net/http/pprof: URL path /debug/pprof does not list all the available endpoints

[MikeSpreitzer]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

Whatever is in the Docker image quay.io/coreos/hyperkube:v1.8.7_coreos.0.

Here is a possibly informative entry from its /metrics:

kubernetes_build_info{buildDate="2018-01-18T00:17:18Z",compiler="gc",gitCommit="768e049ab5230010251f30475e0e785e2e999566",gitTreeState="clean",gitVersion="v1.8.7+coreos.0",goVersion="go1.8.3",major="1",minor="8+",platform="linux/amd64"}

Does this issue reproduce with the latest release?

I think it does.

What operating system and processor architecture are you using (go env)?

That is a Docker container image. I ran it on Ubuntu 16.04.1, on an Intel processor.

What did you do?

kubectl get --raw /debug/pprof --server https://10.233.110.91 --insecure-skip-tls-verify

What did you expect to see?

I expected to see the complete list of <foo> that makes for a valid path /debug/pprof/<foo>.

BTW, I can not find the complete list in any one central place. Different partial lists can be found: as shown here, in https://golang.org/pkg/net/http/pprof/ , in https://raywangblog.wordpress.com/2017/07/16/golang-profiling/ , and in https://blog.golang.org/profiling-go-programs . In another issue I finally saw a pointer to https://tip.golang.org/doc/diagnostics.html#profiling . But the full list should be in the main doc as well as what the runtime reports.

What did you see instead?

Fetching /debug/pprof got me the following list of choices:

<tr><td align=right>0<td><a href="block?debug=1">block</a>
<tr><td align=right>64<td><a href="goroutine?debug=1">goroutine</a>
<tr><td align=right>18<td><a href="heap?debug=1">heap</a>
<tr><td align=right>0<td><a href="mutex?debug=1">mutex</a>
<tr><td align=right>15<td><a href="threadcreate?debug=1">threadcreate</a>

Astonishingly, profile is missing from that list! So is trace (which is mentioned in https://golang.org/pkg/net/http/pprof/ --- which, distressingly, does not say anything about ?debug=1).

[andybons]

/cc @hyangah

[hyangah]

agree that we need to extend net/http/pprof.Index to include the endpoints implemented outside runtime/pprof.Profiles, along with helpful description of endpoints.

Just we need to make sure the binary format outputs have correct Content-Type headers and browsers handle them appropriately. The reason debug=1 is specified for other profiles is that it outputs in the text format. For CPU profiles or execution trace, that option is not available.

[agnivade]

Taking this. The "/debug/pprof" endpoint is seriously lacking in clarity. It's not even clear what the nos. in the left column stand for.

[agnivade]

I am thinking of revamping the page a bit.

Couple of points to consider:

• The goroutine profiles of debug=1 and debug=2 should be under the same header. Currently, it is just a single link outside the list.
• non-runtime profiles don't have a count attribute. So we cannot just append to the pprof.Profiles() slice and iterate it in the template. Additional fields need to be added to denote whether a profile has a count field or not.
• Additionally, if we are to add a description field, it is better that we move away from the table format to a list format.

I will send a CL along with screenshots soon.

[hyangah]

Thanks!

Can you clarify what you mean by "non-runtime" profile in the second bullet?

[agnivade]

Can you clarify what you mean by "non-runtime" profile in the second bullet?

The endpoints implemented outside runtime/pprof.Profiles. AKA, those endpoints which are exposed from net/http/pprof.

[gopherbot]

Change https://golang.org/cl/112495 mentions this issue: net/http/pprof: update the /debug/pprof endpoint