Github user nickwallen commented on a diff in the pull request:

    https://github.com/apache/metron/pull/984#discussion_r180154515
  
    --- Diff: 
metron-deployment/packaging/ambari/metron-mpack/src/main/resources/common-services/METRON/CURRENT/configuration/metron-enrichment-env.xml
 ---
    @@ -129,70 +145,156 @@
       <property>
         <name>enrichment_topology_max_spout_pending</name>
         <description>Spout Max Pending Tuples for the Enrichment 
Topology</description>
    -    <value/>
    -    <display-name>Enrichment Max Pending</display-name>
    +    <value>500</value>
    --- End diff --
    
    This is about tuning the user's day 1 experience.  Specifically what I have 
seen is on day 1 users push some telemetry into a topic, start up the topology, 
and the topology just blows-up.  They have no idea why because they are on day 
1.   That is a bad experience.
    
    The topology blows-up because on day 1 the user is running with a topology 
that has NOT been tuned.  The topology blows-up because when this value is 
undefined there is no back pressure.  We need some back pressure here to avoid 
the day 1 blow-up.
    
    I'd prefer a day 1 user be able to start up the topology and see it 
actually work, albeit slowly, under most conditions.  A user running against 
heavier load is more likely to be experienced and should have more knowledge to 
know that this value needs increased.
    
    



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