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From "Ana M. Martinez" <...@cs.aau.dk>
Subject Re: Problem to show logs in task managers
Date Mon, 04 Jan 2016 11:36:16 GMT
Hi Till,

Sorry for the delay (Xmas break). I have activated log aggregation on flink-conf.yaml with
yarn.log-aggregation-enable: true (as I can’t find a yarn-site.xml).
But the command yarn logs -applicationId application_1451903796996_0008 gives me the following

INFO client.RMProxy: Connecting to ResourceManager at xxx
/var/log/hadoop-yarn/apps/hadoop/logs/application_1451903796996_0008does not exist.
Log aggregation has not completed or is not enabled

I’ve tried to restart the Flink JobManager and TaskManagers as follows:
./bin/yarn-session.sh -n 1 -tm 2048 -s 4
and then with a detached screen, run my application with ./bin/flink run -m yarn-cluster ...

I am not sure if my problem is that I am not setting the log-aggregation-enable property well
or I am not restarting the Flink JobManager and TaskManagers as I should… Any idea?


On 18 Dec 2015, at 16:29, Till Rohrmann <trohrmann@apache.org<mailto:trohrmann@apache.org>>

In which log file are you exactly looking for the logging statements? And on what machine?
You have to look on the machines on which the yarn container were started. Alternatively if
you have log aggregation activated, then you can simply retrieve the log files via yarn logs.


On Fri, Dec 18, 2015 at 3:49 PM, Ana M. Martinez <ana@cs.aau.dk<mailto:ana@cs.aau.dk>>
Hi Till,

Many thanks for your quick response.

I have modified the WordCountExample to re-reproduce my problem in a simple example.

I run the code below with the following command:
./bin/flink run -m yarn-cluster -yn 1 -ys 4 -yjm 1024 -ytm 1024 -c mypackage.WordCountExample

And if I check the log file I see all logger messages except the one in the flatMap function
of the inner LineSplitter class, which is actually the one I am most interested in.

Is that an expected behaviour?


import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.Collector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

public class WordCountExample {
    static Logger logger = LoggerFactory.getLogger(WordCountExample.class);

    public static void main(String[] args) throws Exception {
        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        logger.info("Entering application.");

    DataSet<String> text = env.fromElements(
                "Who's there?",
                "I think I hear them. Stand, ho! Who's there?");

        List<Integer> elements = new ArrayList<Integer>();

        DataSet<TestClass> set = env.fromElements(new TestClass(elements));

        DataSet<Tuple2<String, Integer>> wordCounts = text
                .flatMap(new LineSplitter())
                .withBroadcastSet(set, "set")



    public static class LineSplitter implements FlatMapFunction<String, Tuple2<String,
Integer>> {

        static Logger loggerLineSplitter = LoggerFactory.getLogger(LineSplitter.class);

        public void flatMap(String line, Collector<Tuple2<String, Integer>> out)
            loggerLineSplitter.info("Logger in LineSplitter.flatMap");
            for (String word : line.split(" ")) {
                out.collect(new Tuple2<String, Integer>(word, 1));

    public static class TestClass implements Serializable {
        private static final long serialVersionUID = -2932037991574118651L;

        static Logger loggerTestClass = LoggerFactory.getLogger("WordCountExample.TestClass");

        List<Integer> integerList;
        public TestClass(List<Integer> integerList){
            loggerTestClass.info("Logger in TestClass");


On 17 Dec 2015, at 16:08, Till Rohrmann <trohrmann@apache.org<mailto:trohrmann@apache.org>>

Hi Ana,

you can simply modify the `log4j.properties` file in the `conf` directory. It should be automatically
included in the Yarn application.

Concerning your logging problem, it might be that you have set the logging level too high.
Could you share the code with us?


On Thu, Dec 17, 2015 at 1:56 PM, Ana M. Martinez <ana@cs.aau.dk<mailto:ana@cs.aau.dk>>
Hi flink community,

I am trying to show log messages using log4j.
It works fine overall except for the messages I want to show in an inner class that implements
I am very new to this, but it seems that I’m having problems to show the messages included
in the isConverged function, as it runs in the task managers?
E.g. the log messages in the outer class (before map-reduce operations) are properly shown.

I am also interested in providing my own log4j.properties file. I am using the ./bin/flink
run -m yarn-cluster on Amazon clusters.


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