[jboss-jira] [JBoss JIRA] (WFLY-12581) Optimize distributed web/ejb expiration schedulers

[Paul Ferraro (Jira)]

     [ https://issues.jboss.org/browse/WFLY-12581?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul Ferraro updated WFLY-12581:
--------------------------------
    Attachment: Schedulers for local workloads.png


> Optimize distributed web/ejb expiration schedulers
> --------------------------------------------------
>
>                 Key: WFLY-12581
>                 URL: https://issues.jboss.org/browse/WFLY-12581
>             Project: WildFly
>          Issue Type: Enhancement
>          Components: Clustering
>    Affects Versions: 18.0.0.Beta1
>            Reporter: Paul Ferraro
>            Assignee: Paul Ferraro
>            Priority: Major
>         Attachments: Schedulers for distributed workloads.png, Schedulers for local workloads.png
>
>
> WF18 added a new expiration scheduler implementation for SFSBs specifically optimized for non-distributed environments.  The key features of this implementations are:
> * Uses a single scheduled task instead of a scheduled task per SFSB
> * Uses a double-linked list to track SFSBs to be expired
> The use of a linked queue is based on the following assumptions:
> # All SFSB using a given scheduler share the same @StatefulTimeout
> # A given call to Scheduler.schedule(...) is always the last item to be scheduled
> Distributed SFSBs cannot use the same implementation because the second assumption is not valid, as a member may assume the responsibility of expiring a SFSB previously owned by another member.  They can, however, leverage the strategy of using a single scheduled task instead of a task per SFSB.  Due to the nature of the scheduler, that most scheduled tasks will be cancelled/removed and rescheduled, this strategy outperforms the current implementation.
> This jira proposes the following:
> * Generalize the Scheduler interface for reuse between SFSBs and web sessions.
> * Generalize the new local scheduler implementation such that the same scheduler can support both local and distributed SFSBs using different queue implementations for tracking scheduled items
> * Distributed use case uses a PriorityBlockingQueue, which has O(log N) add/remove characteristics
> * Replace ExpirationTracker with a ConcurrentDirectDeque to support local case, which has O(1) add/remove characteristics
> ** ConcurrentDirectDeque outperforms ExpirationTracker under concurrent load
> Local web session expiration cannot use the same expiration scheduler used by local SFSBs because the first assumption is not valid, since a given web session can override the default max inactive interval.  However, we can still optimize the local web session case by delegating expiration to the PriorityBlockingQueue-based implementation if the session uses a non-default max inactive interval, and to the ConcurrentDirectDeque-based implementation if the session uses the default max inactive interval.



--
This message was sent by Atlassian Jira
(v7.13.8#713008)