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https://issues.apache.org/jira/browse/NIFI-11636?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mark Payne updated NIFI-11636:
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Assignee: Mark Payne
Status: Patch Available (was: Open)
> ParquetReader buffers up to 2 GB of content into heap unnecessarily
> -------------------------------------------------------------------
>
> Key: NIFI-11636
> URL: https://issues.apache.org/jira/browse/NIFI-11636
> Project: Apache NiFi
> Issue Type: Bug
> Components: Extensions
> Reporter: Mark Payne
> Assignee: Mark Payne
> Priority: Major
> Fix For: 1.latest, 2.latest
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> The Parquet Record Reader uses the NiFiSeekableInputStream. Because Parquet
> requires reading the footer first, this class is intended to use
> {{mark/reset}} so that we can read the footer and then reset back to the
> beginning.
> To achieve this, it calls {{InputStream.mark(Integer.MAX_VALUE)}} which will
> buffer up to 2 GB onto heap. However, the underlying InputStream is the
> ContentClaimInputStream. The ContentClaimInputStream has smarts built into it
> to allow resetting without having to buffer content into memory. In
> particular, if you read over the {{limit}} provided and then call {{reset}}
> it will close the InputStream and open a new InputStream from the beginning
> of the FlowFIle content and seek to the desired offset.
> Because of this, we don't need to use {{InputStream.mark(Integer.MAX_VALUE)}}
> and can instead use {{InputStream.mark(8192)}} or some similarly small value.
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