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https://issues.apache.org/jira/browse/LUCENE-5875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14092849#comment-14092849
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Christian Ziech commented on LUCENE-5875:
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Exactly - when the PagedGrowableWriter in the NodeHash used 1<<27 bytes for a
page things worked like a charm (with maxint as suffix length,
doShareNonSingletonNodes set to true and both of the min suffix counts set to
0).
What numbers are you interested in? With "doShareSuffix" enabled the FST takes
3.1 GB of disk space: I quickly fetched the following numbers:
- arcCount: 561802889
- nodeCount: 291569846
- arcWithOutputCount: 201469018
While in theory the nodeCount should hence be lower than 2.1B I think we also
got an exception when enabling packing. But I'm not sure if we tried it in
conjunction with doShareSuffix.
> Default page/block sizes in the FST package can cause OOMs
> ----------------------------------------------------------
>
> Key: LUCENE-5875
> URL: https://issues.apache.org/jira/browse/LUCENE-5875
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/FSTs
> Affects Versions: 4.9
> Reporter: Christian Ziech
> Priority: Minor
>
> We are building some fairly big FSTs (the biggest one having about 500M terms
> with an average of 20 characters per term) and that works very well so far.
> The problem is just that we can use neither the "doShareSuffix" nor the
> "doPackFST" option from the builder since both would cause us to get
> exceptions. One beeing an OOM and the other an IllegalArgumentException for a
> negative array size in ArrayUtil.
> The thing here is that we in theory still have far more than enough memory
> available but it seems that java for some reason cannot allocate byte or long
> arrays of the size the NodeHash needs (maybe fragmentation?).
> Reducing the constant in the NodeHash from 1<<30 to e.g. 27 seems to fix the
> issue mostly. Could e.g. the Builder pass through its bytesPageBits to the
> NodeHash or could we get a custom parameter for that?
> The other problem we run into was a NegativeArraySizeException when we try to
> pack the FST. It seems that we overflowed to 0x80000000. Unfortunately I
> accidentally overwrote that exception but I remember it was triggered by the
> GrowableWriter for the inCounts in line 728 of the FST. If it helps I can try
> to reproduce it.
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