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

Jump to bottom

x/tools/cmd/goimports: recent commit using 700% of CPU #40743

Open
kevinburke1 opened this issue Aug 12, 2020 · 5 comments
Open

x/tools/cmd/goimports: recent commit using 700% of CPU #40743

kevinburke1 opened this issue Aug 12, 2020 · 5 comments
Labels
NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. Performance Tools This label describes issues relating to any tools in the x/tools repository.
Milestone
Unreleased

Comments

@kevinburke1
Copy link

kevinburke1 commented Aug 12, 2020 •
edited

I try to stay close to the tip of x/tools (generally compiling every day or other day). Today I noticed goimports using 700% of my CPU after several hours of the fan being on (not unusual for the fan to go on on my machine, but unusual for it to go for several hours.) I'm running darwin and Go tip. It was not using that much RAM. It had been running for at least 7 hours according to Activity Monitor.

I'm not sure of the best way to troubleshoot that problem going forward, just wanted to make you aware of it in case you notice it on your machine or can think of a recent commit that could cause the CPU to spin.
@gopherbot gopherbot added the Tools This label describes issues relating to any tools in the x/tools repository. label Aug 12, 2020
@gopherbot gopherbot added this to the Unreleased milestone Aug 12, 2020
@mdempsky
Copy link
Member

Is the process still alive? If you can get a few backtraces from it, that might be interesting to help track down where/why it's using up so much CPU.

@kevinburke1
Copy link
Author

No, it was running in the background in a Vim session. Can you describe how to get backtraces? I can try it if it happens again.

@mdempsky
Copy link
Member

The intrusive way is to use kill -ABRT, which should cause it to immediately exit and print a backtrace. See the documentation at https://golang.org/pkg/runtime/ for "The GOTRACEBACK variable" for more ways to control this backtrace output using environment variables.

A somewhat better approach would be to attach a debugger to the process, grab a backtrace, let the process continue again for a couple seconds, grab another backtrace, etc., until you've got maybe 3 or more backtraces. That would give us a good idea where goimports is spending all its CPU time.

However, I don't actually have much experience using debuggers, and much less on macOS. Maybe someone else can suggest the best way to proceed there. I would think lldb should work though.

@kevinburke1
Copy link
Author

I've used strace -f to attach to a running process before on Mac, though if it's not interacting with the filesystem that won't help much, could try that.

@dmitshur dmitshur changed the title x/tools: recent goimports build using 700% of CPU x/tools/cmd/goimports: recent commit using 700% of CPU Aug 17, 2020
@dmitshur dmitshur added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Aug 17, 2020
@dmitshur
Copy link
Contributor

/cc @heschik per owners.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. Performance Tools This label describes issues relating to any tools in the x/tools repository.
Projects
None yet
Milestone
Unreleased
Development

No branches or pull requests
4 participants
@mdempsky @dmitshur @gopherbot @kevinburke1