Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

cmd/go: go list cmd/compile takes 40x longer than go list cmd/... #60455

Closed
findleyr opened this issue May 26, 2023 · 5 comments
Closed

cmd/go: go list cmd/compile takes 40x longer than go list cmd/... #60455

findleyr opened this issue May 26, 2023 · 5 comments
Assignees
Labels
compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge GoCommand cmd/go NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. release-blocker
Milestone

Comments

@findleyr
Copy link
Contributor

As in the title:

> time go list cmd/compile
cmd/compile

real	0m8.523s
user	0m8.610s
sys	0m0.068s

vs

> time go list cmd/...
...output, including cmd/compile

real	0m0.200s
user	0m0.492s
sys	0m0.185s

Here is my go version:

> go version
go version devel go1.21-e51b5f8384 Thu May 25 10:06:01 2023 -0700 linux/amd64

CC @bcmills @matloob @adonovan

@bcmills
Copy link
Contributor

bcmills commented May 26, 2023

This is likely another PGO issue, or another symptom of the same PGO issue. Probably closely related to #60428.
(attn @cherrymui @prattmic)

@bcmills bcmills added NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. GoCommand cmd/go compiler/runtime Issues related to the Go compiler and/or runtime. labels May 26, 2023
@bcmills bcmills added this to the Go1.21 milestone May 26, 2023
@findleyr
Copy link
Contributor Author

I can confirm that go list -pgo=off cmd/compile is ~instantaneous.

@prattmic
Copy link
Member

image

😬

@prattmic
Copy link
Member

The problem is this section: https://cs.opensource.google/go/go/+/refs/heads/master:src/cmd/go/internal/load/pkg.go;l=2976-2981;drc=01b5cce626c44f7fd1ca7e2c076d63c175193ccf

For the copying block above we have a map to avoid copying more than once, but the modification block I linked to runs (recursively!) every time we encounter a package. So if I import "io" and "bufio", we'll visit "io" and all of its dependencies, then we'll visit "bufio" and its dependencies. One of its dependencies is "io", so we'll visit that whole tree again.

I'll send a CL later today.

@gopherbot
Copy link
Contributor

Change https://go.dev/cl/498735 mentions this issue: cmd/go: always track visited packages in setPGOProfilePath

@golang golang locked and limited conversation to collaborators May 26, 2024
Sign up for free to subscribe to this conversation on GitHub. Already have an account? Sign in.
Labels
compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge GoCommand cmd/go NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. release-blocker
Projects
None yet
Development

No branches or pull requests

4 participants