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From Edward Zhang <>
Subject [Discussion] storm local-mode event object reuse bug
Date Tue, 01 Dec 2015 04:46:26 GMT
Hi Storm developers,

Today, I hit one possible storm issue which happens in local mode. In local
mode, one event object is sent out of spout and looks it does not go
through serialization/deserialization, instead this event object including
its members is directly referenced by following bolts. So when one bolt
modifies this event object then another bolt will also see the changes

For example the event object sent by spout includes one java Map object, if
there are 2 following bolts after this spout, then in one bolt if we modify
this Map object, then the other bolt will see that or throw
concurrentmodificationexception if it iterates the Map Object.

Please let us know if this behavior should be corrected by storm framework
or by storm application. In storm application, we can do deep copy if it's
local mode, but in storm framework, probably serialization/deserialization
should be always executed.

Let me know your thoughts.

Edward Zhang

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