Github user vipul1409 commented on a diff in the pull request:
https://github.com/apache/flink/pull/2922#discussion_r90598293
--- Diff:
flink-contrib/flink-streaming-contrib/src/main/java/org/apache/flink/contrib/streaming/MultiThreadedFlatMapFunction.java
---
@@ -0,0 +1,91 @@
+package org.apache.flink.contrib.streaming;
+
+import org.apache.flink.api.common.functions.FlatMapFunction;
+import org.apache.flink.api.common.functions.RichFlatMapFunction;
+import org.apache.flink.api.common.functions.util.ListCollector;
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.runtime.util.NamedThreadFactory;
+import org.apache.flink.util.Collector;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.*;
+
+/**
+ * Created by vipulmodi on 11/30/16.
+ */
+
+//To return Futures to calling fucntion we can do OUT extends Future.
+public class MultiThreadedFlatMapFunction<IN, OUT> extends
RichFlatMapFunction<IN, OUT> {
+
+ private static final long serialVersionUID;
+ private ExecutorService flatMapExecutors;
+ private Integer numberOfthreads;
+ private List<Callable<ArrayList<OUT>>> callables;
+ private List<Future<ArrayList<OUT>>> futures;
+ static {
+ serialVersionUID = 1L;
+ }
+
+ public FlatMapFunction flatMapFunction;
+
+ public MultiThreadedFlatMapFunction(FlatMapFunction flatMapFunction,
Integer numberOfthreads) {
+ this.flatMapFunction = flatMapFunction;
+ this.numberOfthreads = numberOfthreads;
+ this.callables = new ArrayList<>();
+ this.futures = new ArrayList<>();
+ }
+
+ // Understand side effects of making out final.
+ @Override
+ public void flatMap(final IN value, final Collector<OUT> out) throws
Exception {
+ // Figure out a better way to call
+ /*callables.add(new Callable<ArrayList<OUT>>() {
+ @Override
+ public ArrayList<OUT> call() throws Exception {
+ ArrayList<OUT> result = new ArrayList<OUT>();
+ Collector<OUT> collector = new ListCollector<OUT>(result);
+ flatMapFunction.flatMap(value, collector);
+ return result;
+ }
+ });*/
+
+ futures.add(flatMapExecutors.submit(new Callable<ArrayList<OUT>>()
{
+ @Override
+ public ArrayList<OUT> call() throws Exception {
+ ArrayList<OUT> result = new ArrayList<OUT>();
--- End diff --
As each call may take significant time we need to ensure that all the
results objects of active threads can stay in memory.
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