[jira] [Commented] (DIRMINA-1095) Seems like the management f UDP sessions is really unneficient

["Jonathan Valliere (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DIRMINA-1095?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16633956#comment-16633956 ] 

Jonathan Valliere commented on DIRMINA-1095:
--------------------------------------------

I believe that MINA was designed to operate this way on purpose otherwise changing the SelectionKey interest to WRITE for every single UDP packet might cause a huge performance problem by requiring an epoll_ctrl() call every time.

> Seems like the management f UDP sessions is really unneficient
> --------------------------------------------------------------
>
>                 Key: DIRMINA-1095
>                 URL: https://issues.apache.org/jira/browse/DIRMINA-1095
>             Project: MINA
>          Issue Type: Improvement
>    Affects Versions: 2.0.19
>            Reporter: Emmanuel Lecharny
>            Priority: Major
>             Fix For: 2.0.20
>
>
> When we process incoming UDP messages, we iterate over the activated {{SelectionKey}}s. That's ok, but for each one of them, we read the data and try to flush the scheduled messages. The loop where it's done seems to iterate on *all* the managed sessions, for each keys we are processing :
> {code:java}
>    private void processReadySessions(Set<SelectionKey> handles) {
>         Iterator<SelectionKey> iterator = handles.iterator();
>         while (iterator.hasNext()) {
>             SelectionKey key = iterator.next();
>             DatagramChannel handle = (DatagramChannel) key.channel();
>             iterator.remove();
>             try {
>                 if (key.isValid() && key.isReadable()) {
>                     readHandle(handle);
>                 }
>                 if (key.isValid() && key.isWritable()) {
>                     for (IoSession session : getManagedSessions().values()) {
>                         scheduleFlush((NioSession) session);
> ...
> {code}
> There is no reason to do so. First, we should not iterate on all the managed sessions (we may have thousands), but only the sessions which have something to write, and we certainly should not do that for every active key...



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