[GitHub] cbickel opened a new pull request #3971: Bump fetch.max.wait of Kafka-consumers to lower the load on Kafka in large systems.

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cbickel opened a new pull request #3971: Bump fetch.max.wait of Kafka-consumers to lower the load on Kafka in large systems.
URL: https://github.com/apache/incubator-openwhisk/pull/3971
 
 
   ## Description
   
   In systems with a lot of invokers, all Kafka-consumers are slowing down Kafka if they are ideling.
   
   I did some tests with the fetch.max.wait.ms-parameter.
   I produce messages to one topic. Each consumer has it’s own topic. So if there are 100 consumers, 99 of them are idling.
   I used the command kafka-producer-perf-test.sh --topic invoker0 --num-records 100000 --throughput 999999999 --record-size 600 --producer-props bootstrap.servers=localhost:9072 for the test.
   
   |               |           20ms           |           100ms          |           500ms          |          1000ms          |
   |:-------------:|:------------------------:|:------------------------:|:------------------------:|:------------------------:|
   |  1 consumers  | 39698.292973 records/sec | 40225.261464 records/sec | 39047.247169 records/sec |                          |
   |  10 consumers | 39936.102236 records/sec | 39729.837108 records/sec | 42625.745951 records/sec |                          |
   |  50 consumers | 25144.581343 records/sec | 36324.010171 records/sec | 39603.960396 records/sec |                          |
   | 100 consumers | 16860.563143 records/sec | 28425.241615 records/sec | 35435.861091 records/sec | 36616.623947 records/sec |
   
   On the test-machine, a got these numbers. The only changes were made in the amount of consumers and topics and the parameter `fetch.max.wait`.
   
   As you can see, the procuder can write much more messages to Kafka, if the idling consumers are having a higher `fetch.max.wait`.
   
   As `fetch.min.bytes` is set to 1, there should be no latency-impact on executing activations.
   
   ## Related issue and scope
   <!--- Please include a link to a related issue if there is one. -->
   - [ ] I opened an issue to propose and discuss this change (#????)
   
   ## 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. -->
   
   - [ ] I signed an [Apache CLA](https://github.com/apache/incubator-openwhisk/blob/master/CONTRIBUTING.md).
   - [ ] 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.
   - [ ] My changes require further changes to the documentation.
   - [ ] I updated the documentation where necessary.
   
   

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