv[])
  37. {
  38.     QCoreApplication app(argc, argv);
  39.  
  41.     Client client;
  42.     client.moveToThread(&t);
  43.     QObject::connect(&t, SIGNAL(started()), &client, SLOT(start()));
  44.     QObject::connect(&client, SIGNAL(done()), &t, SLOT(quit()));
  45.     QObject::connect(&t, SIGNAL(finished()), &app, SLOT(quit()));
  46.     t.start();
  47.  
  48.     return app.exec();
  49. }
  50.  
  51. #include "main.moc"
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What am I doing wrong?