package procfs import ( "bytes" "fmt" "io/ioutil" "os" ) // Originally, this USER_HZ value was dynamically retrieved via a sysconf call which // required cgo. However, that caused a lot of problems regarding // cross-compilation. Alternatives such as running a binary to determine the // value, or trying to derive it in some other way were all problematic. // After much research it was determined that USER_HZ is actually hardcoded to // 100 on all Go-supported platforms as of the time of this writing. This is // why we decided to hardcode it here as well. It is not impossible that there // could be systems with exceptions, but they should be very exotic edge cases, // and in that case, the worst outcome will be two misreported metrics. // // See also the following discussions: // // - https://github.com/prometheus/node_exporter/issues/52 // - https://github.com/prometheus/procfs/pull/2 // - http://stackoverflow.com/questions/17410841/how-does-user-hz-solve-the-jiffy-scaling-issue const userHZ = 100 // ProcStat provides status information about the process, // read from /proc/[pid]/stat. type ProcStat struct { // The process ID. PID int // The filename of the executable. Comm string // The process state. State string // The PID of the parent of this process. PPID int // The process group ID of the process. PGRP int // The session ID of the process. Session int // The controlling terminal of the process. TTY int // The ID of the foreground process group of the controlling terminal of // the process. TPGID int // The kernel flags word of the process. Flags uint // The number of minor faults the process has made which have not required // loading a memory page from disk. MinFlt uint // The number of minor faults that the process's waited-for children have // made. CMinFlt uint // The number of major faults the process has made which have required // loading a memory page from disk. MajFlt uint // The number of major faults that the process's waited-for children have // made. CMajFlt uint // Amount of time that this process has been scheduled in user mode, // measured in clock ticks. UTime uint // Amount of time that this process has been scheduled in kernel mode, // measured in clock ticks. STime uint // Amount of time that this process's waited-for children have been // scheduled in user mode, measured in clock ticks. CUTime uint // Amount of time that this process's waited-for children have been // scheduled in kernel mode, measured in clock ticks. CSTime uint // For processes running a real-time scheduling policy, this is the negated // scheduling priority, minus one. Priority int // The nice value, a value in the range 19 (low priority) to -20 (high // priority). Nice int // Number of threads in this process. NumThreads int // The time the process started after system boot, the value is expressed // in clock ticks. Starttime uint64 // Virtual memory size in bytes. VSize int // Resident set size in pages. RSS int fs FS } // NewStat returns the current status information of the process. func (p Proc) NewStat() (ProcStat, error) { f, err := p.open("stat") if err != nil { return ProcStat{}, err } defer f.Close() data, err := ioutil.ReadAll(f) if err != nil { return ProcStat{}, err } var ( ignore int s = ProcStat{PID: p.PID, fs: p.fs} l = bytes.Index(data, []byte("(")) r = bytes.LastIndex(data, []byte(")")) ) if l < 0 || r < 0 { return ProcStat{}, fmt.Errorf( "unexpected format, couldn't extract comm: %s", data, ) } s.Comm = string(data[l+1 : r]) _, err = fmt.Fscan( bytes.NewBuffer(data[r+2:]), &s.State, &s.PPID, &s.PGRP, &s.Session, &s.TTY, &s.TPGID, &s.Flags, &s.MinFlt, &s.CMinFlt, &s.MajFlt, &s.CMajFlt, &s.UTime, &s.STime, &s.CUTime, &s.CSTime, &s.Priority, &s.Nice, &s.NumThreads, &ignore, &s.Starttime, &s.VSize, &s.RSS, ) if err != nil { return ProcStat{}, err } return s, nil } // VirtualMemory returns the virtual memory size in bytes. func (s ProcStat) VirtualMemory() int { return s.VSize } // ResidentMemory returns the resident memory size in bytes. func (s ProcStat) ResidentMemory() int { return s.RSS * os.Getpagesize() } // StartTime returns the unix timestamp of the process in seconds. func (s ProcStat) StartTime() (float64, error) { stat, err := s.fs.NewStat() if err != nil { return 0, err } return float64(stat.BootTime) + (float64(s.Starttime) / userHZ), nil } // CPUTime returns the total CPU user and system time in seconds. func (s ProcStat) CPUTime() float64 { return float64(s.UTime+s.STime) / userHZ }