ASF GitHub Bot updated STORM-2909:
    Labels: pull-request-available  (was: )

> New Metrics Reporting API - for 2.0.0
> -------------------------------------
>                 Key: STORM-2909
>                 URL: https://issues.apache.org/jira/browse/STORM-2909
>             Project: Apache Storm
>          Issue Type: Improvement
>          Components: storm-client
>    Affects Versions: 2.0.0
>            Reporter: P. Taylor Goetz
>            Assignee: P. Taylor Goetz
>            Priority: Blocker
>              Labels: pull-request-available
> This is a proposal to provide a new metrics reporting API based on [Coda 
> Hale's metrics library | http://metrics.dropwizard.io/3.1.0/] (AKA 
> Dropwizard/Yammer metrics).
> h2. Background
> In a [discussion on the dev@ mailing list | 
> http://mail-archives.apache.org/mod_mbox/storm-dev/201610.mbox/%3ccagx0urh85nfh0pbph11pmc1oof6htycjcxsxgwp2nnofukq...@mail.gmail.com%3e]
>   a number of community and PMC members recommended replacing Storm’s metrics 
> system with a new API as opposed to enhancing the existing metrics system. 
> Some of the objections to the existing metrics API include:
> # Metrics are reported as an untyped Java object, making it very difficult to 
> reason about how to report it (e.g. is it a gauge, a counter, etc.?)
> # It is difficult to determine if metrics coming into the consumer are 
> pre-aggregated or not.
> # Storm’s metrics collection occurs through a specialized bolt, which in 
> addition to potentially affecting system performance, complicates certain 
> types of aggregation when the parallelism of that bolt is greater than one.
> In the discussion on the developer mailing list, there is growing consensus 
> for replacing Storm’s metrics API with a new API based on Coda Hale’s metrics 
> library. This approach has the following benefits:
> # Coda Hale’s metrics library is very stable, performant, well thought out, 
> and widely adopted among open source projects (e.g. Kafka).
> # The metrics library provides many existing metric types: Meters, Gauges, 
> Counters, Histograms, and more.
> # The library has a pluggable “reporter” API for publishing metrics to 
> various systems, with existing implementations for: JMX, console, CSV, SLF4J, 
> Graphite, Ganglia.
> # Reporters are straightforward to implement, and can be reused by any 
> project that uses the metrics library (i.e. would have broader application 
> outside of Storm)
> As noted earlier, the metrics library supports pluggable reporters for 
> sending metrics data to other systems, and implementing a reporter is fairly 
> straightforward (an example reporter implementation can be found here). For 
> example if someone develops a reporter based on Coda Hale’s metrics, it could 
> not only be used for pushing Storm metrics, but also for any system that used 
> the metrics library, such as Kafka.
> h2. Scope of Effort
> The effort to implement a new metrics API for Storm can be broken down into 
> the following development areas:
> # Implement API for Storms internal worker metrics: latencies, queue sizes, 
> capacity, etc.
> # Implement API for user defined, topology-specific metrics (exposed via the 
> {{org.apache.storm.task.TopologyContext}} class)
> # Implement API for storm daemons: nimbus, supervisor, etc.
> h2. Relationship to Existing Metrics
> This would be a new API that would not affect the existing metrics API. Upon 
> completion, the old metrics API would presumably be deprecated, but kept in 
> place for backward compatibility.
> Internally the current metrics API uses Storm bolts for the reporting 
> mechanism. The proposed metrics API would not depend on any of Storm's 
> messaging capabilities and instead use the [metrics library's built-in 
> reporter mechanism | 
> http://metrics.dropwizard.io/3.1.0/manual/core/#man-core-reporters]. This 
> would allow users to use existing {{Reporter}} implementations which are not 
> Storm-specific, and would simplify the process of collecting metrics. 
> Compared to Storm's {{IMetricCollector}} interface, implementing a reporter 
> for the metrics library is much more straightforward (an example can be found 
> [here | 
> https://github.com/dropwizard/metrics/blob/3.2-development/metrics-core/src/main/java/com/codahale/metrics/ConsoleReporter.java].
> The new metrics capability would not use or affect the ZooKeeper-based 
> metrics used by Storm UI.
> h2. Relationship to JStorm Metrics
> [TBD]
> h2. Target Branches
> [TBD]
> h2. Performance Implications
> [TBD]
> h2. Metrics Namespaces
> [TBD]
> h2. Metrics Collected
> *Worker*
> || Namespace || Metric Type || Description ||
> *Nimbus*
> || Namespace || Metric Type || Description ||
> *Supervisor*
> || Namespace || Metric Type || Description ||
> h2. User-Defined Metrics
> [TBD]

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