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From "Simon Willnauer (JIRA)" <>
Subject [jira] Commented: (LUCENE-1717) IndexWriter does not properly account for the RAM consumed by pending deletes
Date Thu, 25 Jun 2009 12:57:07 GMT


Simon Willnauer commented on LUCENE-1717:

Regarding buffered delete's RAM usage, accounting an exact number is quite difficult in this
case as there are many strings involved (Terms with field and value) . BufferedDeletes#terms
stores <Term, Num> and BufferedDeletes#queries stores <Query, Num> in both cases
the value part is easy to account while especially for query the memory consumption is hard
to guess similarly the amount of memory a Term takes.

On the other hand I would like to have a notion of memory consumption os BufferedDeletes but
the IndexWriters#setRAMBufferSizeMB javaDoc clearly says that this does not include the memory
used by buffered deletes. I would rather tend to leave it as it is and make it clear in javadoc
/ wiki that setMaxBufferedDeleteTerms is the way to go if you run into memory problems. Feels
quite ambiguous to estimate the memory of buffered deletes.

bq. I think is a good default once we fix the accounting in IndexWriter to properly account
for buffered delete's RAM usage.
is there already an issue to fix the RAM usage? 

> IndexWriter does not properly account for the RAM consumed by pending deletes
> -----------------------------------------------------------------------------
>                 Key: LUCENE-1717
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Bug
>    Affects Versions: 2.4, 2.4.1
>            Reporter: Michael McCandless
>             Fix For: 2.9
>         Attachments: BufferedDeletes_beautification.patch
> IndexWriter, with autoCommit false, is able to carry buffered deletes for quite some
time before materializing them to docIDs (thus freeing up RAM used).
> It's only on triggering a merge (or, commit/close) that the deletes are materialized
and the RAM is freed.
> I expect this in practice is a smallish amount of RAM, but we should still fix it.
> I don't have a patch yet so if someone wants to grab this, feel free!!

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