[FLINK-24558] dataStream can not use multiple classloaders

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Won't Fix
• Component/s: Command Line Client
• Labels: pull-request-available stale-assigned
• Assignee: bai sui
• Reporter: bai sui
• Created: 15/Oct/21 04:26
• Updated: 11/Nov/22 15:39
• Resolved: 11/Nov/22 15:39

Description

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

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();
    }
}

Issue Links

• links to: GitHub Pull Request #17521