[GitHub] bwmcadams opened a new pull request #3515: Introduce separate Akka dispatchers for CouchDB and Kafka Clients (#2954)

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bwmcadams opened a new pull request #3515: Introduce separate Akka dispatchers for CouchDB and Kafka Clients (#2954)
URL: https://github.com/apache/incubator-openwhisk/pull/3515
 
 
   - Rest of system continues to use the default system dispatcher
   
   
   Refs #2954
   
   
   <!--- Provide a concise summary of your changes in the Title -->
   
   ## Description
   
   This reopens the previous  #2956 PR; fork-join-executor wasn't the right choice previously and it is using Thread Pool dispatchers now, which are the correct way to handle this kind of IO separation with Akka. Defaults are set to what should be a reasonable starting point, especially given that couch and kafka now have their own separate execution pools from the "Default"/main system.
   
   <!--- Provide a detailed description of your changes. -->
   
    Kafka and CouchDB clients each get their own dispatchers
     * This should prevent all of the akka based stuff from competing constantly for threads
     * Kafka and Couch can be tuned now based on individual needs
     * Using thread-pool dispatchers, which are best suited for these processes (default is fork-join)
   - Dispatchers are defined in common `reference.conf`, so config can be overridden by dependents
   
   <!--- Include details of what problem you are solving and how your changes are tested. -->
   
   Currently, OpenWhisk is sharing a single fork-join-executor across the board for the entire `ActorSystem`, which is less than ideal especially when dealing with potentially blocking IO. 
   
   ## Related issue and scope
   <!--- Please include a link to a related issue if there is one. -->
   - [x] I opened an issue to propose and discuss this change (#2954 )
   
   ## My changes affect the following components
   <!--- Select below all system components are affected by your change. -->
   <!--- Enter an `x` in all applicable boxes. -->
   - [ ] API
   - [ ] Controller
   - [ ] Message Bus (e.g., Kafka)
   - [ ] Loadbalancer
   - [ ] Invoker
   - [ ] Intrinsic actions (e.g., sequences, conductors)
   - [ ] Data stores (e.g., CouchDB)
   - [ ] Tests
   - [ ] Deployment
   - [ ] CLI
   - [ ] General tooling
   - [ ] Documentation
   
   ## Types of changes
   <!--- What types of changes does your code introduce? Use `x` in all the boxes that apply: -->
   - [ ] Bug fix (generally a non-breaking change which closes an issue).
   - [ ] Enhancement or new feature (adds new functionality).
   - [ ] Breaking change (a bug fix or enhancement which changes existing behavior).
   
   ## Checklist:
   <!--- Please review the points below which help you make sure you've covered all aspects of the change you're making. -->
   
   - [x] I signed an [Apache CLA](https://github.com/apache/incubator-openwhisk/blob/master/CONTRIBUTING.md).
   - [x] I reviewed the [style guides](https://github.com/apache/incubator-openwhisk/wiki/Contributing:-Git-guidelines#code-readiness) and followed the recommendations (Travis CI will check :).
   - [ ] I added tests to cover my changes. (not easily testable in unit/integration)
   - [ ] My changes require further changes to the documentation.
   - [ ] I updated the documentation where necessary.
   
   

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