title: Difference between -XX:+UseParallelGC and -XX:+UseParNewGC
body: <p>They are algorithms for the young generation garbage collection. </p>
  
  <p>The second one (UseParNewGC) gets activated automatically with the concurrent tenured generation garbage collection (see <a href="https://stackoverflow.com/questions/220388/java-concurrent-and-parallel-gc">Java Concurrent and Parallel GC</a>) but, is there a difference between the two parallel algorithms?</p>