gotosocial/vendor/go.uber.org/automaxprocs/internal/cgroups/cgroups2.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

152 lines
4 KiB
Go

// Copyright (c) 2022 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//go:build linux
// +build linux
package cgroups
import (
"bufio"
"errors"
"fmt"
"io"
"os"
"path"
"strconv"
"strings"
)
const (
// _cgroupv2CPUMax is the file name for the CGroup-V2 CPU max and period
// parameter.
_cgroupv2CPUMax = "cpu.max"
// _cgroupFSType is the Linux CGroup-V2 file system type used in
// `/proc/$PID/mountinfo`.
_cgroupv2FSType = "cgroup2"
_cgroupv2MountPoint = "/sys/fs/cgroup"
_cgroupV2CPUMaxDefaultPeriod = 100000
_cgroupV2CPUMaxQuotaMax = "max"
)
const (
_cgroupv2CPUMaxQuotaIndex = iota
_cgroupv2CPUMaxPeriodIndex
)
// ErrNotV2 indicates that the system is not using cgroups2.
var ErrNotV2 = errors.New("not using cgroups2")
// CGroups2 provides access to cgroups data for systems using cgroups2.
type CGroups2 struct {
mountPoint string
cpuMaxFile string
}
// NewCGroups2ForCurrentProcess builds a CGroups2 for the current process.
//
// This returns ErrNotV2 if the system is not using cgroups2.
func NewCGroups2ForCurrentProcess() (*CGroups2, error) {
return newCGroups2FromMountInfo(_procPathMountInfo)
}
func newCGroups2FromMountInfo(mountInfoPath string) (*CGroups2, error) {
isV2, err := isCGroupV2(mountInfoPath)
if err != nil {
return nil, err
}
if !isV2 {
return nil, ErrNotV2
}
return &CGroups2{
mountPoint: _cgroupv2MountPoint,
cpuMaxFile: _cgroupv2CPUMax,
}, nil
}
func isCGroupV2(procPathMountInfo string) (bool, error) {
var (
isV2 bool
newMountPoint = func(mp *MountPoint) error {
isV2 = isV2 || (mp.FSType == _cgroupv2FSType && mp.MountPoint == _cgroupv2MountPoint)
return nil
}
)
if err := parseMountInfo(procPathMountInfo, newMountPoint); err != nil {
return false, err
}
return isV2, nil
}
// CPUQuota returns the CPU quota applied with the CPU cgroup2 controller.
// It is a result of reading cpu quota and period from cpu.max file.
// It will return `cpu.max / cpu.period`. If cpu.max is set to max, it returns
// (-1, false, nil)
func (cg *CGroups2) CPUQuota() (float64, bool, error) {
cpuMaxParams, err := os.Open(path.Join(cg.mountPoint, cg.cpuMaxFile))
if err != nil {
if os.IsNotExist(err) {
return -1, false, nil
}
return -1, false, err
}
scanner := bufio.NewScanner(cpuMaxParams)
if scanner.Scan() {
fields := strings.Fields(scanner.Text())
if len(fields) == 0 || len(fields) > 2 {
return -1, false, fmt.Errorf("invalid format")
}
if fields[_cgroupv2CPUMaxQuotaIndex] == _cgroupV2CPUMaxQuotaMax {
return -1, false, nil
}
max, err := strconv.Atoi(fields[_cgroupv2CPUMaxQuotaIndex])
if err != nil {
return -1, false, err
}
var period int
if len(fields) == 1 {
period = _cgroupV2CPUMaxDefaultPeriod
} else {
period, err = strconv.Atoi(fields[_cgroupv2CPUMaxPeriodIndex])
if err != nil {
return -1, false, err
}
}
return float64(max) / float64(period), true, nil
}
if err := scanner.Err(); err != nil {
return -1, false, err
}
return 0, false, io.ErrUnexpectedEOF
}