We got NoClassDefFoundError and ExceptionInitializerError in prepare() methods.
On Mon, Jul 15, 2019 at 4:13 PM Petr Janeček <[email protected]> wrote: > Hello, > you'll need to define "fallen apart". What did not work and why? Obviously > a singleton is single in one Worker (one JVM). For DB connections, this > seems to be a good thing - you'll want every JVM to have a single (or, > rather, a limited pool of) DB connection encapsulated in a singleton > resource. > > If you want a singleton to really be single in the topology, you'll need > to abstract away the DB connection logic to a separate microservice, or a > single bolt. > > PJ > > ---------- Původní e-mail ---------- > Od: Denis Sevosteenko <[email protected]> > Komu: [email protected] > Datum: 15. 7. 2019 15:08:26 > Předmět: Storm and singletons > > Hi all, > > This may be an old question, but what is the correct way of using > Singleton pattern with Storm? > > Currently we have a topology with around 200 bolts, of which around 50 > read and write data from/to Cassandra. Each of these 50 bolts creates a new > Cassandra session, which to my understanding of Cassandra is not great. We > have tried solving this issue with several implementations of singletons: > lazy static, eager static and enum. All of these implementations have > worked in dev environment running on single server, but have fallen apart > on QA environment which has two supervisor hosts. I'm new to Storm so I > have no idea if we are missing something crucial or obvious. > > Thanks & Regards, > Denis Sevosteenko > >
