[jira] [Issue Comment Deleted] (OAK-4780) VersionGarbageCollector should be able to run incrementally

["Julian Reschke (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/OAK-4780?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Julian Reschke updated OAK-4780:
--------------------------------
    Comment: was deleted

(was: bq. At the end of all iterations, the VersionGarbageCollector returns a VersionGCStats that accumulates data from all iterations made. Only the stopwatches are currently not, as Stopwatch lacks methods to add time from other watches. And re-using the same instances in each iteration will show the incorrect data for each iteration. 

The code below works (for some value of "works"):

{noformat}
    public static void main(String[] args) throws InterruptedException {

        final Stopwatch w1 =Stopwatch.createStarted();
        Thread.sleep(123);
        w1.stop();
        System.out.println(w1);

        final Stopwatch w2 =Stopwatch.createStarted();
        Thread.sleep(456);
        w2.stop();
        System.out.println(w2);

        Stopwatch sum = Stopwatch.createStarted(new Ticker() {

            private boolean calledOnce = false;
            @Override
            public long read() {
                if (calledOnce) {
                    return w1.elapsed(TimeUnit.MILLISECONDS) + w2.elapsed(TimeUnit.MILLISECONDS);
                }
                else {
                    calledOnce = true;
                    return 0;
                }
            }
        });
        sum.stop();
        System.out.println(sum);
    }
{noformat})

> VersionGarbageCollector should be able to run incrementally
> -----------------------------------------------------------
>
>                 Key: OAK-4780
>                 URL: https://issues.apache.org/jira/browse/OAK-4780
>             Project: Jackrabbit Oak
>          Issue Type: Task
>          Components: core, documentmk
>            Reporter: Julian Reschke
>         Attachments: leafnodes.diff, leafnodes-v2.diff, leafnodes-v3.diff
>
>
> Right now, the documentmk's version garbage collection runs in several phases.
> It first collects the paths of candidate nodes, and only once this has been successfully finished, starts actually deleting nodes.
> This can be a problem when the regularly scheduled garbage collection is interrupted during the path collection phase, maybe due to other maintenance tasks. On the next run, the number of paths to be collected will be even bigger, thus making it even more likely to fail.
> We should think about a change in the logic that would allow the GC to run in chunks; maybe by partitioning the path space by top level directory.



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