133 lines
3.2 KiB
Go
133 lines
3.2 KiB
Go
// Copyright 2022 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package cpu
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import (
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"os"
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"runtime"
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"sync"
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"time"
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sigar "github.com/cloudfoundry/gosigar"
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"github.com/pingcap/failpoint"
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"github.com/pingcap/log"
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"github.com/pingcap/tidb/pkg/metrics"
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"github.com/pingcap/tidb/pkg/util/cgroup"
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"github.com/pingcap/tidb/pkg/util/mathutil"
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"go.uber.org/atomic"
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"go.uber.org/zap"
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)
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var cpuUsage atomic.Float64
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// If your kernel is lower than linux 4.7, you cannot get the cpu usage in the container.
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var unsupported atomic.Bool
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// GetCPUUsage returns the cpu usage of the current process.
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func GetCPUUsage() (float64, bool) {
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return cpuUsage.Load(), unsupported.Load()
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}
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// Observer is used to observe the cpu usage of the current process.
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type Observer struct {
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utime int64
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stime int64
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now int64
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exit chan struct{}
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cpu mathutil.ExponentialMovingAverage
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wg sync.WaitGroup
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}
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// NewCPUObserver returns a cpu observer.
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func NewCPUObserver() *Observer {
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return &Observer{
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exit: make(chan struct{}),
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now: time.Now().UnixNano(),
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cpu: *mathutil.NewExponentialMovingAverage(0.95, 10),
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}
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}
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// Start starts the cpu observer.
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func (c *Observer) Start() {
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_, err := cgroup.GetCgroupCPU()
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if err != nil {
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unsupported.Store(true)
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log.Error("GetCgroupCPU", zap.Error(err))
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return
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}
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c.wg.Add(1)
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go func() {
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ticker := time.NewTicker(100 * time.Millisecond)
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defer func() {
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ticker.Stop()
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c.wg.Done()
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}()
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for {
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select {
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case <-ticker.C:
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curr := c.observe()
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c.cpu.Add(curr)
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cpuUsage.Store(c.cpu.Get())
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metrics.EMACPUUsageGauge.Set(c.cpu.Get())
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case <-c.exit:
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return
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}
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}
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}()
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}
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// Stop stops the cpu observer.
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func (c *Observer) Stop() {
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close(c.exit)
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c.wg.Wait()
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}
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func (c *Observer) observe() float64 {
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user, sys, err := getCPUTime()
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if err != nil {
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log.Error("getCPUTime", zap.Error(err))
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}
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cgroupCPU, _ := cgroup.GetCgroupCPU()
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cpuShare := cgroupCPU.CPUShares()
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now := time.Now().UnixNano()
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dur := float64(now - c.now)
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utime := user * 1e6
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stime := sys * 1e6
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urate := float64(utime-c.utime) / dur
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srate := float64(stime-c.stime) / dur
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c.now = now
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c.utime = utime
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c.stime = stime
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return (srate + urate) / cpuShare
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}
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// getCPUTime returns the cumulative user/system time (in ms) since the process start.
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func getCPUTime() (userTimeMillis, sysTimeMillis int64, err error) {
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pid := os.Getpid()
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cpuTime := sigar.ProcTime{}
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if err := cpuTime.Get(pid); err != nil {
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return 0, 0, err
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}
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return int64(cpuTime.User), int64(cpuTime.Sys), nil
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}
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// GetCPUCount returns the number of logical CPUs usable by the current process.
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func GetCPUCount() int {
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failpoint.Inject("mockNumCpu", func(val failpoint.Value) {
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failpoint.Return(val.(int))
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})
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return runtime.GOMAXPROCS(0)
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}
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