Database Reference
In-Depth Information
The Storm UI
First of all, let's understand which statistics and indicators are present on the UI itself. The
latest UI has scores of indicators that give us an insight into what is going on in the cluster
and what could go wrong (just in case things break).
Let's look at Storm UI where the Cluster Summary entails, for example, http:// ip
of nimbus:8080 in my case is http://10.4.2.122:8080 and my UI process ex-
ecutes on the nimbus machine that has this IP: 10.4.2.122.
In the preceding screenshot, we can see the following parameters:
• The version of Storm being used is in the first column.
• The uptime of Nimbus (second column) tells us how long the Nimbus node has
been running since the last restart. Nimbus, as we know, is required only at the
time when the topology is submitted or when a supervisor or worker has gone
down and the tasks are being delegated again. Nimbus is also required to be up
during the rebalancing of the topology.
• The third column gives us the number of supervisors on the cluster.
• Columns four, five, and six show the number of used worker slots, number of free
worker slots, and total number of worker slots across the Storm supervisors. This is
a very important statistic. In any production grade cluster, one should always have
a provision for some of the workers going down or one or two supervisors being
killed. So, I recommend that you always have enough free slots on your cluster to
accommodate such sudden failures.
• Column seven and column eight specify the moving tasks in the topology, that is,
in terms of the number of tasks and executors running in the system.
Let's have a look at the second section on the Storm UI opening page; this one captures the
topology summary:
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