Is em.Clone redundant? about cloudprober HOT 7 CLOSED

Clone does the new application for a piece of memory and then returns

from cloudprober.

Good catch, @MrDragon1122. This Clone() is indeed unnecessary. I had a change to fix it long time ago, but didn't follow through and forgot about it :)

Do you want to send a PR?

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Thanks for your guidance.
I also found a problem in the test, that is, the data in the Prometheus interface may be stale. If the prometheus database receives older data (such as 7 days ago), it will report an error. Therefore, the time should be added when the interface writes data, and the old data is not sent.

	if ps.c.IncludeTimeStamp {
		ps.dataWriter = func(w io.Writer, pm *promMetric, key string) {
			**if promTime(time.Now())-pm.data[key].timestamp < 60*60000 {**
				fmt.Fprintf(w, "%s %s %d\n", key, pm.data[key].value, pm.data[key].timestamp)
			}
		}
	} else {
		ps.dataWriter = func(w io.Writer, pm *promMetric, key string) {
			**if promTime(time.Now())-pm.data[key].timestamp < 60*60000 {**
				fmt.Fprintf(w, "%s %s\n", key, pm.data[key].value)
			}
		}
	}

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@MrDragon1122

It's only a non-default option to not specify timestamp in prometheus surfacer. We added that because someone had an issue exporting data because of time-synchronization issues.

Am I understanding your concern correctly?

from cloudprober.

Ah, I see now. You're saying that we should not export data that is too old (especially when we are exporting timestamp with the data) as that may make prometheus reject all data instead of just the one that is old. That seems like a fair point. Let me think more about that.

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@MrDragon1122 Can you point me to the prometheus documentation or code that says that it will reject the whole scrape if a metric has a timestamp older than 7d. Or, let me know if I didn't understand the issue clearly.

Also, cloudprober, by itself, re-exports all the relatively unchanging sysvar values, e.g. hostname, environment variables, etc and all the system probes should also keep generating new data unless there is a bug. I was wondering how did you run into a case where data was older than 7 days.

Also, I think we should file another issue for the prometheus surfacer issue.

Thanks in advance.
Manu

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Committed 5d59e2c to fix the Clone() issue.

@MrDragon1122 Can you please create a different issue for the prometheus question. I'd do it myself but I think I am not clear about what's the real issue there. Appreciate you looking at it.

Thanks,
Manu

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