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Posted to issues@flink.apache.org by "Richard Deurwaarder (JIRA)" <ji...@apache.org> on 2019/04/24 18:19:00 UTC
[jira] [Updated] (FLINK-12325) Statsd reporter gives wrong metrics
when using negative numbers
[ https://issues.apache.org/jira/browse/FLINK-12325?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Richard Deurwaarder updated FLINK-12325:
----------------------------------------
Description:
The statsd reporter has a bug I believe when using negative numbers.
This is because when a metric is sent it is first converted to a string value. This means 100 becomes "100" and -100 becomes "-100". This value is then sent to statsd as a gauge value.
See this line for the conversion to string: [https://github.com/apache/flink/blob/master/flink-metrics/flink-metrics-statsd/src/main/java/org/apache/flink/metrics/statsd/StatsDReporter.java#L130]
And this line for sending it as a gauge:
[https://github.com/apache/flink/blob/master/flink-metrics/flink-metrics-statsd/src/main/java/org/apache/flink/metrics/statsd/StatsDReporter.java#L184]
This means a value of -100 will be sent like this:
{code:java}
<metric_name>:-100|g{code}
The statsd protocol how ever states the following ([https://github.com/statsd/statsd/blob/master/docs/metric_types.md#gauges]):
{noformat}
Adding a sign to the gauge value will change the value, rather than setting it.
{noformat}
So sending -100 multiple times means the gauge in statsd will be decremented multiple times, rather than set to -100.
I believe this isn't how flink expects it to work, isn't it?
was:
The statsd reporter has a bug I believe when using negative numbers.
This is because when a metric is sent it is first converted to a string value. This means 100 becomes "100" and -100 becomes "-100". This value is then sent to statsd as a gauge value.
See this line for the conversion to string: [https://github.com/apache/flink/blob/master/flink-metrics/flink-metrics-statsd/src/main/java/org/apache/flink/metrics/statsd/StatsDReporter.java#L130]
And this line for sending it as a gauge:
[https://github.com/apache/flink/blob/master/flink-metrics/flink-metrics-statsd/src/main/java/org/apache/flink/metrics/statsd/StatsDReporter.java#L184]
So a value of -100 will be sent like this:
{code:java}
<metric_name>:-100|g{code}
The statsd protocol how ever states the following ([https://github.com/statsd/statsd/blob/master/docs/metric_types.md#gauges]):
{noformat}
Adding a sign to the gauge value will change the value, rather than setting it.
{noformat}
So sending -100 multiple times means the gauge in statsd will be decremented multiple times, rather than set to -100.
I believe this isn't how flink expects it to work, isn't it?
> Statsd reporter gives wrong metrics when using negative numbers
> ---------------------------------------------------------------
>
> Key: FLINK-12325
> URL: https://issues.apache.org/jira/browse/FLINK-12325
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Metrics
> Affects Versions: 1.6.4, 1.7.2, 1.8.0
> Reporter: Richard Deurwaarder
> Priority: Minor
>
> The statsd reporter has a bug I believe when using negative numbers.
>
> This is because when a metric is sent it is first converted to a string value. This means 100 becomes "100" and -100 becomes "-100". This value is then sent to statsd as a gauge value.
> See this line for the conversion to string: [https://github.com/apache/flink/blob/master/flink-metrics/flink-metrics-statsd/src/main/java/org/apache/flink/metrics/statsd/StatsDReporter.java#L130]
> And this line for sending it as a gauge:
> [https://github.com/apache/flink/blob/master/flink-metrics/flink-metrics-statsd/src/main/java/org/apache/flink/metrics/statsd/StatsDReporter.java#L184]
>
> This means a value of -100 will be sent like this:
> {code:java}
> <metric_name>:-100|g{code}
>
> The statsd protocol how ever states the following ([https://github.com/statsd/statsd/blob/master/docs/metric_types.md#gauges]):
> {noformat}
> Adding a sign to the gauge value will change the value, rather than setting it.
> {noformat}
>
>
> So sending -100 multiple times means the gauge in statsd will be decremented multiple times, rather than set to -100.
>
> I believe this isn't how flink expects it to work, isn't it?
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