After reading the article on wiki -
I have several questions.

- Is it difference between multiple bolts with 1 parallelism hint and a
single bolt with multiple parallelism hint?
For example, if a developer program a topology by configuring 4 bolts,
which refers to the same class (or uses the same funciton), with 1
parallelism hint, is it the same as a topology configured with 1 bolt with
4 parallelism hint?

class X ... { ... }

builder.setBolts(..., new X())
builder.setBolts(..., new X())
builder.setBolts(..., new X())
builder.setBolts(..., new X())


builder.setBolts(..., new X(), 4)

- How are bolts allocated to workers?
I notice that when a topology is allocated, seemingly some of bolts are
allocated on the same worker whereas a few workers have not allocated with
any bolt for there is no execution found. Or how can I examine which bolt
is allocated to which worker?

- If the parallelism hint is configured for a bolt, would the thread
(launched corresponded to parallelism hint) read the same tuple value
emitted to that bolt?
For instance, a bolt A emits user names to a bolt B, configured parallelism
hint to 10; when A emits a user name like "Frodo Baggins", would 10 threads
read the same tuple value i.e. "Frodo Baggins" emitted from the bolt A? Or
one of threads receive "Frodo Baggins", while others may receive "Samwise
Gamgee" if the bolt A continuously emits other names?


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groupstorm-user @
postedDec 11, '12 at 8:17p
activeDec 11, '12 at 8:17p

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Jason lee: 1 post



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