Why does the Go agent use 1900 as the epoch time instead of Unix epoch (1970) for ID generation?

[zJiaJun]

I've been investigating the trace ID generation logic in the Go agent and noticed that it uses 1900 as the epoch time (idEpoch = time.Date(1900, 0, 0, 0, 0, 0, 0, time.UTC)) in plugins/core/id.go, while the Java agent uses Unix epoch (1970) for the same purpose.

https://github.com/apache/skywalking-go/blob/123380c0bf18e8ffcb99978e9bbb49c0986ac190/plugins/core/id.go#L36

func init() {
    idEpoch = time.Date(1900, 0, 0, 0, 0, 0, 0, time.UTC)
    // ...
}

func (c *IDContext) timestamp() int64 {
    now := time.Since(idEpoch).Milliseconds()
    // ...
}

This creates inconsistency between agents:
Java agent: Generates trace IDs like f45113f5a3544da7ab2130b834006ba4.329.17496288010000555 where the last part follows the format unix_timestamp_ms * 10000 + nextSeq()
Go agent: Generates trace IDs like 346911604a8e11f0a72b00163e023999.240.39618174077120001 where the last part uses time_since_1900_ms * 10000 + nextSeq()

Is there a specific reason why the Go agent uses 1900 as the epoch time?
Would it be acceptable to change this to Unix epoch (1970) for consistency?

[wu-sheng]

I think there isn't. As from current implementation, each agent picks their logic, and backend doesn't depend on the logic of the generation.

Are you doing some custom/private change to use that?

[zJiaJun]

Yes, I will customize and modify it for our usage scenario.

[wu-sheng]

I am fine if you want to align them.