[BROOKLYN-171] Mapping propagated sensor causes excessive CPU load

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.9.0
• Assignee: Unassigned
• Reporter: Martin Harris
• Created: 10/Sep/15 13:01
• Updated: 14/Sep/15 17:29
• Resolved: 14/Sep/15 17:29

Description

Mapping a propagated sensor using a second propagator will cause excessive CPU load, and the sensor will fail to propagate. This can be demonstrated using the following YAML:

location: localhost
services:
- type: org.apache.brooklyn.entity.stock.BasicApplication
  brooklyn.children:
  - type: org.apache.brooklyn.entity.software.base.EmptySoftwareProcess
    id: childid

  brooklyn.enrichers:
  - type: org.apache.brooklyn.enricher.stock.Propagator
    brooklyn.config:
      producer: $brooklyn:component("child", "childid")
      propagating:
      - $brooklyn:sensor("host.name")
  - type: org.apache.brooklyn.enricher.stock.Propagator
    brooklyn.config:
      sensorMapping:
        $brooklyn:sensor("host.name"): $brooklyn:sensor("host")

Running this YAML will cause CPU load on my machine to run to around 600% CPU, and cause the Brooklyn console to become unresponsive. The specs of my machine are as follows:

Model Name: MacBook Pro
Model Identifier: MacBookPro11,3
Processor Name: Intel Core i7
Processor Speed: 2.8 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 16 GB

Context (aka 'Why would you ever want to do this??'):

The Redis cluster propagates the hostname of the master RedisStore up to the cluster level [1]. We then added (in the YAML) a propagator with `sensorMapping` to map the sensor `host.name` to `host` in order for it to be consumed by a third party application (CloudFoundry via the Brooklyn-Service-Broker[2])

In this scenario (i.e. Redis, deploying to AWS from a rBrooklyn server), the server web interface becomes completely unresponsive until the Brooklyn process is terminated and restarted

[1]: https://github.com/apache/incubator-brooklyn/blob/6f15e8a6d61c2e648547cf7faba03fbc06716421/software/nosql/src/main/java/org/apache/brooklyn/entity/nosql/redis/RedisClusterImpl.java#L73-L76
[2]: https://github.com/cloudfoundry-incubator/brooklyn-service-broker