Github user aalexandrov commented on a diff in the pull request:
https://github.com/apache/flink/pull/605#discussion_r28818529
--- Diff:
flink-contrib/src/test/java/org/apache/flink/contrib/operatorstatistics/OperatorStatsAccumulatorsTest.java
---
@@ -0,0 +1,144 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.contrib.operatorstatistics;
+
+import org.apache.flink.api.common.JobExecutionResult;
+import org.apache.flink.api.common.accumulators.Accumulator;
+import org.apache.flink.api.common.functions.RichFlatMapFunction;
+import org.apache.flink.api.java.ExecutionEnvironment;
+import org.apache.flink.api.java.io.DiscardingOutputFormat;
+import org.apache.flink.api.java.tuple.Tuple1;
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.test.util.AbstractTestBase;
+import org.apache.flink.util.Collector;
+import org.junit.Assert;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.Serializable;
+import java.util.Map;
+import java.util.Random;
+
+public class OperatorStatsAccumulatorsTest extends AbstractTestBase {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(OperatorStatsAccumulatorsTest.class);
+
+ private static final String ACCUMULATOR_NAME = "op-stats";
+
+ public OperatorStatsAccumulatorsTest(){
+ super(new Configuration());
+ }
+
+ @Test
+ public void testAccumulator() throws Exception {
+
+ String input = "";
+
+ Random rand = new Random();
+
+ for (int i = 1; i < 1000; i++) {
+ if(rand.nextDouble()<0.2){
+ input+=String.valueOf(rand.nextInt(5))+"\n";
+ }else{
+ input+=String.valueOf(rand.nextInt(100))+"\n";
+ }
+ }
+
+ String inputFile = createTempFile("datapoints.txt", input);
+
+ ExecutionEnvironment env =
ExecutionEnvironment.getExecutionEnvironment();
+
+ env.readTextFile(inputFile).
+ flatMap(new StringToInt()).
+ output(new
DiscardingOutputFormat<Tuple1<Integer>>());
+
+ JobExecutionResult result = env.execute();
+
+ OperatorStatistics globalStats =
result.getAccumulatorResult(ACCUMULATOR_NAME);
+ LOG.debug("Global Stats");
+ LOG.debug(globalStats.toString());
+
+ OperatorStatistics merged = null;
+
+ Map<String,Object> accResults =
result.getAllAccumulatorResults();
+ for (String accumulatorName:accResults.keySet()){
+ if (accumulatorName.contains(ACCUMULATOR_NAME+"-")){
+ OperatorStatistics localStats =
(OperatorStatistics) accResults.get(accumulatorName);
+ if (merged == null){
+ merged = localStats.clone();
+ }else {
+ merged.merge(localStats);
+ }
+ LOG.debug("Local Stats: " + accumulatorName);
+ LOG.debug(localStats.toString());
+ }
+ }
+
+ Assert.assertEquals(globalStats.cardinality,999);
+ Assert.assertEquals(globalStats.estimateCountDistinct(),100);
+ Assert.assertTrue(globalStats.getHeavyHitters().size()>0 &&
globalStats.getHeavyHitters().size()<=5);
+ Assert.assertEquals(merged.getMin(),globalStats.getMin());
+ Assert.assertEquals(merged.getMax(),globalStats.getMax());
+
Assert.assertEquals(merged.estimateCountDistinct(),globalStats.estimateCountDistinct());
+
Assert.assertEquals(merged.getHeavyHitters().size(),globalStats.getHeavyHitters().size());
+
+ }
+
+ public static class StringToInt extends RichFlatMapFunction<String,
Tuple1<Integer>> {
+
+ // Is instantiated later since the runtime context is not yet
initialized
+ private Accumulator<Object, Serializable> globalAccumulator;
+ private Accumulator<Object,Serializable>[] localAccumulators;
--- End diff --
I'm sorry, I think the comment was out of the context of the code above (my
bad).
I was proposing to expose events from the lifecycle of of an operator
(e.g., `Open(Operator)`, `Close(Operator)`). If these are created on points out
of the hot path during execution, the performance penalty should not be too
high. Add-on components can then react on the events with listeners.
In the statistics collection, we can have a listener that sets up the
accumulator when statistics tracking has been configured for an operator.
Couple this with a Scala trait in the add-ons package, and we can have a fluent
API that sets up statistics tracking:
```scala
// p is a projection function for tracking statistics
// alleviates the need to use RichMapFunction for f
val X = Y.map(f).withStatistics("Y-stats", k)
```
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