title: What is the difference between G1GC options -XX:ParallelGCThreads vs -XX:ConcGCThreads
body: <p>when configuring the G1GC 
  we have 2 kinds of thread count 
  -XX:ParallelGCThreads and  -XX:ConcGCThreads
  what is the difference, how they are going to impact, 
  any reference is appreciated.</p>