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https://issues.apache.org/jira/browse/LUCENE-2324?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12859387#action_12859387
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Michael McCandless commented on LUCENE-2324:
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{quote}
Sounds like we use the current thread affinity system (ie, a
hash map), that when the max threads is reached, new threads get
kind of round robined onto existing DWPTs?
{quote}
Yeah something along those lines... and clearing out all mappings for
a given DWPT when it flushes.
{quote}
bq. if RAM usage grows too much beyond your first trigger and before that first
flush has finished, start a 2nd DWPT flushing, etc.
What's the definition of the "too much" portion of the above
statement?
{quote}
We could do something simple, eg, at 90% RAM used, you flush your
first DWPT. At 110% RAM used, you flush all DWPTs. And take linear
steps in between?
EG if I have 5 DWPTs, I'd flush first one at 90%, 2nd at 95%, 3rd at
100%, 4th at 105% and 5th at 110%.
Of course, if flushing is fast, then RAM is quickly freed up, then we
only flush 1 DWPT at a time... we only need these tiers to
self-regulate RAM consumed from ongoing indexing vs time it takes to
do the flush.
> 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: 3.1
>
> Attachments: lucene-2324.patch, LUCENE-2324.patch
>
>
> 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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