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https://issues.apache.org/jira/browse/FLINK-27621?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17537317#comment-17537317
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Shengkai Fang commented on FLINK-27621:
---------------------------------------
I am +1 for this feature. Let me share some thoughs about this.
In many cases, we need add jar or remove jar for the user classloader in the
interactive gateway. For example, user can
```
Flink SQL> ADD JAR 'path'; -- path to
Flink SQL> SELECT udf(field) from mytable; -- SUBMIT the job
Flink SQL > ADD JAR 'path_to_connector'
Flink SQL > INSERT INTO sink_in_added_jar SELECT udf(field) from mytable;
```
But currently we just create a new classloader when the user add jar or remove
jar in the SQL Client side. However, create a new classloader doesn't mean the
classes that are loaded by the old classloader will be collected. Actually
unloading the classes is not an easy work. It requires no one refers to the
classes that loaded by the old classloader. However, it relies on the usage
and dependencies. For example, one class(e.g. Hadoop Configuration) is loaded
by the app classloader and it caches the class(e.g. connector class) loaded by
the child classloader. If the cache is not cleared, the old classloader can not
be collected.
With this feature, we are able to reuse the classloader per session and reduce
the possiblities of the OOM.
> expose SafetyNetWrapperClassLoader from private to public and add addUrl
> method for flink client
> ------------------------------------------------------------------------------------------------
>
> Key: FLINK-27621
> URL: https://issues.apache.org/jira/browse/FLINK-27621
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Task
> Affects Versions: 1.16.0
> Reporter: jackylau
> Priority: Major
> Fix For: 1.16.0
>
>
> expose SafetyNetWrapperClassLoader from private to public and add addUrl
> method for flink client when user need dynamic add jars
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