Europe has an immigrant-problem. The problem can be summarized as follows: Invite millions and millions of people to live in your country. Pay them so much social-welfare that they don't even think about entering the job-market. Lock them up in special ghettoes so they wont have any relations to the natives. Stamp on their religion and show them that they are not the norm in the country they live in. Raise a few generations like this. Then you have a problem.
The French riots are not a shocking event. They are the social-democratic immigrant-policy in action. They are one more step in French's downfall as an economic power in the world. They are the results from 50 years of European Leftism.