Driver OOM after upgrading to 1.5

[Sandy Ryza]

I just upgraded the spark-timeseries
<https://github.com/cloudera/spark-timeseries> project to run on top of
1.5, and I'm noticing that tests are failing with OOMEs.

I ran a jmap -histo on the process and discovered the top heap items to be:
   1:        163428       22236064  <methodKlass>
   2:        163428       21112648  <constMethodKlass>
   3:         12638       14459192  <constantPoolKlass>
   4:         12638       13455904  <instanceKlassKlass>
   5:         10539        7642528  <constantPoolCacheKlass>

Not sure whether this is suspicious.  Any ideas?

-Sandy