[jira] [Updated] (OAK-2124) Trigger compaction after restart to workaround issue due to long running JCR session

["Amit Jain (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/OAK-2124?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Amit Jain updated OAK-2124:
---------------------------
    Fix Version/s:     (was: 1.1)
                   1.1.1

> Trigger compaction after restart to workaround issue due to long running JCR session
> ------------------------------------------------------------------------------------
>
>                 Key: OAK-2124
>                 URL: https://issues.apache.org/jira/browse/OAK-2124
>             Project: Jackrabbit Oak
>          Issue Type: Improvement
>          Components: segmentmk
>            Reporter: Chetan Mehrotra
>             Fix For: 1.0.7, 1.1.1
>
>
> Due to OAK-2045 we cannot perform efficient compaction on a running system as of now. To workaround that an alternative approach can be used
> # Regular maintainence job (invoked via RevisionGC MBean) if determines that compaction would reclaim space above certain threshold then it sets a boolean flag under "compactionStatus" to true along with timestamp
> # Post restart the maintainence job on detecting such a flag can trigger compaction and cleanup
> Or in terms of pseudo code (by [~tmueller] )
> {noformat}
> // this is called once a day in a background thread
> dailyMaintenance() {
>     if (notSegmentNodeStore()) {
>         return;
>     }
>     // this needs to be stored somewhere in the repo
>     lastCompactStart = loadCompactStartFromRepo();
>     if (lastCompactStart > whenThisProcessWasStarted()) {
>         return;
>     }
>     // this can take about 1 minute
>     estimatedSpaceSaved = estimatedSpaceSavedByCompaction();
>     if (estimatedSpaceSaved < minimumSpaceSaved()) {
>         return;
>     }
>     storeLastCompactStartInRepo(now);
>     compact();
> }
> static long CLASS_LOADED_TIME = System.currentTimeMillis();
> whenThisProcessWasStarted() {
>     // a simplification, but maybe good enough
>     return CLASS_LOADED_TIME;
> }
> {noformat}



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