Like the parallel garbage collector, the concurrent mark-and-sweep collector uses multiple threads. However, this collector is known as a “low-pause” collector because it freezes application threads less frequently, making it more appropriate for user-facing applications where “stop the world” events will cause issues for your users. It can only garbage collect the old generation concurrently, though—it still needs to freeze execution when collecting the young generation. Also, because the collector’s threads execute at the same time as the application’s threads, it does use more processing power than other garbage collectors.
