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https://issues.apache.org/jira/browse/LUCENE-2075?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12779253#action_12779253
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Mark Miller commented on LUCENE-2075:
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bq. Well, that's just hosted on code.google.com (ie it's not "Google's"),
Ah - got that vibe, but it didn't really hit me.
bq. though they do state that they created a "Production Version"
Right - thats what I was thinking we might try. Though the whole, trying this
from scratch to learn is a bit scary too ;) But hey, I'm not recommending, just
perhaps trying it.
bq. I think FastLRUCache is probably best for Lucene, because it scales up well
w/ high number of threads?
Indeed - though if we expect a low hit ratio, we might still compare it with
regular old synchronized LinkedHashMap to be sure. In certain cases, puts
become quite expensive I think.
bq. It looks like ConcurrentLRUCache (used by FastLRUCache, but the latter does
other solr-specific things) is the right low-level one to use for Lucene?
Right.
> Share the Term -> TermInfo cache across threads
> -----------------------------------------------
>
> Key: LUCENE-2075
> URL: https://issues.apache.org/jira/browse/LUCENE-2075
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Reporter: Michael McCandless
> Priority: Minor
> Fix For: 3.1
>
> Attachments: ConcurrentLRUCache.java
>
>
> Right now each thread creates its own (thread private) SimpleLRUCache,
> holding up to 1024 terms.
> This is rather wasteful, since if there are a high number of threads
> that come through Lucene, you're multiplying the RAM usage. You're
> also cutting way back on likelihood of a cache hit (except the known
> multiple times we lookup a term within-query, which uses one thread).
> In NRT search we open new SegmentReaders (on tiny segments) often
> which each thread must then spend CPU/RAM creating & populating.
> Now that we are on 1.5 we can use java.util.concurrent.*, eg
> ConcurrentHashMap. One simple approach could be a double-barrel LRU
> cache, using 2 maps (primary, secondary). You check the cache by
> first checking primary; if that's a miss, you check secondary and if
> you get a hit you promote it to primary. Once primary is full you
> clear secondary and swap them.
> Or... any other suggested approach?
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