gotosocial/vendor/github.com/containerd/cgroups/v2/paths.go
Daniele Sluijters acc333c40b
[feature] Inherit resource limits from cgroups (#1336)
When GTS is running in a container runtime which has configured CPU or
memory limits or under an init system that uses cgroups to impose CPU
and memory limits the values the Go runtime sees for GOMAXPROCS and
GOMEMLIMIT are still based on the host resources, not the cgroup.

At least for the throttling middlewares which use GOMAXPROCS to
configure their queue size, this can result in GTS running with values
too big compared to the resources that will actuall be available to it.

This introduces 2 dependencies which can pick up resource contraints
from the current cgroup and tune the Go runtime accordingly. This should
result in the different queues being appropriately sized and in general
more predictable performance. These dependencies are a no-op on
non-Linux systems or if running in a cgroup that doesn't set a limit on
CPU or memory.

The automatic tuning of GOMEMLIMIT can be disabled by either explicitly
setting GOMEMLIMIT yourself or by setting AUTOMEMLIMIT=off. The
automatic tuning of GOMAXPROCS can similarly be counteracted by setting
GOMAXPROCS yourself.
2023-01-17 20:59:04 +00:00

61 lines
1.8 KiB
Go

/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package v2
import (
"fmt"
"path/filepath"
"strings"
)
// NestedGroupPath will nest the cgroups based on the calling processes cgroup
// placing its child processes inside its own path
func NestedGroupPath(suffix string) (string, error) {
path, err := parseCgroupFile("/proc/self/cgroup")
if err != nil {
return "", err
}
return filepath.Join(path, suffix), nil
}
// PidGroupPath will return the correct cgroup paths for an existing process running inside a cgroup
// This is commonly used for the Load function to restore an existing container
func PidGroupPath(pid int) (string, error) {
p := fmt.Sprintf("/proc/%d/cgroup", pid)
return parseCgroupFile(p)
}
// VerifyGroupPath verifies the format of group path string g.
// The format is same as the third field in /proc/PID/cgroup.
// e.g. "/user.slice/user-1001.slice/session-1.scope"
//
// g must be a "clean" absolute path starts with "/", and must not contain "/sys/fs/cgroup" prefix.
//
// VerifyGroupPath doesn't verify whether g actually exists on the system.
func VerifyGroupPath(g string) error {
if !strings.HasPrefix(g, "/") {
return ErrInvalidGroupPath
}
if filepath.Clean(g) != g {
return ErrInvalidGroupPath
}
if strings.HasPrefix(g, "/sys/fs/cgroup") {
return ErrInvalidGroupPath
}
return nil
}