prateekm opened a new pull request #1241: SAMZA-2424: AM should cache and serve 
serialized Job Model to containers
URL: https://github.com/apache/samza/pull/1241
 
 
   Symptom: AM runs out of memory or gets stuck in GC loop during job 
deployment.
    
   Cause: During startup, containers fetch the JobModel and configs from the 
job coordinator http endpoint. For jobs with a large number of containers this 
can mean many concurrent requests to the JC Servlet for the large job model. 
The servlet currently serializes the JobModel to JSON for every incoming 
request. This can lead to excessive memory utilization and GC, leading to slow 
response times, AM running out of memory, or AM getting stuck in GC loop.
    
   Changes: JobModelManager now serializes the JobModel when creating the 
JobServlet. JobServlet now serves this serialized JobModel instead of 
serializing every time.
    
   Tests: Local performance test results using ab and monitoring memory 
utilization using YourKit: 
https://docs.google.com/document/d/1Qy4ScC9aLNZaJQuUBvtyoXdilUhkVtYjb5Mzwzv-DV8/edit?usp=sharing
   
   API Changes: None
    
   Upgrade Instructions: None
    
   Usage Instructions: None

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