Thanks. We don't take github pull requests. To contribute your patch please follow the procedure at https://golang.org/doc/contribute.html . Note that at this point it will have to wait for the Go 1.7 release.

The Remove method was not in the original API because monitoring software of the kind that scrapes such output can often get confused by a disappearing map key.

I think any change to add a Remove method would need to justify its usefulness as outweighing potentially malfunctioning monitoring.

Well, the particular use case I have highlights this fairly well IMO. I have a service which maintains state of downstream services. The list of all downstream services is fluid-- since it is determined by a source of truth service. As such my service has some metrics for each downstream. Since I cannot call "remove" i effectively leak N metrics per service that appears and then gets removed, since I cannot remove the metrics associated with that service.

I don't think adding a Remove method immediately constitutes "breaking monitoring" as it would still require the developer to actually call Remove.

Is there any disagreement with or recommended workaround for @jacksontj's use case?

I have exactly the same issue as @jacksontj. I don't buy the "borgmon can't handle it so we didn't add this API" argument. We expose a wealth of information over expvar that is useful for troubleshooting problems, how this gets consumed/stored by a particular monitoring backend isn't really the point.

Looks like the Kapacitor project already forked the code of expvar for this reason https://github.com/influxdata/kapacitor/blob/master/expvar/expvar.go (and made some other nice improvements such as influxdata/kapacitor#394). See this post for more info: https://www.influxdata.com/blog/influxdb-debugvars-endpoint/

The first reason they give why they forked the code:

it does not allow you to remove published variables.

Moving this to proposal so that it gets some visibility.

OK, it does seem like this is missing from expvar.Map's methods.
It should be called Delete though (like the builtin).

Change https://golang.org/cl/139537 mentions this issue: expvar: add Map.Delete