I'm not sure there are risks specifically. The best practice is to use Cloudera manager to configure memory limits for different services, so this is the right way to configure things.   Cloudera Manager does have support to help set up memory limits for applications: https://www.cloudera.com/documentation/enterprise/latest/topics/cm_mc_autoconfig.html#concept_xjy_vb3_rn .    For a production system, it's important to put thought into how much memory your system needs and how it's allocated between different services.  E.g. as an earlier poster saw, 256MB is not enough memory to do much interesting with Impala.     ... View more