[jira] [Updated] (NIFI-10111) When unpacking NARs, provide ability to unpack into uber jar to avoid using too many open file handles

["Mark Payne (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/NIFI-10111?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mark Payne updated NIFI-10111:
------------------------------
    Status: Patch Available  (was: Open)

> When unpacking NARs, provide ability to unpack into uber jar to avoid using too many open file handles
> ------------------------------------------------------------------------------------------------------
>
>                 Key: NIFI-10111
>                 URL: https://issues.apache.org/jira/browse/NIFI-10111
>             Project: Apache NiFi
>          Issue Type: Improvement
>          Components: Core Framework, Documentation & Website, NiFi Stateless
>            Reporter: Mark Payne
>            Assignee: Mark Payne
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> When we unpack a NAR file, we expand all .jar files within it into the working directory. We then create a NAR ClassLoader for the NAR. The NAR ClassLoader extends URLClassLoader. As a result, we end up with a ClassLoader that holds an open file handle for every JAR file (and potentially other files) that gets unpacked.
> This can result in NiFi needing to use a lot of open file handles.
> When using Stateless NiFi, this is of particular concern, as it may need to run in more constrained environments, since it's intended to be embedded.
> We can significantly reduce the number of open file handles by unpacking each NAR into a single "Uber Jar File" instead of individual files. While this is particularly of concern for for Stateless NiFi, it may provide benefits to NiFi also. But for NiFi, it should not be "on by default". Users should have to opt into it via an entry in nifi.properties.



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