[jboss-jira] [JBoss JIRA] Commented: (JGRP-1051) TimeScheduler: replace use of ScheduledThreadPoolExecutor with ConcurrentSkipListMap

[Bela Ban (JIRA)]

    [ https://jira.jboss.org/jira/browse/JGRP-1051?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12486292#action_12486292 ] 

Bela Ban commented on JGRP-1051:
--------------------------------

Yes, this is something I wanted to do as an optimization:

- Var sleep-time which is the time ofthe first element (next to be executed)
- When a new task is schedule, do a sleep_time=min(sleep_time, next_task.delay)
- If the new sleep_time is lower than the current, interrupt and reschedule the runner

> TimeScheduler: replace use of ScheduledThreadPoolExecutor with ConcurrentSkipListMap
> ------------------------------------------------------------------------------------
>
>                 Key: JGRP-1051
>                 URL: https://jira.jboss.org/jira/browse/JGRP-1051
>             Project: JGroups
>          Issue Type: Feature Request
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 2.9
>
>         Attachments: TimeScheduler.java
>
>
> TimeScheduler currently extends ScheduledThreadPoolExecutor, which uses a DelayQueue for keeping an ordered list of tasks (ordered by their execution times).
> DelayQueue doesn't provide good speed, e.g. (IIRC) remove() requires a linear list scan.
> ConcurrentSkipListMap however provides O(log(n)) cost for get(), put(), remove() and containsKey(). Attached is a cursory impl of TimeScheduler based on ConcurrentSkipListMap. It is faster than the old version.
> Since ConcurrentSkipListMap requires JDK 1.6, we cannot use this in 2.6.x. It can be used in 3.0 only, or perhaps - after a discussion on the mailing list - in 2.9...

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