Hi Taylor, Thank you very much for the information. You cleared all my doubts.
Regards, Thilina On Tue, Jul 7, 2015 at 9:19 PM, P. Taylor Goetz <[email protected]> wrote: > Hi Thilina, > > 1. With Storm’s Core API (spouts/bolts) if you are storing state in an > in-memory structure such as a HashMap, that state will be lost in the event > of a worker crash. It is up to you to provide the logic for persisting > state and restoring it in the event of a failure; Storm will not do it for > you. Storm’s trident API on the other hand has an abstraction for > persistent state [1] and there are implementations for various backing > stores like HBase, Redis, and others. In the storm-hbase module there is an > example of a persistent word count. > > 2. Storm uses zookeeper for things like nimbus assignments and > worker/supervisor heartbeats. The Trident API also uses zookeeper for > tracking transactions. Other components may use zookeeper as well. The > kafka spout, for example, uses zookeeper for tracking offsets. > > -Taylor > > > [1] https://storm.apache.org/documentation/Trident-state.html > > > > On Jul 7, 2015, at 2:16 AM, Thilina Rathnayake <[email protected]> > wrote: > > > > Hi All, > > > > I am a newbie to storm and have a few questions regarding the state in > storm. I will be > > really grateful if someone can help me out with the following. > > > > * Consider the word count topology in `storm-starter`. We have a map > called `counts` > > in it. Does storm store `count` in zookeeper or anywhere else so that > if the worker > > dies we are able to recover the data inside `counts`? > > > > * What state information of supervisors/workers are stored in the > zookeeper? > > > > Thanks in advance ! > > > > Regards, > > Thilina > >
