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https://issues.apache.org/jira/browse/DIRMINA-1078?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16368890#comment-16368890
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Guus der Kinderen commented on DIRMINA-1078:
--------------------------------------------
Thanks for the feedback guys! I initially had this as a separate {{Executor}},
exactly for the reasons that you mention. You can see this variant of the code
here:
https://github.com/guusdk/mina/commit/c0a421cf445696fbfd4d5b10d650d7c71d8faab7
(note that I fixed a bug later on - don't blindly use this version!)
There was a _lot_ of code duplication going on. I thought about creating an
abstract base class from which this implementation, but also
{{OrderedThreadPoolExecutor}} would extend - but that proved to much of a
hassle.
With the patch that I introduced, I believe I was able to add the new
functionality to the existing implementation of {{OrderedThreadPoolExecutor}},
as a completely _optional_, _not enabled by default_ behavior, that introduces
next to _no behavioral changes_ if unused. Given this, I would personally
prefer my addition to remain in {{OrderedThreadPoolExecutor}} instead of
introducing a different {{ThreadPool}} implementation, but that's not a hill
I'm willing to die on.
[~johnnyv], the {{FIFOEntry}} implementation is used as a tie-breaker, in case
the {{Comparator}} that is provided does not distinguish between the sessions.
It arguably can be left out, but I'd prefer to keep it in: It allows one to use
relatively simple {{Comparator}} implementations, while still be ensured of
defined behavior for those elements that are not covered in the {{Comparator}}.
Again, not a hill I'm willing to die on though.
[~elecharny], if you're willing to transform my patch into a separate
{{Executor}} (in case my arguments above were not compelling), please, be my
guest. If anything, it'd save me time, and having a second set of eyes looking
at this code will not hurt either.
> OrderedThreadPoolExecutor should allow sessions to be prioritized
> -----------------------------------------------------------------
>
> Key: DIRMINA-1078
> URL: https://issues.apache.org/jira/browse/DIRMINA-1078
> Project: MINA
> Issue Type: New Feature
> Components: Core
> Reporter: Guus der Kinderen
> Priority: Minor
> Attachments: 20180216.patch
>
>
> The functionality provided in {{OrderedThreadPoolExecutor}} should be
> augmented to, optionally, allow for assignment of priority to certain
> sessions over others.
> We've introduced this functionality after observing issues in a deployment
> where system resources where being starved by the sheer amount of sessions
> that attempted to perform TLS. Without the class introduced by this commit,
> events for any session could eventually fail (time-out), causing the session
> to fail. If that session happened to be a session that had already
> established TLS, the resources that were spent on establishing TLS are
> wasted. The negative effect is amplified by the fact that a typical client in
> such a situation would attempt
> to reconnect, which further adds to the load of the system already being
> starved.
> With the modifications introduced by the patch provided in this issue,
> priority can be given to sessions that have already established TLS. This
> dramatically reduces the issue described above, as the first sessions to fail
> will be those that are still negotiating TLS. Using a specialized
> {{Comparator}}, one can even prioritize between these, causing sessions for
> which least effort has performed to fail before sessions that are more likely
> to near TLS completion.
> The patch intends to add this feature as optional functionality to the
> existing implementation, with little side effects to the existing, default
> behavior.
> The implementation provided here was initially based on a copy of the
> implementation of {{OrderedThreadPoolExecutor}} that introduced a
> considerable amount of code duplication. For illustrative purposes, the line
> of commits leading from that initial commit to the patch attached to this
> JIRA issue can be found at
> [https://github.com/guusdk/mina/commit/c0a421cf445696fbfd4d5b10d650d7c71d8faab7]
> and later commits.
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