ExclamationTopology workers executors vs tasks

[patcharee]

Hi,

I am new to Storm. I am running the storm starter example 
ExclamationTopology on storm cluster (version 0.10). The code snippet is 
below:

TopologyBuilder builder =new TopologyBuilder();

builder.setSpout("word",new TestWordSpout(),10);
builder.setBolt("exclaim1",new ExclamationBolt(),3).shuffleGrouping("word");
builder.setBolt("exclaim2",new ExclamationBolt(),2).shuffleGrouping("exclaim1");


However I do not understand why the Num executors and Num tasks of this 
topology (seen from the Storm UI) are both 18 (instead of 15) ? Also 
from the Storm UI, the Num executors and Num tasks of the Spout word and 
the Bolt exclaim1 and exclaim2 are 10, 3 and 2 respectively (as same as 
defined in the code).

Thanks,
Patcharee