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// Copyright 2015 The Prometheus 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package prometheus
import (
type processCollector struct {
collectFn func(chan<- Metric)
pidFn func() (int, error)
reportErrors bool
cpuTotal *Desc
openFDs, maxFDs *Desc
vsize, maxVsize *Desc
rss *Desc
startTime *Desc
// ProcessCollectorOpts defines the behavior of a process metrics collector
// created with NewProcessCollector.
type ProcessCollectorOpts struct {
// PidFn returns the PID of the process the collector collects metrics
// for. It is called upon each collection. By default, the PID of the
// current process is used, as determined on construction time by
// calling os.Getpid().
PidFn func() (int, error)
// If non-empty, each of the collected metrics is prefixed by the
// provided string and an underscore ("_").
Namespace string
// If true, any error encountered during collection is reported as an
// invalid metric (see NewInvalidMetric). Otherwise, errors are ignored
// and the collected metrics will be incomplete. (Possibly, no metrics
// will be collected at all.) While that's usually not desired, it is
// appropriate for the common "mix-in" of process metrics, where process
// metrics are nice to have, but failing to collect them should not
// disrupt the collection of the remaining metrics.
ReportErrors bool
// NewProcessCollector is the obsolete version of collectors.NewProcessCollector.
// See there for documentation.
// Deprecated: Use collectors.NewProcessCollector instead.
func NewProcessCollector(opts ProcessCollectorOpts) Collector {
ns := ""
if len(opts.Namespace) > 0 {
ns = opts.Namespace + "_"
c := &processCollector{
reportErrors: opts.ReportErrors,
cpuTotal: NewDesc(
"Total user and system CPU time spent in seconds.",
nil, nil,
openFDs: NewDesc(
"Number of open file descriptors.",
nil, nil,
maxFDs: NewDesc(
"Maximum number of open file descriptors.",
nil, nil,
vsize: NewDesc(
"Virtual memory size in bytes.",
nil, nil,
maxVsize: NewDesc(
"Maximum amount of virtual memory available in bytes.",
nil, nil,
rss: NewDesc(
"Resident memory size in bytes.",
nil, nil,
startTime: NewDesc(
"Start time of the process since unix epoch in seconds.",
nil, nil,
if opts.PidFn == nil {
pid := os.Getpid()
c.pidFn = func() (int, error) { return pid, nil }
} else {
c.pidFn = opts.PidFn
// Set up process metric collection if supported by the runtime.
if canCollectProcess() {
c.collectFn = c.processCollect
} else {
c.collectFn = func(ch chan<- Metric) {
c.reportError(ch, nil, errors.New("process metrics not supported on this platform"))
return c
// Describe returns all descriptions of the collector.
func (c *processCollector) Describe(ch chan<- *Desc) {
ch <- c.cpuTotal
ch <- c.openFDs
ch <- c.maxFDs
ch <- c.vsize
ch <- c.maxVsize
ch <- c.rss
ch <- c.startTime
// Collect returns the current state of all metrics of the collector.
func (c *processCollector) Collect(ch chan<- Metric) {
func (c *processCollector) reportError(ch chan<- Metric, desc *Desc, err error) {
if !c.reportErrors {
if desc == nil {
desc = NewInvalidDesc(err)
ch <- NewInvalidMetric(desc, err)
// NewPidFileFn returns a function that retrieves a pid from the specified file.
// It is meant to be used for the PidFn field in ProcessCollectorOpts.
func NewPidFileFn(pidFilePath string) func() (int, error) {
return func() (int, error) {
content, err := ioutil.ReadFile(pidFilePath)
if err != nil {
return 0, fmt.Errorf("can't read pid file %q: %+v", pidFilePath, err)
pid, err := strconv.Atoi(strings.TrimSpace(string(content)))
if err != nil {
return 0, fmt.Errorf("can't parse pid file %q: %+v", pidFilePath, err)
return pid, nil