如何在運行時配置flink作業？

Question

是否可以在運行時配置flink應用程序？ 例如，我有一個流應用程序，該應用程序讀取輸入，進行一些轉換，然后過濾掉低於某個閾值的所有元素。 但是，我希望此閾值在運行時是可配置的，這意味着我可以更改此閾值而不必重新啟動flink作業。 示例代碼：

DataStream<MyModel> myModelDataStream = // get input ...
                // do some stuff ...
                .filter(new RichFilterFunction<MyModel>() {
                    @Override
                    public boolean filter(MyModel value) throws Exception {
                        return value.someValue() > someGlobalState.getThreshold();
                    }
                })
                // write to some sink ...

DataStream<MyConfig> myConfigDataStream = // get input ...
                // ...
                .process(new RichProcessFunction<MyConfig>() {
                      someGlobalState.setThreshold(MyConfig.getThreshold());
                })
                // ...

是否有可能實現這一目標？ 例如，可以通過配置流更改的全局狀態。

Answer 1

是的，您可以使用BroadcastProcessFunction做到這一點。 大概是這樣的：

    MapStateDescriptor<Void, Threshold> bcStateDescriptor = new MapStateDescriptor<>(
    "thresholds", Types.VOID, Threshold.class);

    DataStream<MyModel> myModelDataStream = // get input ...
    DataStream<Threshold> thresholds = // get input...
    BroadcastStream<Threshold> controlStream = thresholds.broadcast(bcStateDescriptor);

    DataStream<MyModel> result = myModelDataStream
      .connect(controlStream)
      .process(new MyFunction());

    public class MyFunction extends BroadcastProcessFunction<MyModel, Long, MyModel> {    
        @Override
        public void processBroadcastElement(Threshold newthreshold, Context ctx, Collector<MyModel> out) {
            BroadcastState<Void, Threshold> bcState = ctx.getBroadcastState(new MapStateDescriptor<>("thresholds", Types.VOID, Threshold.class));  
            bcState.put(null, newthreshold);
        }

        @Override
        public void processElement(MyModel model, Collector<MyModel> out) {
            Threshold threshold = ctx.getBroadcastState(new MapStateDescriptor<>("threshold", Types.VOID, Threshold.class)).get(null);
            if (threshold.value() == null || model.getData() > threshold.value()) {
                out.collect(model);
            }
        }
    }