Database Reference
In-Depth Information
Understanding the jobtracker UI
The jobtracker user interface provides useful information related to the jobs executed on
the cluster. The jobtracker status can be monitored via the following jobtracker URL:
http://<serveraddress>:50030/
The UI provides complete information of the status of the jobtracker along with the pro-
gress information of the task. The jobtracker page is divided into the following sections:
•
General Information
: The general information section displays some basic in-
formation of the jobtracker such as the current status, the timestamp of when the
service was started, the compilation information, and a unique identifier for the
service.
The following screenshot shows the
General Information
section of the jobtrack-
er web interface:
•
Cluster Summary
: This section displays information about the tasks and nodes
available in the cluster. Information such as the current running map and reduce
tasks and number of nodes in the cluster are self-explanatory. Every tasktracker in
the cluster has a configured number of map and reduce slots. The occupied map
slots shows the number of map slots currently in use out of the total number of
slots available in the cluster. Similarly, the occupied reduce slots show the number
of reduce slots currently in use out the total available. The map task capacity and
reduce task capacity is the value that represents the maximum number of map tasks
and reduce tasks that can be run on the cluster. The average tasks per node shows
the average number of map or reduces tasks that run on the cluster.
If a node is not performing correctly, the jobtracker can blacklist the node so that
no new tasks are assigned to it. The
Blacklisted Nodes
column in the
Cluster
