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https://issues.apache.org/jira/browse/LUCENE-2324?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12999244#comment-12999244
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Michael Busch commented on LUCENE-2324:
---------------------------------------
{quote}
Somehow, we have to let each DWPT have some privacy, but, the field name ->
number binding should be "global". I think Simon is going to open a separate
issue to make something possible along these lines...
{quote}
This is done now (LUCENE-2881) and merged into the RT branch.
{quote}
The current plan w/ deletes is that a delete gets buffered 1) into the global
pool (stored in DW and pushed whenever any DWPT flushes), as well as 2) per
DWPT. The per-DWPT pools apply only to the segment flushed from that DWPT,
while the global pool applies during coalescing (ie to all "prior" segments).
{quote}
I implemented and committed this approach. It's looking pretty good - almost
all tests pass. Only TestStressIndexing2 is sometimes failing - but only when
updateDocument() is called, not when I modify the test to only use add,
delete-by-term and delete-by-query.
{quote}
To avoid the full-stop, I think during the flush we can have two global delete
pools. We carefully sweep all DWPTs and flush each, in succession. Any DWPT not
yet flushed is free to continue indexing as normal, putting deletes into the
first global pool, flushing as normal. But, a DWPT that has been flushed by the
"sweeper" must instead put deletes for an updateDocument carefully into the 2nd
pool, and not buffer the delete into DWPTs not yet flushed.
{quote}
I haven't done this yet - it might fix the failing test I described.
> Per thread DocumentsWriters that write their own private segments
> -----------------------------------------------------------------
>
> Key: LUCENE-2324
> URL: https://issues.apache.org/jira/browse/LUCENE-2324
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Reporter: Michael Busch
> Assignee: Michael Busch
> Priority: Minor
> Fix For: Realtime Branch
>
> Attachments: LUCENE-2324-SMALL.patch, LUCENE-2324-SMALL.patch,
> LUCENE-2324-SMALL.patch, LUCENE-2324-SMALL.patch, LUCENE-2324-SMALL.patch,
> LUCENE-2324.patch, LUCENE-2324.patch, LUCENE-2324.patch, LUCENE-2324.patch,
> lucene-2324.patch, lucene-2324.patch, test.out, test.out, test.out, test.out
>
>
> See LUCENE-2293 for motivation and more details.
> I'm copying here Mike's summary he posted on 2293:
> Change the approach for how we buffer in RAM to a more isolated
> approach, whereby IW has N fully independent RAM segments
> in-process and when a doc needs to be indexed it's added to one of
> them. Each segment would also write its own doc stores and
> "normal" segment merging (not the inefficient merge we now do on
> flush) would merge them. This should be a good simplification in
> the chain (eg maybe we can remove the *PerThread classes). The
> segments can flush independently, letting us make much better
> concurrent use of IO & CPU.
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