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References
CPS-2146: Analysis of Out of Memory and related Errors in NCMP
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<Note. use green for closed issues, yellow for important ones if needed>
Background
The use of Hazelcast during NCMP's CM-handle Module Sync is leading to:
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Module Set Syncing
Proof of Concept
A PoC was is being constructed: WIP Remove hazelcast map for module sync | https://gerrit.nordix.org/c/onap/cps/+/20724
From the PoC, it was determined that when running multiple instances of NCMP, there was approximately 10% of batches being processed by both instances simultaneously, which led to some handles going to LOCKED state, due to database exceptions. Two solutions proposed:
- Add a distributed lock (from Hazelcast) to create a critical section, allowing only 1 instance to to move handles to SYNCING state
- Allow collisions, by gracefully handling AlreadyDefinedExceptions in the code
Solution 1 is verified to work, and gives 50% faster registration than now. Solution 2 is not yet tested, so it is yet to be determined which has better performance/reliability.