libcontainer/system/proc: Add Stat_t.State
And Stat_t.PID and Stat_t.Name while we're at it. Then use the new .State property in runType to distinguish between running and zombie/dead processes, since kill(2) does not [1]. With this change we no longer claim Running status for zombie/dead processes. I've also removed the kill(2) call from runType. It was originally added in13841ef3(new-api: return the Running state only if the init process is alive, 2014-12-23), but we've been accessing /proc/[pid]/stat since14e95b2a(Make state detection precise, 2016-07-05, #930), and with the /stat access the kill(2) check is redundant. I also don't see much point to the previously-separate doesInitProcessExist, so I've inlined that logic in runType. It would be nice to distinguish between "/proc/[pid]/stat doesn't exist" and errors parsing its contents, but I've skipped that for the moment. The Running -> Stopped change in checkpoint_test.go is because the post-checkpoint process is a zombie, and with this commit zombie processes are Stopped (and no longer Running). [1]: https://github.com/opencontainers/runc/pull/1483#issuecomment-307527789 Signed-off-by: W. Trevor King <wking@tremily.us>
This commit is contained in:
W. Trevor King
parent
75d98b26b7
commit
2bea4c897e
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@ -1365,40 +1365,17 @@ func (c *linuxContainer) refreshState() error {
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return c.state.transition(&stoppedState{c: c})
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}
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// doesInitProcessExist checks if the init process is still the same process
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// as the initial one, it could happen that the original process has exited
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// and a new process has been created with the same pid, in this case, the
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// container would already be stopped.
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func (c *linuxContainer) doesInitProcessExist(initPid int) (bool, error) {
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stat, err := system.Stat(initPid)
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if err != nil {
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return false, newSystemErrorWithCausef(err, "getting init process %d status", initPid)
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}
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if c.initProcessStartTime != stat.StartTime {
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return false, nil
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}
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return true, nil
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}
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func (c *linuxContainer) runType() (Status, error) {
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if c.initProcess == nil {
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return Stopped, nil
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}
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pid := c.initProcess.pid()
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// return Running if the init process is alive
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if err := unix.Kill(pid, 0); err != nil {
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if err == unix.ESRCH {
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// It means the process does not exist anymore, could happen when the
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// process exited just when we call the function, we should not return
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// error in this case.
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return Stopped, nil
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}
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return Stopped, newSystemErrorWithCausef(err, "sending signal 0 to pid %d", pid)
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stat, err := system.Stat(pid)
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if err != nil {
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return Stopped, nil
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}
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// check if the process is still the original init process.
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exist, err := c.doesInitProcessExist(pid)
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if !exist || err != nil {
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return Stopped, err
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if stat.StartTime != c.initProcessStartTime || stat.State == system.Zombie || stat.State == system.Dead {
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return Stopped, nil
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}
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// We'll create exec fifo and blocking on it after container is created,
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// and delete it after start container.
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@ -180,7 +180,7 @@ func testCheckpoint(t *testing.T, userns bool) {
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t.Fatal(err)
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}
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if state != libcontainer.Running {
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if state != libcontainer.Stopped {
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t.Fatal("Unexpected state checkpoint: ", state)
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}
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@ -8,9 +8,55 @@ import (
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"strings"
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)
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// State is the status of a process.
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type State rune
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const ( // Only values for Linux 3.14 and later are listed here
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Dead State = 'X'
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DiskSleep State = 'D'
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Running State = 'R'
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Sleeping State = 'S'
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Stopped State = 'T'
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TracingStop State = 't'
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Zombie State = 'Z'
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)
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// String forms of the state from proc(5)'s documentation for
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// /proc/[pid]/status' "State" field.
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func (s State) String() string {
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switch s {
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case Dead:
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return "dead"
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case DiskSleep:
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return "disk sleep"
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case Running:
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return "running"
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case Sleeping:
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return "sleeping"
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case Stopped:
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return "stopped"
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case TracingStop:
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return "tracing stop"
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case Zombie:
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return "zombie"
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default:
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return fmt.Sprintf("unknown (%c)", s)
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}
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}
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// Stat_t represents the information from /proc/[pid]/stat, as
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// described in proc(5).
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// described in proc(5) with names based on the /proc/[pid]/status
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// fields.
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type Stat_t struct {
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// PID is the process ID.
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PID uint
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// Name is the command run by the process.
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Name string
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// State is the state of the process.
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State State
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// StartTime is the number of clock ticks after system boot (since
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// Linux 2.6).
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StartTime uint64
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@ -22,9 +68,7 @@ func Stat(pid int) (stat Stat_t, err error) {
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if err != nil {
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return stat, err
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}
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data := string(bytes)
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stat.StartTime, err = parseStartTime(data)
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return stat, err
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return parseStat(string(bytes))
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}
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// GetProcessStartTime is deprecated. Use Stat(pid) and
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@ -37,30 +81,33 @@ func GetProcessStartTime(pid int) (string, error) {
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return fmt.Sprintf("%d", stat.StartTime), nil
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}
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func parseStartTime(stat string) (uint64, error) {
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// the starttime is located at pos 22
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// from the man page
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//
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// starttime %llu (was %lu before Linux 2.6)
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// (22) The time the process started after system boot. In kernels before Linux 2.6, this
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// value was expressed in jiffies. Since Linux 2.6, the value is expressed in clock ticks
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// (divide by sysconf(_SC_CLK_TCK)).
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//
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// NOTE:
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// pos 2 could contain space and is inside `(` and `)`:
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// (2) comm %s
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// The filename of the executable, in parentheses.
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// This is visible whether or not the executable is
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// swapped out.
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//
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// the following is an example:
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func parseStat(data string) (stat Stat_t, err error) {
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// From proc(5), field 2 could contain space and is inside `(` and `)`.
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// The following is an example:
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// 89653 (gunicorn: maste) S 89630 89653 89653 0 -1 4194560 29689 28896 0 3 146 32 76 19 20 0 1 0 2971844 52965376 3920 18446744073709551615 1 1 0 0 0 0 0 16781312 137447943 0 0 0 17 1 0 0 0 0 0 0 0 0 0 0 0 0 0
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i := strings.LastIndex(data, ")")
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if i <= 2 || i >= len(data)-1 {
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return stat, fmt.Errorf("invalid stat data: %q", data)
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}
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// get parts after last `)`:
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s := strings.Split(stat, ")")
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parts := strings.Split(strings.TrimSpace(s[len(s)-1]), " ")
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startTimeString := parts[22-3] // starts at 3 (after the filename pos `2`)
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var startTime uint64
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fmt.Sscanf(startTimeString, "%d", &startTime)
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return startTime, nil
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parts := strings.SplitN(data[:i], "(", 2)
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if len(parts) != 2 {
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return stat, fmt.Errorf("invalid stat data: %q", data)
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}
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stat.Name = parts[1]
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_, err = fmt.Sscanf(parts[0], "%d", &stat.PID)
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if err != nil {
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return stat, err
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}
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// parts indexes should be offset by 3 from the field number given
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// proc(5), because parts is zero-indexed and we've removed fields
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// one (PID) and two (Name) in the paren-split.
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parts = strings.Split(data[i+2:], " ")
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var state int
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fmt.Sscanf(parts[3-3], "%c", &state)
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stat.State = State(state)
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fmt.Sscanf(parts[22-3], "%d", &stat.StartTime)
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return stat, nil
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}
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@ -3,18 +3,43 @@ package system
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import "testing"
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func TestParseStartTime(t *testing.T) {
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data := map[string]uint64{
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"4902 (gunicorn: maste) S 4885 4902 4902 0 -1 4194560 29683 29929 61 83 78 16 96 17 20 0 1 0 9126532 52965376 1903 18446744073709551615 4194304 7461796 140733928751520 140733928698072 139816984959091 0 0 16781312 137447943 1 0 0 17 3 0 0 9 0 0 9559488 10071156 33050624 140733928758775 140733928758945 140733928758945 140733928759264 0": 9126532,
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"9534 (cat) R 9323 9534 9323 34828 9534 4194304 95 0 0 0 0 0 0 0 20 0 1 0 9214966 7626752 168 18446744073709551615 4194304 4240332 140732237651568 140732237650920 140570710391216 0 0 0 0 0 0 0 17 1 0 0 0 0 0 6340112 6341364 21553152 140732237653865 140732237653885 140732237653885 140732237656047 0": 9214966,
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"24767 (irq/44-mei_me) S 2 0 0 0 -1 2129984 0 0 0 0 0 0 0 0 -51 0 1 0 8722075 0 0 18446744073709551615 0 0 0 0 0 0 0 2147483647 0 0 0 0 17 1 50 1 0 0 0 0 0 0 0 0 0 0 0": 8722075,
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data := map[string]Stat_t{
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"4902 (gunicorn: maste) S 4885 4902 4902 0 -1 4194560 29683 29929 61 83 78 16 96 17 20 0 1 0 9126532 52965376 1903 18446744073709551615 4194304 7461796 140733928751520 140733928698072 139816984959091 0 0 16781312 137447943 1 0 0 17 3 0 0 9 0 0 9559488 10071156 33050624 140733928758775 140733928758945 140733928758945 140733928759264 0": {
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PID: 4902,
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Name: "gunicorn: maste",
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State: 'S',
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StartTime: 9126532,
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},
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"9534 (cat) R 9323 9534 9323 34828 9534 4194304 95 0 0 0 0 0 0 0 20 0 1 0 9214966 7626752 168 18446744073709551615 4194304 4240332 140732237651568 140732237650920 140570710391216 0 0 0 0 0 0 0 17 1 0 0 0 0 0 6340112 6341364 21553152 140732237653865 140732237653885 140732237653885 140732237656047 0": {
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PID: 9534,
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Name: "cat",
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State: 'R',
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StartTime: 9214966,
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},
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"24767 (irq/44-mei_me) S 2 0 0 0 -1 2129984 0 0 0 0 0 0 0 0 -51 0 1 0 8722075 0 0 18446744073709551615 0 0 0 0 0 0 0 2147483647 0 0 0 0 17 1 50 1 0 0 0 0 0 0 0 0 0 0 0": {
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PID: 24767,
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Name: "irq/44-mei_me",
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State: 'S',
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StartTime: 8722075,
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},
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}
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for line, startTime := range data {
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st, err := parseStartTime(line)
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for line, expected := range data {
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st, err := parseStat(line)
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if err != nil {
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t.Fatal(err)
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}
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if startTime != st {
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t.Fatalf("expected start time %q but received %q", startTime, st)
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if st.PID != expected.PID {
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t.Fatalf("expected PID %q but received %q", expected.PID, st.PID)
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}
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if st.State != expected.State {
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t.Fatalf("expected state %q but received %q", expected.State, st.State)
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}
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if st.Name != expected.Name {
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t.Fatalf("expected name %q but received %q", expected.Name, st.Name)
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}
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if st.StartTime != expected.StartTime {
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t.Fatalf("expected start time %q but received %q", expected.StartTime, st.StartTime)
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}
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}
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}
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