Increase ConfigurationDiscoveryService priority and set initial delay to zero.

[weixiang1862]

I want increase ConfigurationDiscoveryService priority(right after GRPCChannelManager) and set sync config task initial delay to zero. It can help agent receive config from backend as early as possible.

[wu-sheng]

What do you mean by priority? I don't think there is such a mechanism in the agent services.

[weixiang1862]

Yes, I agree, SkyWalking should focus on self. So, let‘s look about a case in skywalking APM use:

User use cds to control agent agent.ignore_suffix and agent.trace.ignore_path, he may hope this value can overide default value in agent.config, although SkyWalking has no such guarantee in settings override priority.

Then, in the first 20s after boot, agent works on default config and later agent works on remote config. I think this inconsistent time can be optimized by cds sync task initial delay.

If you think set initial delay to zero is too extreme, how about make it value configurable in agent.config and default to 20s? At least user get the chance to control this.

We already have diff in code with SkyWalking and must do sync between two repo in the feature, we don't mind introduce more changes. I start this discussion just because I think this optimization is meaningful to SkyWalking self. I am a fresh man in SW and has a very narrow view of landscape, I learned a lot from this discussion, thanks. The discuss result is not important, I think and trust you can make the best decision.

[wu-sheng]

Isn't it already in the agent.config?

[weixiang1862]

No, just GET_AGENT_DYNAMIC_CONFIG_INTERVAL, it controls both initial delay and schedule period.

[wu-sheng]

I can't see why the first 20s matters. Most services can't even boot in 20s.

Then, in the first 20s after boot, agent works on default config and later agent works on remote config. I think this inconsistent time can be optimized by cds sync task initial delay.

If you really care about the latency, why don't you inject the latest values through the system environment? The point of introducing dynamic configurations is to change the values in the runtime, rather than making all agents running by default and then updated later.

[weixiang1862]

Ok, thanks. Inject by system environment is a good way for this case.