the spark job is so slow - almost frozen

[Zhiliang Zhu]

Hi All,  
Here we have one application, it needs to extract different columns from 6 hive 
tables, and then does some easy calculation, there is around 100,000 number of 
rows in each table,finally need to output another table or file (with format of 
consistent columns) .
 However, after lots of days trying, the spark hive job is unthinkably slow - 
sometimes almost frozen. There is 5 nodes for spark cluster.  Could anyone 
offer some help, some idea or clue is also good. 
Thanks in advance~
Zhiliang