Hi Shane, Could you share more information on what you would like to use the counter for?
The counter discussed here is primarily designed for exposing counts to external metric systems. Usually, each task would count on its own, and it is left for the external metric system (usu. a time series database) to do aggregations. Also, you cannot reference a counter from a different machine. I'm not sure if this is what you expected. Best, Zhanghao Chen ________________________________ From: Shane Bishop <shane.bis...@outlook.com> Sent: Saturday, March 5, 2022 23:22 To: Zhanghao Chen <zhanghao.c...@outlook.com>; user@flink.apache.org <user@flink.apache.org> Subject: Re: Question about Flink counters If I used a thread-safe counter implementation, would that be enough to make the count correct for a Flink cluster with multiple machines? Best, Shane ________________________________ From: Zhanghao Chen <zhanghao.c...@outlook.com> Sent: March 4, 2022 11:08 PM To: Shane Bishop <shane.bis...@outlook.com>; user@flink.apache.org <user@flink.apache.org> Subject: Re: Question about Flink counters Hi Shane, Flink provides a generic counter interface with a few implementations. The default implementation SimpleCounter, which is not thread-safe, is used when you calling counter(String name) on a MetricGroup. Therefore, you'll need to use your own thread-safe implementation, check out the second example of Metrics | Apache Flink<https://nightlies.apache.org/flink/flink-docs-release-1.14/docs/ops/metrics/#counter> for reference. Best, Zhanghao Chen ________________________________ From: Shane Bishop <shane.bis...@outlook.com> Sent: Saturday, March 5, 2022 5:24 To: user@flink.apache.org <user@flink.apache.org> Subject: Question about Flink counters Hi all, For Flink counters [1], are increment operations guaranteed to be atomic across all parallel tasks? I.e., is there a guarantee that the counter values will not be higher than expected? Thanks, Shane --- [1] https://nightlies.apache.org/flink/flink-docs-release-1.14/docs/ops/metrics/#counter
