public void Synchronize()
{
    _logger.Log.Info("Synchronization started.");
    Thread.Sleep(new TimeSpan(0, 5, 0));
    _logger.Log.Info("Synchronization finished.");
}

public void Synchronize()
{
    lock (SynchronizeLock)
    {
        _logger.Log.Info("Synchronization started.");
        Thread.Sleep(new TimeSpan(0, 5, 0));
        _logger.Log.Info("Synchronization finished.");
    }
}