title: Tez. Slow reducers
body: <p>I have strange behavior with TEZ mapreduce job.</p>
  
  <p>I'm trying to read logs data from Hive, split it into some chunks by id, date and some other parameters and then write to another hive tables. </p>
  
  <p>Map phase works fast enough and takes about 20 minutes, than reducers start to work and 453 from 458 reducers process all data within next 20 minutes. But last 5 reducers work for about 1 hour. </p>
  
  <p>It happens because my input data includes some huge entries and processing these entries takes a lot of time.
  What is the best practice for such cases? Should I make some hadoop/tez/hive tuning to allow kind of parallel processing for last reducers or it would be smarter to split input data by other parameters to avoid huge entries?</p>
  
  <p>Thanks for any advice.</p>