[ https://issues.apache.org/jira/browse/MAPREDUCE-6803?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Wangda Tan updated MAPREDUCE-6803: ---------------------------------- Labels: oct16-medium (was: oct16-hard) > YARN shoud allocate container that is closest to the data > --------------------------------------------------------- > > Key: MAPREDUCE-6803 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-6803 > Project: Hadoop Map/Reduce > Issue Type: Improvement > Components: applicationmaster > Environment: Hadoop cluster with multi-level network hierarchy > Reporter: jaehoon ko > Labels: oct16-medium > Attachments: YARN-3856.001.patch, YARN-3856.002.patch > > > Currently, given a Container request for a host, ResourceManager allocates a > Container with following priorities (RMContainerAllocator.java): > - Requested host > - a host in the same rack as the requested host > - any host > This can lead to a sub-optimal allocation if Hadoop cluster is deployed on > multi-level networked hosts (which is typical). For example, let's suppose a > network architecture with one core switches, two aggregate switches, four ToR > switches, and 8 hosts. Each switch has two downlinks. Rack IDs of hosts are > as follows: > h1, h2: /c/a1/t1 > h3, h4: /c/a1/t2 > h5, h6: /c/a2/t3 > h7, h8: /c/a2/t4 > To allocate a container for data in h1, Hadoop first tries h1 itself, then > h2, then any of h3 ~ h8. Clearly, h3 or h4 are better than h5~h8 in terms of > network distance and bandwidth. However, current implementation choose one > from h3~h8 with equal probabilities. > This limitation is more obvious when considering hadoop clusters deployed on > VM or containers. In this case, only the VMs or containers running in the > same physical host are considered rack local, and actual rack-local hosts are > chosen with same probabilities as far hosts. > The root cause of this limitation is that RMContainerAllocator.java performs > exact matching on rack id to find a rack local host. Alternatively, we can > perform longest-prefix matching to find a closest host. Using the same > network architecture as above, with longest-prefix matching, hosts are > selected with the following priorities: > h1 > h2 > h3 or h4 > h5 or h6 or h7 or h8 -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: mapreduce-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: mapreduce-issues-h...@hadoop.apache.org