+// Copyright (C) The Arvados Authors. All rights reserved.
+//
+// SPDX-License-Identifier: AGPL-3.0
+
+// Package crunchstat reports resource usage (CPU, memory, disk,
+// network) for a cgroup.
package crunchstat
import (
"time"
)
-// This magically allows us to look up user_hz via _SC_CLK_TCK:
+// This magically allows us to look up userHz via _SC_CLK_TCK:
/*
#include <unistd.h>
// log.Logger.
type Reporter struct {
// CID of the container to monitor. If empty, read the CID
- // from CIDFile.
+ // from CIDFile (first waiting until a non-empty file appears
+ // at CIDFile). If CIDFile is also empty, report host
+ // statistics.
CID string
- // Where cgroup special files live on this system
- CgroupRoot string
- CgroupParent string
- // Path to a file we can read CID from. If CIDFile is empty or
- // nonexistent, wait for it to appear.
+
+ // Path to a file we can read CID from.
CIDFile string
- // Interval between samples
- Poll time.Duration
+ // Where cgroup accounting files live on this system, e.g.,
+ // "/sys/fs/cgroup".
+ CgroupRoot string
- // Where to write statistics.
+ // Parent cgroup, e.g., "docker".
+ CgroupParent string
+
+ // Interval between samples. Must be positive.
+ PollPeriod time.Duration
+
+ // Where to write statistics. Must not be nil.
Logger *log.Logger
reportedStatFile map[string]string
- lastNetSample map[string]IoSample
- lastDiskSample map[string]IoSample
- lastCPUSample CpuSample
+ lastNetSample map[string]ioSample
+ lastDiskSample map[string]ioSample
+ lastCPUSample cpuSample
- done chan struct{}
+ done chan struct{} // closed when we should stop reporting
+ flushed chan struct{} // closed when we have made our last report
}
-// Wait (if necessary) for the CID to appear in CIDFile, then start
-// reporting statistics.
+// Start starts monitoring in a new goroutine, and returns
+// immediately.
//
-// Start should not be called more than once on a Reporter.
+// The monitoring goroutine waits for a non-empty CIDFile to appear
+// (unless CID is non-empty). Then it waits for the accounting files
+// to appear for the monitored container. Then it collects and reports
+// statistics until Stop is called.
//
-// Public data fields should not be changed after calling Start.
+// Callers should not call Start more than once.
+//
+// Callers should not modify public data fields after calling Start.
func (r *Reporter) Start() {
r.done = make(chan struct{})
+ r.flushed = make(chan struct{})
go r.run()
}
-// Stop reporting statistics. Do not call more than once, or before
-// calling Start.
+// Stop reporting. Do not call more than once, or before calling
+// Start.
//
// Nothing will be logged after Stop returns.
func (r *Reporter) Stop() {
close(r.done)
+ <-r.flushed
}
-func (r *Reporter) readAllOrWarn(in *os.File) ([]byte, error) {
+func (r *Reporter) readAllOrWarn(in io.Reader) ([]byte, error) {
content, err := ioutil.ReadAll(in)
if err != nil {
r.Logger.Print(err)
}
// Open the cgroup stats file in /sys/fs corresponding to the target
-// cgroup, and return an *os.File. If no stats file is available,
+// cgroup, and return an io.ReadCloser. If no stats file is available,
// return nil.
//
+// Log the file that was opened, if it isn't the same file opened on
+// the last openStatFile for this stat.
+//
+// Log "not available" if no file is found and either this stat has
+// been available in the past, or verbose==true.
+//
// TODO: Instead of trying all options, choose a process in the
// container, and read /proc/PID/cgroup to determine the appropriate
// cgroup root for the given statgroup. (This will avoid falling back
// to host-level stats during container setup and teardown.)
-func (r *Reporter) openStatFile(statgroup string, stat string) (*os.File, error) {
+func (r *Reporter) openStatFile(statgroup, stat string, verbose bool) (io.ReadCloser, error) {
var paths []string
if r.CID != "" {
// Collect container's stats
path = ""
}
}
- if pathWas, ok := r.reportedStatFile[stat]; !ok || pathWas != path {
+ if pathWas := r.reportedStatFile[stat]; pathWas != path {
// Log whenever we start using a new/different cgroup
// stat file for a given statistic. This typically
// happens 1 to 3 times per statistic, depending on
// whether we happen to collect stats [a] before any
// processes have been created in the container and
// [b] after all contained processes have exited.
- if path == "" {
+ if path == "" && verbose {
r.Logger.Printf("notice: stats not available: stat %s, statgroup %s, cid %s, parent %s, root %s\n", stat, statgroup, r.CID, r.CgroupParent, r.CgroupRoot)
- } else if ok {
+ } else if pathWas != "" {
r.Logger.Printf("notice: stats moved from %s to %s\n", r.reportedStatFile[stat], path)
} else {
r.Logger.Printf("notice: reading stats from %s\n", path)
}
func (r *Reporter) getContainerNetStats() (io.Reader, error) {
- procsFile, err := r.openStatFile("cpuacct", "cgroup.procs")
+ procsFile, err := r.openStatFile("cpuacct", "cgroup.procs", true)
if err != nil {
return nil, err
}
return nil, errors.New("Could not read stats for any proc in container")
}
-type IoSample struct {
+type ioSample struct {
sampleTime time.Time
txBytes int64
rxBytes int64
}
-func (r *Reporter) DoBlkIoStats() {
- c, err := r.openStatFile("blkio", "blkio.io_service_bytes")
+func (r *Reporter) doBlkIOStats() {
+ c, err := r.openStatFile("blkio", "blkio.io_service_bytes", true)
if err != nil {
return
}
defer c.Close()
b := bufio.NewScanner(c)
var sampleTime = time.Now()
- newSamples := make(map[string]IoSample)
+ newSamples := make(map[string]ioSample)
for b.Scan() {
var device, op string
var val int64
if _, err := fmt.Sscanf(string(b.Text()), "%s %s %d", &device, &op, &val); err != nil {
continue
}
- var thisSample IoSample
+ var thisSample ioSample
var ok bool
if thisSample, ok = newSamples[device]; !ok {
- thisSample = IoSample{sampleTime, -1, -1}
+ thisSample = ioSample{sampleTime, -1, -1}
}
switch op {
case "Read":
}
}
-type MemSample struct {
+type memSample struct {
sampleTime time.Time
memStat map[string]int64
}
-func (r *Reporter) DoMemoryStats() {
- c, err := r.openStatFile("memory", "memory.stat")
+func (r *Reporter) doMemoryStats() {
+ c, err := r.openStatFile("memory", "memory.stat", true)
if err != nil {
return
}
defer c.Close()
b := bufio.NewScanner(c)
- thisSample := MemSample{time.Now(), make(map[string]int64)}
+ thisSample := memSample{time.Now(), make(map[string]int64)}
wantStats := [...]string{"cache", "swap", "pgmajfault", "rss"}
for b.Scan() {
var stat string
r.Logger.Printf("mem%s\n", outstat.String())
}
-func (r *Reporter) DoNetworkStats() {
+func (r *Reporter) doNetworkStats() {
sampleTime := time.Now()
stats, err := r.getContainerNetStats()
if err != nil {
if rx, err = strconv.ParseInt(words[1], 10, 64); err != nil {
continue
}
- nextSample := IoSample{}
+ nextSample := ioSample{}
nextSample.sampleTime = sampleTime
nextSample.txBytes = tx
nextSample.rxBytes = rx
}
}
-type CpuSample struct {
+type cpuSample struct {
hasData bool // to distinguish the zero value from real data
sampleTime time.Time
user float64
// Return the number of CPUs available in the container. Return 0 if
// we can't figure out the real number of CPUs.
-func (r *Reporter) GetCpuCount() int64 {
- cpusetFile, err := r.openStatFile("cpuset", "cpuset.cpus")
+func (r *Reporter) getCPUCount() int64 {
+ cpusetFile, err := r.openStatFile("cpuset", "cpuset.cpus", true)
if err != nil {
return 0
}
defer cpusetFile.Close()
b, err := r.readAllOrWarn(cpusetFile)
+ if err != nil {
+ return 0
+ }
sp := strings.Split(string(b), ",")
cpus := int64(0)
for _, v := range sp {
if n == 2 {
cpus += (max - min) + 1
} else {
- cpus += 1
+ cpus++
}
}
return cpus
}
-func (r *Reporter) DoCpuStats() {
- statFile, err := r.openStatFile("cpuacct", "cpuacct.stat")
+func (r *Reporter) doCPUStats() {
+ statFile, err := r.openStatFile("cpuacct", "cpuacct.stat", true)
if err != nil {
return
}
return
}
- nextSample := CpuSample{true, time.Now(), 0, 0, r.GetCpuCount()}
var userTicks, sysTicks int64
fmt.Sscanf(string(b), "user %d\nsystem %d", &userTicks, &sysTicks)
- user_hz := float64(C.sysconf(C._SC_CLK_TCK))
- nextSample.user = float64(userTicks) / user_hz
- nextSample.sys = float64(sysTicks) / user_hz
+ userHz := float64(C.sysconf(C._SC_CLK_TCK))
+ nextSample := cpuSample{
+ hasData: true,
+ sampleTime: time.Now(),
+ user: float64(userTicks) / userHz,
+ sys: float64(sysTicks) / userHz,
+ cpus: r.getCPUCount(),
+ }
delta := ""
if r.lastCPUSample.hasData {
r.lastCPUSample = nextSample
}
-// Report stats periodically until someone closes or sends to r.done.
+// Report stats periodically until we learn (via r.done) that someone
+// called Stop.
func (r *Reporter) run() {
- if !r.waitForCIDFile() {
+ defer close(r.flushed)
+
+ r.reportedStatFile = make(map[string]string)
+
+ if !r.waitForCIDFile() || !r.waitForCgroup() {
return
}
- r.reportedStatFile = make(map[string]string)
- r.lastNetSample = make(map[string]IoSample)
- r.lastDiskSample = make(map[string]IoSample)
+ r.lastNetSample = make(map[string]ioSample)
+ r.lastDiskSample = make(map[string]ioSample)
- ticker := time.NewTicker(r.Poll)
+ ticker := time.NewTicker(r.PollPeriod)
for {
- r.DoMemoryStats()
- r.DoCpuStats()
- r.DoBlkIoStats()
- r.DoNetworkStats()
+ r.doMemoryStats()
+ r.doCPUStats()
+ r.doBlkIOStats()
+ r.doNetworkStats()
select {
case <-r.done:
return
}
// If CID is empty, wait for it to appear in CIDFile. Return true if
-// we get it before someone calls Stop().
+// we get it before we learn (via r.done) that someone called Stop.
func (r *Reporter) waitForCIDFile() bool {
- if r.CID != "" {
+ if r.CID != "" || r.CIDFile == "" {
return true
}
}
}
}
+
+// Wait for the cgroup stats files to appear in cgroup_root. Return
+// true if they appear before r.done indicates someone called Stop. If
+// they don't appear within one poll interval, log a warning and keep
+// waiting.
+func (r *Reporter) waitForCgroup() bool {
+ ticker := time.NewTicker(100 * time.Millisecond)
+ defer ticker.Stop()
+ warningTimer := time.After(r.PollPeriod)
+ for {
+ c, err := r.openStatFile("cpuacct", "cgroup.procs", false)
+ if err == nil {
+ c.Close()
+ return true
+ }
+ select {
+ case <-ticker.C:
+ case <-warningTimer:
+ r.Logger.Printf("cgroup stats files have not appeared after %v (config error?) -- still waiting...", r.PollPeriod)
+ case <-r.done:
+ r.Logger.Printf("cgroup stats files never appeared for %v", r.CID)
+ return false
+ }
+ }
+}
projects / arvados.git / blobdiff