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https://issues.apache.org/jira/browse/FLINK-7781?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16224590#comment-16224590
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ASF GitHub Bot commented on FLINK-7781:
---------------------------------------
Github user kl0u commented on a diff in the pull request:
https://github.com/apache/flink/pull/4901#discussion_r147655793
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/rest/handler/legacy/metrics/AbstractMetricsHandler.java
---
@@ -39,12 +39,15 @@
* <p>If the query parameters do not contain a "get" parameter the list of
all metrics is returned.
* {@code [ { "id" : "X" } ] }
*
- * <p>If the query parameters do contain a "get" parameter a
comma-separate list of metric names is expected as a value.
- * {@code /get?X,Y}
+ * <p>If the query parameters do contain a "get" parameter, a
comma-separated list of metric names is expected as a value.
+ * {@code /metrics?get=X,Y}
* The handler will then return a list containing the values of the
requested metrics.
* {@code [ { "id" : "X", "value" : "S" }, { "id" : "Y", "value" : "T" } ]
}
*/
public abstract class AbstractMetricsHandler extends
AbstractJsonRequestHandler {
+
--- End diff --
Why not putting all these (`PARAMETER_METRICS`, `PARAMETER_AGGREGATION`,
`SUBTASK_METRICS_REST_PATH` even `"/jobs/metrics"`, etc) in a
`MetricsURLConstants` class (or sth like this) so that there is a central place
for all? This could help maintenance.
> Support simple on-demand metrics aggregation
> --------------------------------------------
>
> Key: FLINK-7781
> URL: https://issues.apache.org/jira/browse/FLINK-7781
> Project: Flink
> Issue Type: Improvement
> Components: Metrics, REST
> Affects Versions: 1.4.0
> Reporter: Chesnay Schepler
> Assignee: Chesnay Schepler
> Fix For: 1.4.0
>
>
> We should support aggregations (min, max, avg, sum) of metrics in the REST
> API. This is primarily about aggregating across subtasks, for example the
> number of incoming records across all subtasks.
> This is useful for simple use-cases where a dedicated metrics backend is
> overkill, and will allow us to provide better metrics in the web UI (since we
> can expose these aggregated as well).
> I propose to add a new query parameter "agg=[min,max,avg,sum]". As a start
> this parameter should only be used for task metrics. (This is simply the main
> use-case i have in mind)
> The aggregation should (naturally) only work for numeric metrics.
> We will need a HashSet of metrics that exist for subtasks of a given tasks
> that has to be updated in {{MetricStore#add}}.
> All task metrics are either stored as
> # {{<subtask-index>.<metric>}} or
> # {{<subtask-index>.<operator-name>.<metric>}}.
> If a user sends a request {{get=mymetric,agg=sum}}, only the metrics of the
> first kind are to be considered. Similarly, given a request
> {{get=myoperator.mymetric,agg=sum}} only metrics of the second kind are to be
> considered.
> Ideally, the name of the aggregated metric (i.e. the original name without
> subtask index) is also contained in the list of available metrics.
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