[jira] [Comment Edited] (FLINK-24558) dataStream can not use multiple classloaders

["bai sui (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-24558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17430390#comment-17430390 ] 

bai sui edited comment on FLINK-24558 at 10/19/21, 8:17 AM:
------------------------------------------------------------

 TO:@Arvid Heise @Caizhi Weng
  
 thanks for your reply, as the stream api code become more and more complicated, we will add more dependenies from  third pary. 
  
 This kind of problem will be inevitable. If we only rely on this kind of trick like shade the dependencies  to solve this kind of problem, I think it is far from enough . 
 There should be a work-and-for-all solution. I proposed a plan for discussion，the figure show as below：
  
 !Flink ClassLoader优化 (1).png!
 * make server side classLoader which create by BloblibraryCacheManager.DefaultClassLoaderFactorypluggable in able to make the parent classloader of  ChildFirstClassLoader variable
 * the parent classloader facade client side multi classloader for class finding by polling
  
 how about it , thanks


was (Author: baisui):
 
TO:@Arvid Heise @Caizhi Weng
 
thanks for your reply, as the stream api code become more and more complicated, we will add more dependenies from  third pary. 
 
This kind of problem will be inevitable. If we only rely on this kind of trick like shade the dependencies  to solve this kind of problem, I think it is far from enough . 
There should be a work-and-for-all solution. I proposed a plan for discussion，the figure show as below：
 
!Flink ClassLoader优化 (1).png!
  * 
make server side classLoader which create by BloblibraryCacheManager.DefaultClassLoaderFactorypluggable in able to make the parent classloader of  ChildFirstClassLoader variable
 * 
the parent classloader facade client side multi classloader for class finding by polling
 
how about it , thanks

> dataStream can not use multiple classloaders 
> ---------------------------------------------
>
>                 Key: FLINK-24558
>                 URL: https://issues.apache.org/jira/browse/FLINK-24558
>             Project: Flink
>          Issue Type: Improvement
>          Components: API / DataStream
>            Reporter: bai sui
>            Priority: Minor
>         Attachments: Flink ClassLoader优化 (1).png
>
>
> create a dataStream demo as below，in the demo，create a very simple example，
> read stream data from sourceFunction，and send it to sinkFunction without any processing.
> The point is，by creating the instance of SourceFunction and SinkFunction has used two separately URLClassLoader with different dependencies,for avoiding the code conflict .
> but the problem is flink client send to server ,the server side throw an classNotFoundException which defined the de classloader dependencies, Obviously the server side has not use the classloader as client side.
> how can I solve the problem ，is there any one can give me some advice ？ thanks a lot 
>  
> {code:java}
> public class FlinkStreamDemo {
>     public static void main(String[] args) throws Exception {
>         StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
>         SourceFunction<DTO> sourceFunc = createSourceFunction();
>         DataStreamSource<DTO> dtoDataStreamSource = env.addSource(sourceFunc);
>         SinkFunction<DTO> sinkFunction = createSink();
>         dtoDataStreamSource.addSink(sinkFunction);
>         env.execute("flink-example");
>     }
>     private static SinkFunction<DTO> createSink() {
>         URL[] urls = new URL[]{...};
>         ClassLoader classLoader = new URLClassLoader(urls);
>         ServiceLoader<ISinkFunctionFactory> loaders = ServiceLoader.load(ISinkFunctionFactory.class, classLoader);
>         Iterator<ISinkFunctionFactory> it = loaders.iterator();
>         if (it.hasNext()) {
>             return it.next().create();
>         }
>         throw new IllegalStateException();
>     }
>     private static SourceFunction<DTO> createSourceFunction() {
>         URL[] urls = new URL[]{...};
>         ClassLoader classLoader = new URLClassLoader(urls);
>         ServiceLoader<ISourceFunctionFactory> loaders = ServiceLoader.load(ISourceFunctionFactory.class, classLoader);
>         Iterator<ISourceFunctionFactory> it = loaders.iterator();
>         if (it.hasNext()) {
>             return it.next().create();
>         }
>         throw new IllegalStateException();
>     }
>     public interface ISinkFunctionFactory {
>         SinkFunction<DTO> create();
>     }
>     public interface ISourceFunctionFactory {
>         SourceFunction<DTO> create();
>     }
> }
> {code}



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