NIO excessive Integer allocation

[Alan Bateman]

Best to being this to nio-dev.


On 31/10/2016 20:20, Jon V. wrote:
> Hi everyone,
>
> EpollSelectorImpl.java #updateSelectedKeys() has a major object creation
> problem.  It creates Integers in order to get the key from the map.
>
> Changing Integer.valueOf() to new Integer() might allow escape-analysis to
> remove the object.
>
> Otherwise, fdToKey could be change to a Map<Number, SelectionKeyImpl> and a
> new mutable Integer class could be created so only a single object would
> need to be created per select() instead of every Key.
>
> /**
>       * Update the keys whose fd's have been selected by the epoll.
>       * Add the ready keys to the ready queue.
>       */
>      private int updateSelectedKeys() {
>          int entries = pollWrapper.updated;
>          int numKeysUpdated = 0;
>          for (int i=0; i<entries; i++) {
>              int nextFD = pollWrapper.getDescriptor(i);
>              SelectionKeyImpl ski = fdToKey.get(Integer.valueOf(nextFD));
>              // ski is null in the case of an interrupt
>              if (ski != null) {
>                  int rOps = pollWrapper.getEventOps(i);
>                  if (selectedKeys.contains(ski)) {
>                      if (ski.channel.translateAndSetReadyOps(rOps, ski)) {
>                          numKeysUpdated++;
>                      }
>                  } else {
>                      ski.channel.translateAndSetReadyOps(rOps, ski);
>                      if ((ski.nioReadyOps() & ski.nioInterestOps()) != 0) {
>                          selectedKeys.add(ski);
>                          numKeysUpdated++;
>                      }
>                  }
>              }
>          }
>          return numKeysUpdated;
>      }