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https://issues.apache.org/jira/browse/FLINK-3660?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15476390#comment-15476390
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ASF GitHub Bot commented on FLINK-3660:
---------------------------------------
Github user aljoscha commented on a diff in the pull request:
https://github.com/apache/flink/pull/2386#discussion_r78148223
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/operators/AbstractStreamOperator.java
---
@@ -322,6 +346,151 @@ public final ChainingStrategy getChainingStrategy() {
return chainingStrategy;
}
+
+ //
------------------------------------------------------------------------
+ // Metrics
+ //
------------------------------------------------------------------------
+
+ // ------- One input stream
+ public void processLatencyMarker(LatencyMarker latencyMarker) throws
Exception {
+ reportOrForwardLatencyMarker(latencyMarker);
+ }
+
+ // ------- Two input stream
+ public void processLatencyMarker1(LatencyMarker latencyMarker) throws
Exception {
+ reportOrForwardLatencyMarker(latencyMarker);
+ }
+
+ public void processLatencyMarker2(LatencyMarker latencyMarker) throws
Exception {
+ reportOrForwardLatencyMarker(latencyMarker);
+ }
+
+
+ protected void reportOrForwardLatencyMarker(LatencyMarker maker) {
+ if(isSink) {
--- End diff --
Don't all operators now keep the latency statistics?
> Measure latency of elements and expose it through web interface
> ---------------------------------------------------------------
>
> Key: FLINK-3660
> URL: https://issues.apache.org/jira/browse/FLINK-3660
> Project: Flink
> Issue Type: Sub-task
> Components: Streaming
> Reporter: Robert Metzger
> Assignee: Robert Metzger
> Fix For: pre-apache
>
>
> It would be nice to expose the end-to-end latency of a streaming job in the
> webinterface.
> To achieve this, my initial thought was to attach an ingestion-time timestamp
> at the sources to each record.
> However, this introduces overhead for a monitoring feature users might not
> even use (8 bytes for each element + System.currentTimeMilis() on each
> element).
> Therefore, I suggest to implement this feature by periodically sending
> special events, similar to watermarks through the topology.
> Those {{LatencyMarks}} are emitted at a configurable interval at the sources
> and forwarded by the tasks. The sinks will compare the timestamp of the
> latency marks with their current system time to determine the latency.
> The latency marks will not add to the latency of a job, but the marks will be
> delayed similarly than regular records, so their latency will approximate the
> record latency.
> Above suggestion expects the clocks on all taskmanagers to be in sync.
> Otherwise, the measured latencies would also include the offsets between the
> taskmanager's clocks.
> In a second step, we can try to mitigate the issue by using the JobManager as
> a central timing service. The TaskManagers will periodically query the JM for
> the current time in order to determine the offset with their clock.
> This offset would still include the network latency between TM and JM but it
> would still lead to reasonably good estimations.
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