[infinispan-issues] [JBoss JIRA] (ISPN-6706) Purging cache writers is [mostly] redundant when eviction is disabled and preload is enabled

[William Burns (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-6706?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13242646#comment-13242646 ] 

William Burns commented on ISPN-6706:
-------------------------------------

I actually created ISPN-6710 and ISPN-6711.

Yes they are doing SELECT or DELETE.  Unfortunately I was looking at JdbcBinaryStore which does what I said, but JdbcStringStore is doing a straight DELETE from the DB.  This means that JdbcStringStore will not notify listeners of an entry being expired.  I don't know if you are relying on that.

> Purging cache writers is [mostly] redundant when eviction is disabled and preload is enabled
> --------------------------------------------------------------------------------------------
>
>                 Key: ISPN-6706
>                 URL: https://issues.jboss.org/browse/ISPN-6706
>             Project: Infinispan
>          Issue Type: Enhancement
>          Components: Loaders and Stores
>    Affects Versions: 8.2.2.Final
>            Reporter: Krzysztof Sobolewski
>
> This issue arised when I was testing a cluster with about 16 million entries. Our configuration is that all the data is also kept in memory, so eviction is disabled in this cache. But expiration is enabled. During the test I noticed pauses that started small but increased while the test was progressing, reaching more than 20 seconds at one point. After ruling out maintenance tasks in MySQL that could interfere, I discovered that the pause is caused by the expiration thread purging the database for expired entries. This was a huge and unnecessary drag so I hacked Infinispan to skip the purge of persistent state in cases when it's likely to be redundant with purging the transient state. I say "likely" because entries evicted maually via the evict() call poke a huge hole in the underlying assumptions :) Anyway, our cluster no longer regularly pauses for half a minute, so here's something for your consideration.



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