I am using TridentTopology to read from a file and emit aggregates using a single spout. When I have a single supervisor node, the topology is working fine and spout is emitting fine. However when a second supervisor node is added, the spout stops emitting. I was able to verify that there are two supervisor nodes using Storm UI. There are no errors either in supervisor log or worker log files on both the nodes.
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I have a bolt to process the data in filedGrouping way from a spout in storm . And one day one machine was down, the bolt was transfered to another machine automatically. In filedGrouping way , some tuples from the spout will not be processed by any bolt . How can I do with it?
If you use acking, the tuples that are lost should be retried by the spout.
I ran a storm topology on a storm cluster. Later the topology was killed. But it is not getting removed from the list of topologies. Hence I can't rerun the topology with the same name again.
Isn't there a way to remove the killed topology from the list ?
When you kill the topology you normally set a timeout for how long you want to wait for currently emitted tuples to be processed. I think the default is 30 seconds. After that the topology should be removed from the list. If you don't want to wait, you can just specify a timeout of 0 seconds, and the topology will be removed immediately.
When you run kill command from storm ui or command line .Storm will first deactivate the topology's spouts for the duration of the topology's message timeout to allow all messages currently being processed to finish processing. Storm will then shutdown the workers and clean up their state .
So, maybe your topology still has message that needs to be processed .Hence the topology has not died till now .
Yet another way to kill topology is run storm kill from the command line. This had worked for me when one topology hung in "KILLED" state and shown in the list for hours.
storm kill yourToplogyName -w 5
We have an use case where we do not want to run storm topology continuously. Instead, there are set of inputs( 10K+) that should be processed at the specified time, Spout continuously emits these inputs and get processed by rest of the bolts in the topology. Once all the inputs are processed, there is nothing to emit from nextTuple in my spout.
At this time we wanted our topology to go to sleep and restart the process everyday night 12:00 am.
Is there any property to set in the storm config to run the topology once a day and sleep after processing is done and start at the specified time?
I'm not aware of a feature like what you're asking for. Storm isn't a batch processing system, it's meant to be running continuously. Consider if Storm is a great fit for this use case.
That said, you should be able to implement what you want. You could put in an "I'm done" message at the end of your spout input. When the spout hits that message and all other pending messages are acked, it could use the Nimbus client to kill or deactivate the topology (depending on whether you want to kill or deactivate), see https://stackoverflow.com/a/37134473/8845188. Then the final step would be using your favorite scheduling software to resubmit/reactivate the topology every day at midnight.
Say I deploy a topology with 2 workers, the topo has 1 spout and 1 bolt with 2 tasks. Then my understanding is, 1 worker will run spout executor and 1 bolt executor, the other worker will run 1 bolt executor.
Is my understanding correct?
If my understanding is correct, then my question comes. Say the bolt is implemented by Python. Since storm transfers data between multi-lang bolts via stdout/stdin, if the 2 workers run on different hosts, how spout can send data to bolt that locates on the other host?
Little more clarification to your question. Storm uses various types of queue for data/tuple transfer between various components of topology
Example :
1) Intra-worker communication in Storm (inter-thread on the same Storm node): LMAX Disruptor
2) Inter-worker communication (node-to-node across the network): ZeroMQ or Netty
3) Inter-topology communication: nothing built into Storm, you must take care of this yourself with e.g. a messaging system such as Kafka/RabbitMQ, a database, etc.
For further reference :
http://www.michael-noll.com/blog/2013/06/21/understanding-storm-internal-message-buffers/
To give a more detailed answer:
Storm will sent the data to both bolt executors. For the spout-local bolt, this happens in-memory; for the other bolt via network. Afterwards, each bolt-instance will deliver the input to an local-running python process. Thus, your describe stdout/stdin delivery happens locally on each machine. The data is transfer to each bolt before the data delivery from Java to Python happens.
Thus, stdout/stdin bridge is used within each bolt, and not from spout to bolt.
I have done a test by myself. Storm can properly deliver spout emitted data to bolts on different hosts.
Right now Storm Spouts have an open method to configure them and Bolts have a prepare method. Is there any way to make all the Spout instances wait for all the prepare methods on the Bolts listening to them to finish?
I have a case where I would like to pass some config info to the bolts on the fly (since this config info changes all the time). I've read in some places that we should use Zookeeper or an in-memory key-value storage like redis to do this. My worry though is, what happens if the Bolts aren't ready to process data from Spouts yet, and the Spouts start emitting tuples? Is there a way to make the Spouts wait for an update from the Bolts saying they're ready?
I found a slightly more elegant solution for this (I think). The problem was that certain bolts needed config info in order to process incoming tuples. I figured out Storm's capability to replay tuples, so now my bolts listen for updates from one spout, and tuples from the other. As long as I dont receive updates, I keep failing the tuples and having the spout replay them after a configurable amount of time.
Yes, you can use Redis to store your configuration then read it from the prepare method.
The prepare method is invoked by the worker process which start processing tuples after finishing. Actually, I think that no tuple is emitted until all components of a worker process are ready. http://nathanmarz.github.io/storm/doc-0.8.1/index.html
Finally, you can have an additional spout which look up for configuration changes. Then, if a newer configuration is available it is send to your bolts via named streams.
You don't have to worry about this. Storm framework loads Bolt before Spout. Storm loads the bolts in reverse order. Bolts towards the end of the topology are loaded before the bolts in the middle of the topology and in the end, Spout gets loaded.