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https://issues.apache.org/jira/browse/DAFFODIL-2194?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16918014#comment-16918014
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Michael Beckerle commented on DAFFODIL-2194:
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Agree. I recall that the Microsoft BizTalk parser had a tuning parameter around
amount of lookahead, which could be set even to zero which would prevent any
PoUs.
Another way for the cache-limit to work is that if the cache grows sufficiently
past a limit, it serves as a discriminator and all enclosing PoU are marked as
discriminated (literally run up the stack of them, setting them all to true),
at which point a bunch of buffers can be freed. A failure at that point would
then be fatal as there would be no PoU to backtrack to. But a parse could
succeed so long as no backtracking was actually needed.
One challenge with the no-PoU-with-BLOB thing is that it has bad composition
properties. Modifying a schema to replace a hexBinary with a BLOB might cause
the need to rethink the whole way the schema works to avoid the enclosing PoUs.
> buffered data output stream has a chunk limit of 2GB
> ----------------------------------------------------
>
> Key: DAFFODIL-2194
> URL: https://issues.apache.org/jira/browse/DAFFODIL-2194
> Project: Daffodil
> Issue Type: Bug
> Components: Back End
> Reporter: Steve Lawrence
> Assignee: Steve Lawrence
> Priority: Major
> Fix For: 2.5.0
>
>
> A buffered data outupt stream is backed by a growable ByteArrayOutputStream,
> which can only grow to 2GB in size. So if we ever try to write more than 2GB
> to a buffered output stream during unparse (very possible with large blobs),
> we'll get an OutOfMemoryError.
> One potential solution is to be aware of the size of a ByteArrayOutputStream
> when buffering output and automatically create a split when it gets to 2GB in
> sizes. This will still require a ton of memory since we're buffering these in
> memoary, but we'll at least be able to unparse more than 2GB of continuous
> data.
> Note that we should still be able to unparse more than 2GB of data total, as
> long as there so single buffer that's more than 2GB.
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