[GitHub] [zookeeper] lanicc commented on pull request #1578: ZOOKEEPER-4057: NIOServerCnxnFactory.selectorThreads,using List instead of HashSet

[GitBox <gi...@apache.org>]

lanicc commented on pull request #1578:
URL: https://github.com/apache/zookeeper/pull/1578#issuecomment-768125661


   simple test:
   
   `public static void main(String[] args) {
           int numObj = 1;
   
           Set<Object> set = new HashSet<>();
           for (int i = 0; i < numObj; i++) {
               set.add(new Object());
           }
           System.out.println("Size of HashSet: " + GraphLayout.parseInstance(set).totalSize());
           List<Object> list = new ArrayList<>();
           for (int i = 0; i < numObj; i++) {
               list.add(new Object());
           }
           System.out.println("Size of ArrayList: " + GraphLayout.parseInstance(list).totalSize());
   
   
           long start, end;
   
           Iterator<Object> setIterator = set.iterator();
           start = System.nanoTime();
           while (setIterator.hasNext()) {
               setIterator.next();
           }
           end = System.nanoTime();
           System.out.println("HashSet iterator cost: " + (end - start));
   
           Iterator<Object> listIterator = list.iterator();
           start = System.nanoTime();
           while (listIterator.hasNext()) {
               listIterator.next();
           }
           end = System.nanoTime();
           System.out.println("ArrayList iterator cost: " + (end - start));
       }`
   
   result:
   
   _Size of HashSet: 256
   Size of ArrayList: 112
   HashSet iterator cost: 20474
   ArrayList iterator cost: 460_
   


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