[jira] [Updated] (LUCENE-5885) MergeScheduler should not implement Closeable

["Shai Erera (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-5885?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Shai Erera updated LUCENE-5885:
-------------------------------

    Attachment: LUCENE-5885.patch

Patch removes CMS.sync() and Closeable from MergeScheduler. Note that this cannot be committed yet, since it depends on the fix Mike's working on on LUCENE-5871. Currently, without that fix, when you call IW.close() and commitOnClose=true, IW flushes, finishes merges and then commits. But that commit may spawn merges itself, and so if we don't wait/abort them in IW.rollbackInternal, some tests complain about still running merges, or hit AlreadyClosedExceptions. With the fix on LUCENE-5871, that commit won't spawn new merges, which is silly since IW is closing...

I'll wait for that fix before I assert this patch really works. I also didn't add a CHANGES entry - the migration from CMS.sync() is to simply call IW.waitForMerges(), which I think is better to do anyway.

> MergeScheduler should not implement Closeable
> ---------------------------------------------
>
>                 Key: LUCENE-5885
>                 URL: https://issues.apache.org/jira/browse/LUCENE-5885
>             Project: Lucene - Core
>          Issue Type: Bug
>          Components: core/index
>            Reporter: Shai Erera
>         Attachments: LUCENE-5885.patch
>
>
> MergeScheduler implements Closeable and IndexWriter calls ms.close() when it's closed. But MergeScheduler can be shared between several writers, which means closing it by any particular writer is wrong. We should rather implement some ref-counting logic such that each IW will call incRef() in the ctor, and decRef() on close(), and MergeScheduler will truly close when the ref-count hits 0.
> As it is now, if you share a MergeScheduler between writers and close() does something terminating, I doubt if it really works.
> Also, when I look at ConcurrentMergeScheduler.close(), it calls sync() which joins all MergeThreads. But if that CMS instance is shared between few IWs, doesn't it mean that a single IW calling close() waits on MergeThreads that execute merges of other IWs!?!? This seems ... wrong?



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