I've seen many manifestations of ways to use the user class path as precedent to the hadoop one. Often times this is done if an m/r job needs a specific version of a library that hadoop coincidentally already uses an older version of (for example jackson's json parser or commons http , etc.)
In any case : I've seen :
mapreduce.task.classpath.user.precedence
mapreduce.task.classpath.first
mapreduce.job.user.classpath.first
Which one of these parameters is the right one to set in my job configuration, in order to force mappers and reducers to have a class path which puts my user defined hadoop_classpath jars BEFORE the hadoop default dependency jars ?
By the way, this is related to this question : Dynamodb requestHandler acception which I recently have found is due to a jar conflict.