Query regarding flink metric types

["V N, Suchithra (Nokia - IN/Bangalore)" <su...@nokia.com>]

Hi Community,

Need some information regarding metrics type mentioned in flink documentation.
https://ci.apache.org/projects/flink/flink-docs-stable/ops/metrics.html

For the checkpoint metrics, below metrics are defined as of type gauge. As per my understanding gauge type is used to represent a value which can increase/decrease whereas counter is used to represent a value which will keep increasing. Below metrics will be keep increasing during the job run. Hence counter can be appropriate metric type for these. Please share your input on this.

numberOfCompletedCheckpoints
The number of successfully completed checkpoints.
Gauge
numberOfFailedCheckpoints
The number of failed checkpoints.
Gauge
totalNumberOfCheckpoints
The number of total checkpoints (in progress, completed, failed).
Gauge

Also "isBackPressured"  metric by the name it indicates as it returns boolean value Yes/No. Flink documentation says backpressure is measured as below,

  *   OK: 0 <= Ratio <= 0.10
  *   LOW: 0.10 < Ratio <= 0.5
  *   HIGH: 0.5 < Ratio <= 1
What exactly this metric reports ?

isBackPressured
Whether the task is back-pressured.
Gauge

Thanks,
Suchithra

Re: Query regarding flink metric types

[Roman Khachatryan <ro...@apache.org>]

Hi Suchithra,

You are right, those metrics can only grow, at least until failover.

isBackPressured is reported as a boolean on subtask level. These samples
are then aggregated and a ratio of (times-back-pressured /
number-of-samples) is reported to the JobManager.

Regards,
Roman


On Fri, Apr 9, 2021 at 12:44 PM V N, Suchithra (Nokia - IN/Bangalore) <
suchithra.v_n@nokia.com> wrote:

> Hi Community,
>
>
>
> Need some information regarding metrics type mentioned in flink
> documentation.
>
> https://ci.apache.org/projects/flink/flink-docs-stable/ops/metrics.html
>
>
>
> For the checkpoint metrics, below metrics are defined as of type gauge. As
> per my understanding gauge type is used to represent a value which can
> increase/decrease whereas counter is used to represent a value which will
> keep increasing. Below metrics will be keep increasing during the job run.
> Hence counter can be appropriate metric type for these. Please share your
> input on this.
>
>
>
> numberOfCompletedCheckpoints
>
> The number of successfully completed checkpoints.
>
> Gauge
>
> numberOfFailedCheckpoints
>
> The number of failed checkpoints.
>
> Gauge
>
> totalNumberOfCheckpoints
>
> The number of total checkpoints (in progress, completed, failed).
>
> Gauge
>
>
>
> Also “isBackPressured"  metric by the name it indicates as it returns
> boolean value Yes/No. Flink documentation says backpressure is measured as
> below,
>
>    - *OK*: 0 <= Ratio <= 0.10
>    - *LOW*: 0.10 < Ratio <= 0.5
>    - *HIGH*: 0.5 < Ratio <= 1
>
> What exactly this metric reports ?
>
>
>
> isBackPressured
>
> Whether the task is back-pressured.
>
> Gauge
>
>
>
> Thanks,
>
> Suchithra
>