Guus der Kinderen created DIRMINA-1078:
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Summary: 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
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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