[infinispan-issues] [JBoss JIRA] (ISPN-11176) XSite Max Idle

[Paul Ferraro (Jira)]

    [ https://issues.redhat.com/browse/ISPN-11176?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14362238#comment-14362238 ] 

Paul Ferraro edited comment on ISPN-11176 at 8/8/20 11:36 AM:
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At the last F2F, while discussing locking w/x-site, I brought up the possibility of partitioning entries with a primary site (in the similar way that we partition them within a single cluster).  With this in place, max-idle processing would be initiated only on the primary site for a given entry and cascaded to backup sites accordingly.  It would, however, require that reads from the backup sites "touch" the primary site.  Ideally, reads from a backup site would be rare - and only happen on failure of the primary site.  For normal operation, this strategy has the advantage of minimal x-site traffic and simplifies max-idle processing by using a single authority for determining when to expire a given entry thereby preventing premature expirations.

In the absence of this, however, option 1 seems like the better solution.


was (Author: pferraro):
At the last F2F, while discussing locking w/x-site, I brought up the possibility of partitioning entries with a primary site (in the similar way that we partition them within a single cluster).  With this in place, max-idle processing would be initiated only on the primary site for a given entry and cascaded to backup sites accordingly.  It would, however, require that reads from the backup sites "touch" the primary site.  This strategy has the advantage of minimal x-site traffic (for non-exceptional cases) and simplifies max-idle processing by using a single authority for determining when to expire a given entry thereby preventing premature expirations.

In the absence of this, however, option 1 seems like the better solution.

> XSite Max Idle
> --------------
>
>                 Key: ISPN-11176
>                 URL: https://issues.redhat.com/browse/ISPN-11176
>             Project: Infinispan
>          Issue Type: Enhancement
>          Components: Cross-Site Replication, Expiration
>            Reporter: Will Burns
>            Assignee: Will Burns
>            Priority: Major
>             Fix For: 12.0.0.Final
>
>
> Max idle expiration currently doesn't work with xsite. That is if an entry was written and replicated to both sites but one site never reads the value, but the other does. If they then need to read the value from the other site it will be expired (assuming the max idle time has elapsed).
> There are a few ways we can do this.
> 1. Keep access times local to every site. When a site finds an entry is expired it asks the other site(s) if it has a more recent access. If a site is known to have gone down we should touch all entries, since they may not have updated access times. Requires very little additional xsite communication.
> 2. Batch touch commands and only send every so often. Has window of loss, but should be small. Requires more site usage. Wouldn't work for really low max idle times as an entry could expire before the touch command is replicated.



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