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ProgrammingGuideTaskSetVariable  
SSS Mapreduce Programming Guide - TaskSet variable
ja , en
Updated Feb 27, 2013

TaskSet variable

In SSS Mapreduce, Mappers/Reducers created by same JobEngine can share any objects in remote site. This function is called "TaskSet variable".

In TaskSet variable, Context#setTaskSetVariable is available to set any object using string as key.

void setTaskSetVariable(java.lang.String key, java.lang.Object v)

Context#getTaskSetVariable is available to get the object from the specified key.

<T> T getTaskSetVariable(java.lang.String key, java.lang.Class<T> klass)

We assume the following usage.

  1. "configure" method of the job invoked first reads tuples by Context#scanSideData etc.
  2. The jobs invoked by same JobEngine refers the read tuples.

WARNING:

Mappers/Reducers can share any object using TaskSet variable, but can share in only same worker server. Mappers/Reducers cannot share any object between worker servers.

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