Just ran into this problem running mahout from CDH4 in standalone mode in my MacBook Air. The issue is that a /tmp/hadoop-xxx/xxx/LICENSE file and a /tmp/hadoop-xxx/xxx/license directory are being created on a case-insensitive file system when unjarring the mahout jobs. I was able to workaround this by deleting META-INF/LICENSE from the jar file like this: … Read more
Two things worked for me, STEP 1 : stop hadoop and clean temp files from hduser sudo rm -R /tmp/* also, you may need to delete and recreate /app/hadoop/tmp (mostly when I change hadoop version from 2.2.0 to 2.7.0) sudo rm -r /app/hadoop/tmp sudo mkdir -p /app/hadoop/tmp sudo chown hduser:hadoop /app/hadoop/tmp sudo chmod 750 /app/hadoop/tmp … Read more
It is possible to create many tables (both managed and external at the same time) on top of the same location in HDFS. Creating tables with exactly the same schema on top of the same data is not useful at all, but you can create different tables with different number of columns for example or … Read more
You want xreadlines, it reads lines from a file without loading the whole file into memory. Edit: Now I see your question, you just need to get the stdout pipe from your Popen object: cat = subprocess.Popen([“hadoop”, “fs”, “-cat”, “/path/to/myfile”], stdout=subprocess.PIPE) for line in cat.stdout: print line
You can use hdfs fsck / to determine which files are having problems. Look through the output for missing or corrupt blocks (ignore under-replicated blocks for now). This command is really verbose especially on a large HDFS filesystem so I normally get down to the meaningful output with hdfs fsck / | egrep -v ‘^\.+$’ … Read more
You can use the sliding function from MLLIB which probably does the same thing as Daniel’s answer. You will have to sort the data by time before using the sliding function. import org.apache.spark.mllib.rdd.RDDFunctions._ sc.parallelize(1 to 100, 10) .sliding(3) .map(curSlice => (curSlice.sum / curSlice.size)) .collect()
In order to forcefully let the namenode leave safemode, following command should be executed: bin/hadoop dfsadmin -safemode leave You are getting Unknown command error for your command as -safemode isn’t a sub-command for hadoop fs, but it is of hadoop dfsadmin. Also after the above command, I would suggest you to once run hadoop fsck … Read more
First of all shuffling is the process of transfering data from the mappers to the reducers, so I think it is obvious that it is necessary for the reducers, since otherwise, they wouldn’t be able to have any input (or input from every mapper). Shuffling can start even before the map phase has finished, to … Read more
From Apache docs The ZKFailoverController (ZKFC) is a new component which is a ZooKeeper client which also monitors and manages the state of the NameNode. Each of the machines which runs a NameNode also runs a ZKFC, and that ZKFC is responsible for: Health monitoring – the ZKFC pings its local NameNode on a periodic … Read more
an alternative to @Tariq’s asnwer you could pass the URI when getting the filesystem import org.apache.hadoop.fs.FileSystem import org.apache.hadoop.conf.Configuration import java.net.URI import org.apache.hadoop.fs.Path import org.apache.hadoop.util.Progressable import java.io.BufferedWriter import java.io.OutputStreamWriter Configuration configuration = new Configuration(); FileSystem hdfs = FileSystem.get( new URI( “hdfs://localhost:54310” ), configuration ); Path file = new Path(“hdfs://localhost:54310/s2013/batch/table.html”); if ( hdfs.exists( file )) { hdfs.delete( … Read more