can we use log4j in mapreduce?

Question

Can we use log4j to log in mapreduce? If so, provide the steps to use log4j in map-reduce to log the information. I have written the below log4.properties but, nothing was logged.

Answer 1

Here is one simple way to configure the Log4j in Mapper, just for

Standard practices for logging in MapReduce jobs

and the code snippet goes here

import org.apache.log4j.Logger; // other imports omitted

public class SampleMapper extends Mapper { private Logger logger = Logger.getLogger(SampleMapper.class);

@Override
protected void setup(Context context) {
    logger.info("Initializing NoSQL Connection.")
    try {
        // logic for connecting to NoSQL - ommitted
    } catch (Exception ex) {
        logger.error(ex.getMessage());
    }
}

@Override
protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
    // mapper code ommitted
}

}

Sorry for formatting.