More than a million people joined raucous protests across France this week, demanding the repeal of a new labor law. In Paris, some 80,000 demonstrators pried up cobblestones, tore down street signs, and ripped out park benches, hurling items at police. Demonstrators blocked roads and train tracks across the country. Hundreds were arrested, bringing to 3,500 the number taken into custody during the past two weeks. With tensions mounting, officials from the ruling center-right party of President Jacques Chirac began meeting with union leaders to discuss amending the law, which allows companies to fire at will workers under age 26 in their first two years on the job. The probation period is meant to encourage firms to hire more young workers, who face unemployment of more than 20 percent.