This class is used to execute tasks in Java. Generally, users will not directly create a ThreadPoolExecutor, but instead use one of the the static factory methods in `Executors` to create one. For example:

class Runner {
 
  private final ExecutorService executor = Executors.newCachedThreadPool();
 
  public void run(Runnable r) {
    executor.execute(r);
  }
}