Map reduce job getting stuck at map 0% reduce 0%

Question

I am running the famous wordcount example. I have a local and prod hadoop setup. The same example is working in prod, but its not working locally. Can someone tell me what should I look for. The job is getting stuck. The task logs are:

~/tmp$ hadoop jar wordcount.jar WordCount /testhistory /outputtest/test
Warning: $HADOOP_HOME is deprecated.

13/08/29 16:12:34 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
13/08/29 16:12:35 INFO input.FileInputFormat: Total input paths to process : 3
13/08/29 16:12:35 INFO util.NativeCodeLoader: Loaded the native-hadoop library
13/08/29 16:12:35 WARN snappy.LoadSnappy: Snappy native library not loaded
13/08/29 16:12:35 INFO mapred.JobClient: Running job: job_201308291153_0015
13/08/29 16:12:36 INFO mapred.JobClient:  map 0% reduce 0%

Locally hadoop in running as pseudo distributed mode. All the 3 processes, namenode, datanode, jobtracker is running. Let me know if some extra information is required.

Avina

Anything interesting in JT/TT logs? – Butt

JobTracker logs: http://pastebin.com/jY1CAQaA I don't see any issues in the log file. – Avina

Thank you for providing the info. What about h/w?Is it same as the prod cluster?Try to monitor and see if there is some h/w related issue, most probably RAM. – Butt

There is hardware differences. But I am not able to think, why this can be an issue. This simple task is running for a very small file (2-3 KBs) which is way too smaller than available RAM. – Avina

Oh..absolutely. One more thing, you have written that NN, DN and JT are running fine. What about the TT? – Butt

There is not tasktracker running. I don't have any details about this, as I have just started learning hadoop. I am googling it for more details. But suggestions and details regarding tasktracker, from you, will be welcomed. – Avina

You must have a running TT. TT is the daemon that is actually going to run your mappers and reducers. Without it, you can't go ahead. Please make sure it is running fine. Or show me the TT logs. – Butt

Awesome, it worked. I started the tasktracker and everything worked. Thanks :). If you want you can post it as a solution, and I will accept it. – Avina

Answer 1

The tasktracker seems to be missing.

Try:

hadoop tasktracker &

Prefabricate

Answer 2

In Hadoop 2.x this problem could be related to memory issues, you can see it in MapReduce in Hadoop 2.2.0 not working

Brassard

Answer 3

I had the same problem and this page helped me: http://www.alexjf.net/blog/distributed-systems/hadoop-yarn-installation-definitive-guide/

Basically I solved my problem using the following 3 steps. The fact is that I had to configure much more memory I really have.

1) yarn-site.xml

• yarn.resourcemanager.hostname = hostname_of_the_master
• yarn.nodemanager.resource.memory-mb = 4000
• yarn.nodemanager.resource.cpu-vcores = 2
• yarn.scheduler.minimum-allocation-mb = 4000

2) mapred-site.xml

• yarn.app.mapreduce.am.resource.mb = 4000
• yarn.app.mapreduce.am.command-opts = -Xmx3768m
• mapreduce.map.cpu.vcores = 2
• mapreduce.reduce.cpu.vcores = 2

3) Send these files across all nodes

Priestcraft

for the step 3: how can I do that? – Florez

simply copy the files from one node to the others using the "scp" command – Priestcraft

Answer 4

Except for hadoop tasktracker & and any other issues. Please check you code and make sure that there is no infinite loop or any other bugs. Maybe there are some bugs in your code!

Campobello

Answer 5

If this problem is coming when using Hive queries then do check if you are joining two very big tables without leveraging partitions. Not using partitions may lead to long running full table scans and hence stuck at map 0% reduce 0%.

Japha

How can I track the status? – Cranny

see the question and log provided there you will find the line. 13/08/29 16:12:36 INFO mapred.JobClient: map 0% reduce 0% – Japha