Thanks for the response. I have the preferIPv4Stack option in hadoop-env.sh; however; this was not preventing the mapreduce container from enumerating the IPv6 address of the interface.
Jeff From: Chris Mawata [mailto:[email protected]] Sent: Sunday, December 15, 2013 3:58 PM To: [email protected] Subject: Re: Site-specific dfs.client.local.interfaces setting not respected for Yarn MR container You might have better luck with an alternative approach to avoid having IPV6 which is to add to your hadoop-env.sh HADOOP_OPTS="$HADOOP_OPTS -Djava.net.preferIPv4Stack=true Chris On 12/14/2013 11:38 PM, Jeff Stuckman wrote: Hello, I have set up a two-node Hadoop cluster on Ubuntu 12.04 running streaming jobs with Hadoop 2.2.0. I am having problems with running tasks on a NM which is on a different host than the RM, and I believe that this is happening because the NM host's dfs.client.local.interfaces property is not having any effect. I have two hosts set up as follows: Host A (1.2.3.4): NameNode DataNode ResourceManager Job History Server Host B (5.6.7.8): DataNode NodeManager On each host, hdfs-site.xml was edited to change dfs.client.local.interfaces from an interface name ("eth0") to the IPv4 address representing that host's interface ("1.2.3.4" or "5.6.7.8"). This is to prevent the HDFS client from randomly binding to the IPv6 side of the interface (it randomly swaps between the IP4 and IP6 addresses, due to the random bind IP selection in the DFS client) which was causing other problems. However, I am observing that the Yarn container on the NM appears to inherit the property from the copy of hdfs-site.xml on the RM, rather than reading it from the local configuration file. In other words, setting the dfs.client.local.interfaces property in Host A's configuration file causes the Yarn containers on Host B to use same value of the property. This causes the map task to fail, as the container cannot establish a TCP connection to the HDFS. However, on Host B, other commands that access the HDFS (such as "hadoop fs") do work, as they respect the local value of the property. To illustrate with an example, I start a streaming job from the command line on Host A: hadoop jar $HADOOP_HOME/share/hadoop/tools/lib/hadoop-streaming-2.2.0.jar -input hdfs://hosta/linesin/ -output hdfs://hosta/linesout -mapper /home/hadoop/toRecords.pl -reducer /bin/cat The NodeManager on Host B notes that there was an error starting the container: 13/12/14 19:38:45 WARN nodemanager.DefaultContainerExecutor: Exception from container-launch with container ID: container_1387067177654_0002_01_000001 and exit code: 1 org.apache.hadoop.util.Shell$ExitCodeException: at org.apache.hadoop.util.Shell.runCommand(Shell.java:464) at org.apache.hadoop.util.Shell.run(Shell.java:379) at org.apache.hadoop.util.Shell$ShellCommandExecutor.execute(Shell.java:589) at org.apache.hadoop.yarn.server.nodemanager.DefaultContainerExecutor.launchContainer(DefaultContainerExecutor.java:195) at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:283) at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:79) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) On Host B, I open userlogs/application_1387067177654_0002/container_1387067177654_0002_01_000001/syslog and find the following messages (note the DEBUG-level messages which I manually enabled for the DFS client): 2013-12-14 19:38:32,439 DEBUG [main] org.apache.hadoop.hdfs.DFSClient: Using local interfaces [1.2.3.4] with addresses [/1.2.3.4:0] <cut> 2013-12-14 19:38:33,085 DEBUG [main] org.apache.hadoop.hdfs.DFSClient: newInfo = LocatedBlocks{ fileLength=537 underConstruction=false blocks=[LocatedBlock{BP-1911846690-1.2.3.4-1386999495143:blk_1073742317_1493; getBlockSize()=537; corrupt=false; offset=0; locs=[5.6.7.8:50010, 1.2.3.4:50010]}] lastLocatedBlock=LocatedBlock{BP-1911846690-1.2.3.4-1386999495143:blk_1073742317_1493; getBlockSize()=537; corrupt=false; offset=0; locs=[5.6.7.8:50010, 1.2.3.4:50010]} isLastBlockComplete=true} 2013-12-14 19:38:33,088 DEBUG [main] org.apache.hadoop.hdfs.DFSClient: Connecting to datanode 5.6.7.8:50010 2013-12-14 19:38:33,090 DEBUG [main] org.apache.hadoop.hdfs.DFSClient: Using local interface /1.2.3.4:0 2013-12-14 19:38:33,095 WARN [main] org.apache.hadoop.hdfs.DFSClient: Failed to connect to /5.6.7.8:50010 for block, add to deadNodes and continue. java.net.BindException: Cannot assign requested address Note the failure to bind to 1.2.3.4, as the IP for Node B's local interface is actually 5.6.7.8. Note that when running other HDFS commands on Host B, Host B's setting for dfs.client.local.interfaces is respected. On host B: hadoop@nodeb:~$ hadoop fs -ls hdfs://hosta/ 13/12/14 19:45:10 DEBUG hdfs.DFSClient: Using local interfaces [5.6.7.8] with addresses [/5.6.7.8:0] Found 3 items drwxr-xr-x - hadoop supergroup 0 2013-12-14 00:40 hdfs://hosta/linesin drwxr-xr-x - hadoop supergroup 0 2013-12-14 02:01 hdfs://hosta/system drwx------ - hadoop supergroup 0 2013-12-14 10:31 hdfs://hosta/tmp If I change dfs.client.local.interfaces on Host A to eth0 (without touching the setting on Host B), the syslog mentioned above instead shows the following: 2013-12-14 22:32:19,686 DEBUG [main] org.apache.hadoop.hdfs.DFSClient: Using local interfaces [eth0] with addresses [/<some IP6 address>:0,/5.6.7.8:0] The job then successfully completes sometimes, but both Host A and Host B will then randomly alternate between the IP4 and IP6 side of their eth0 interfaces, which causes other issues. In other words, changing the dfs.client.local.interfaces setting on Host A to a named adapter caused the Yarn container on Host B to bind to an identically named adapter. Any ideas on how I can reconfigure the cluster so every container will try to bind to its own interface? I successfully worked around this issue by doing a custom build of HDFS which hardcodes my IP address in the DFSClient, but I am looking for a better long-term solution. Thanks, Jeff
