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feat: allow setting of exporter process priority (#1488)
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breed808 committed May 17, 2024
1 parent b2ab542 commit eeaefba
Showing 1 changed file with 44 additions and 0 deletions.
44 changes: 44 additions & 0 deletions exporter.go
Original file line number Diff line number Diff line change
Expand Up @@ -31,8 +31,12 @@ import (
"github.com/prometheus/common/version"
"github.com/prometheus/exporter-toolkit/web"
webflag "github.com/prometheus/exporter-toolkit/web/kingpinflag"
"golang.org/x/sys/windows"
)

// https://learn.microsoft.com/en-us/windows/win32/procthread/process-security-and-access-rights
const PROCESS_ALL_ACCESS = windows.STANDARD_RIGHTS_REQUIRED | windows.SYNCHRONIZE | windows.SPECIFIC_RIGHTS_ALL

// Same struct prometheus uses for their /version endpoint.
// Separate copy to avoid pulling all of prometheus as a dependency
type prometheusVersion struct {
Expand All @@ -44,6 +48,32 @@ type prometheusVersion struct {
GoVersion string `json:"goVersion"`
}

// Mapping of priority names to uin32 values required by windows.SetPriorityClass
var priorityStringToInt = map[string]uint32{
"realtime": windows.REALTIME_PRIORITY_CLASS,
"high": windows.HIGH_PRIORITY_CLASS,
"abovenormal": windows.ABOVE_NORMAL_PRIORITY_CLASS,
"normal": windows.NORMAL_PRIORITY_CLASS,
"belownormal": windows.BELOW_NORMAL_PRIORITY_CLASS,
"low": windows.IDLE_PRIORITY_CLASS,
}

func setPriorityWindows(pid int, priority uint32) error {
handle, err := windows.OpenProcess(PROCESS_ALL_ACCESS, false, uint32(pid))
if err != nil {
return err
}
//nolint:errcheck
defer windows.CloseHandle(handle) // Technically this can fail, but we ignore it

err = windows.SetPriorityClass(handle, priority)
if err != nil {
return err
}

return nil
}

func main() {
app := kingpin.New("windows_exporter", "A metrics collector for Windows.")
var (
Expand Down Expand Up @@ -84,6 +114,10 @@ func main() {
"debug.enabled",
"If true, windows_exporter will expose debug endpoints under /debug/pprof.",
).Default("false").Bool()
processPriority = app.Flag(
"process.priority",
"Priority of the exporter process. Higher priorities may improve exporter responsiveness during periods of system load. Can be one of [\"realtime\", \"high\", \"abovenormal\", \"normal\", \"belownormal\", \"low\"]",
).Default("normal").String()
)

winlogConfig := &winlog.Config{}
Expand Down Expand Up @@ -145,6 +179,16 @@ func main() {
return
}

// Only set process priority if a non-default and valid value has been set
if *processPriority != "normal" && priorityStringToInt[*processPriority] != 0 {
_ = level.Debug(logger).Log("msg", "setting process priority to "+*processPriority)
err = setPriorityWindows(os.Getpid(), priorityStringToInt[*processPriority])
if err != nil {
_ = level.Error(logger).Log("msg", "failed to set process priority", "err", err)
os.Exit(1)
}
}

if err = wmi.InitWbem(logger); err != nil {
_ = level.Error(logger).Log("err", err)
os.Exit(1)
Expand Down

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