wu-sheng commented on issue #5997: URL: https://github.com/apache/skywalking/issues/5997#issuecomment-743725407
> My previous understanding is that if I only set sampleRate for server side, the headers will still be added for every message and stored in Kafka brokers (kafka storage and the traffic for sending it to brokers are not affected by this option, so the overhead may be un-negligible under a high amount of throughput). That's why I want a "client side" sampling. I'm not very sure of this behavior so please correct me if this is not the fact. First of all, the so-called service-side `samplingRate` has nothing about transportation, no matter for gRPC or Kafka. This is not related. > The sample n in 3 seconds client config works for us, but a percentage one would be easier to reason about when specifying this option since different topics may have different messages per seconds, in which case a percentage sampling rate seems more suitable I think you have a misunderstanding about the sampling. It is not just for the network, sampling at the client side is for reducing the whole agent load, including tracing context, header injection/extraction, span creation/operations, etc. are all not working if not sampling. Kafka reporter is just a pluggable and optional thing. No core-level mechanism related to it. ___ The key of all these things, SkyWalking is targeting the APM, rather than just tracing. So, metrics and topology really matter. Any sampling mechanism at the client side would have a side-effect on this. We can't have a clear scenario about sampling rate(client-side) is better than the current one. Our final agenda is using `on building` [SkyWalking Satellite](https://github.com/apache/skywalking-satellite), which could be deployed as a sidecar, so no network cost. Then it will analyze the traces to get metrics(we call those **sources**) and forward to the OAP. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
