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bwplotka
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bwplotka
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Nice! I think it makes sense but needed to research on my own WHY so some comment what are the rationales would be useful.
Let me know if I am wrong here, but the reason is that:
GOMAXPROCS is set properly in non-containerized guest thanks to:
As of Go 1.5, the default value of GOMAXPROCS is the number of CPUs (whatever your operating system considers to be a CPU) visible to the program at startup.
note: the number of operating system threads in use by a Go program includes threads servicing cgo calls, thread blocked on operating system calls, and may be larger than the value of GOMAXPROCS.
However in cgroup based container, despite cgroup limit/quotas container still see all the host CPUs, right?
| level.Debug(logger).Log("msg", fmt.Sprintf(template, args)) | ||
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| undo, err := maxprocs.Set(maxprocs.Logger(loggerAdapter)) |
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Can we comment on what are rationales? Why we are doing this?
There is almost 0 docs on https://github.com/uber-go/automaxprocs
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@bwplotka yep, you're right, app running in container will see all CPUs on host. maxprocs.Set() calculates GOMAXPROCS more accurate because also uses cgroup limits.
It's pretty convenient to configure CPU limits in one place when you're setting them for container and don't mind about GOMAXPROCS at all :)
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Added comment and force-pushed amended commit - will github switch to the new commit automatically or I need to make some additional actions? First time merge requesting so sorry for newbie questions. :)
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It's ok, GitHub will take care of this automatically 👍
Signed-off-by: Alexander Tunik <2braven@gmail.com>
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Changelog item is missing, but we can add it later (before tomorrow's release) |
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Changes
Add uber-go/automaxprocs integration to automatically set maxprocs value according to cgroup limit or $GOMAXPROCS env variable
Verification
Run any thanos component with --log.level=debug in docker container with cpus limit or not empty env variable GOMAXPROCS and see debug log message from library which value has been set for golang maxprocs.