Mostafa Elhemali created HADOOP-9090:
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Summary: Refactor MetricsSystemImpl to allow for an on-demand
publish system
Key: HADOOP-9090
URL: https://issues.apache.org/jira/browse/HADOOP-9090
Project: Hadoop Common
Issue Type: New Feature
Components: metrics
Reporter: Mostafa Elhemali
Priority: Minor
Attachments: HADOOP-9090.patch
We have a need to publish metrics out of some short-living processes, which is
not really well-suited to the current metrics system implementation which
periodically publishes metrics asynchronously (a behavior that works great for
long-living processes). Of course I could write my own metrics system, but it
seems like such a waste to rewrite all the awesome code currently in the
MetricsSystemImpl and supporting classes.
The way I'm proposing to solve this is to:
1. Refactor the MetricsSystemImpl class into an abstract base MetricsSystemImpl
class (common configuration and other code) and a concrete
PeriodicPublishMetricsSystemImpl class (timer thread).
2. Refactor the MetricsSinkAdapter class into an abstract base
MetricsSinkAdapter class (common configuration and other code) and a concrete
AsyncMetricsSinkAdapter class (asynchronous publishing using the SinkQueue).
3. Derive a new simple class OnDemandPublishMetricsSystemImpl from
MetricsSystemImpl, that just exposes a synchronous publish() method to do all
the work.
4. Derive a SyncMetricsSinkAdapter class from MetricsSinkAdapter to just
synchronously push metrics to the underlying sink.
Does that sound reasonable? I'll attach the patch with all this coded up and
simple tests (could use some polish I guess, but wanted to get everyone's
opinion first). Notice that this is somewhat of a breaking change since
MetricsSystemImpl is public (although it's marked with
InterfaceAudience.Private); if the breaking change is a problem I could just
rename the refactored classes so that PeriodicPublishMetricsSystemImpl is still
called MetricsSystemImpl (and MetricsSystemImpl -> BaseMetricsSystemImpl).
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