[systemd-devel] unit been dead before been running
aleivag
aleivag at gmail.com
Wed Mar 13 18:40:52 UTC 2019
Hi all:
Sorry to bring this up again... here is what i plan to do, i'm just asking
if this make sense.
(the context is that i start a transient unit, and pass tty fd, and i need
to know when the unit is dead, so i can close my fds)
`systemd1.Manager.StartTransientUnit` returns a job in the form of
`/org/freedesktop/systemd1/job/<job_id>`, so i'm just going to ignore all
messages that comes with that Job. Because those comes when the unit is
starting up.. the final `dead` of `failed` message comes with Job (0, '/')..
do that make sense?
Thanks!
Alvaro Leiva
On Mon, Feb 18, 2019 at 1:46 PM aleivag <aleivag at gmail.com> wrote:
>
> Hi All:
>
> i notice a change of behaviour that broke a couple of my scripts between
> v239 and v240, and wanted to know that maybe i was always assuming the
> wrong thing, so here it goes:
>
> so i subscribe to
>
> "type='signal',"
> "sender='org.freedesktop.systemd1',"
> "path='/org/freedesktop/systemd1/unit/myu_2eservice',"
> "interface='org.freedesktop.DBus.Properties',"
> "member='PropertiesChanged'"
>
> on the bus, and then i start a transient unit like `systemd-run --pty
> --unit myu.service /bin/bash` .
>
> to do the subscribe to that event i use the following script, (its
> definitely not important the script i use but just show you for
> completeness),
>
> ```
> #!/usr/bin/python3
>
> from pprint import pprint
> import pystemd
> from pystemd.dbuslib import DBus
>
> with DBus() as bus, pystemd.DBus.Manager(bus=bus, _autoload=True) as man:
> mstr = (
> "type='signal',"
> "sender='org.freedesktop.systemd1',"
> "path='/org/freedesktop/systemd1/unit/myu_2eservice',"
> "interface='org.freedesktop.DBus.Properties',"
> "member='PropertiesChanged'"
> ).encode()
> man.Monitoring.BecomeMonitor([mstr], 0)
> while True:
> bus.wait(1000)
> m = bus.process()
> if m.is_empty():
> continue
>
> m.process_reply(False)
> if m.get_path() == b'/org/freedesktop/systemd1/unit/myu_2eservice':
> pprint(m.body)
> ```
>
>
> on systemd v239 and bellow before the unit is active i got only 2
> messages, one `org.freedesktop.systemd1.Service` and one on
> `org.freedesktop.systemd1.Unit`. the second one notify me that the
> "SubState" is "running". when the unit ends, i get 2 messages also, and the
> last one is to tell me that the "SubState" is "dead"
>
> on v240 on the other part, before the unit ready, i get 4 messages, one
> on `org.freedesktop.systemd1.Service` -> `org.freedesktop.systemd1.Unit` ->
> `org.freedesktop.systemd1.Service` -> `org.freedesktop.systemd1.Unit`,
> where the Unit ones the substate first is "dead" and then is "running", on
> deactivating, the messages are the same between 239 and 240.
>
> so i used to tell that the unit had finished, by inspecting the messages
> on the bus, and then looking for SubState to be any of ("exited", "failed",
> "dead"), but i cant do that now.
>
> at the end of the email i copy the dumps on the 2 versions, but my
> questions are:
>
> 1.- Is this change in behaviour, intended, or a side effect of something
> else?
> 2.- was what i was doing the best way to decide if a transient unit has
> finished? i'm super temped to instead check when the
> `org.freedesktop.systemd1.Service.MainPID == 0` i think its the best idea,
> but maybe you guys have one that is better.
>
> thanks guys!!
>
> now i paste the messages:
>
> on v239
>
> on start
> [b'org.freedesktop.systemd1.Service',
> {b'ControlPID': 0,
> b'ExecMainCode': 0,
> b'ExecMainExitTimestamp': 0,
> b'ExecMainExitTimestampMonotonic': 0,
> b'ExecMainPID': 18328,
> b'ExecMainStartTimestamp': 1550516822984246,
> b'ExecMainStartTimestampMonotonic': 41004687391,
> b'ExecMainStatus': 0,
> b'GID': 4294967295,
> b'MainPID': 18328,
> b'NRestarts': 0,
> b'Result': b'success',
> b'StatusErrno': 0,
> b'StatusText': b'',
> b'UID': 4294967295,
> b'USBFunctionDescriptors': b'',
> b'USBFunctionStrings': b''},
> [b'ExecStartPre',
> b'ExecStart',
> b'ExecStartPost',
> b'ExecReload',
> b'ExecStop',
> b'ExecStopPost']]
> [b'org.freedesktop.systemd1.Unit',
> {b'ActiveEnterTimestamp': 1550516822984291,
> b'ActiveEnterTimestampMonotonic': 41004687437,
> b'ActiveExitTimestamp': 0,
> b'ActiveExitTimestampMonotonic': 0,
> b'ActiveState': b'active',
> b'AssertResult': True,
> b'AssertTimestamp': 1550516822983511,
> b'AssertTimestampMonotonic': 41004686656,
> b'ConditionResult': True,
> b'ConditionTimestamp': 1550516822983509,
> b'ConditionTimestampMonotonic': 41004686655,
> b'InactiveEnterTimestamp': 0,
> b'InactiveEnterTimestampMonotonic': 0,
> b'InactiveExitTimestamp': 1550516822984291,
> b'InactiveExitTimestampMonotonic': 41004687437,
> b'Job': (0, b'/'),
> b'StateChangeTimestamp': 1550516822984291,
> b'StateChangeTimestampMonotonic': 41004687437,
> b'SubState': b'running'},
> []]
>
> on end
>
> [b'org.freedesktop.systemd1.Service',
> {b'ControlPID': 0,
> b'ExecMainCode': 1,
> b'ExecMainExitTimestamp': 1550516877103509,
> b'ExecMainExitTimestampMonotonic': 41058806656,
> b'ExecMainPID': 18328,
> b'ExecMainStartTimestamp': 1550516822984246,
> b'ExecMainStartTimestampMonotonic': 41004687391,
> b'ExecMainStatus': 0,
> b'GID': 4294967295,
> b'MainPID': 0,
> b'NRestarts': 0,
> b'Result': b'success',
> b'StatusErrno': 0,
> b'StatusText': b'',
> b'UID': 4294967295,
> b'USBFunctionDescriptors': b'',
> b'USBFunctionStrings': b''},
> [b'ExecStartPre',
> b'ExecStart',
> b'ExecStartPost',
> b'ExecReload',
> b'ExecStop',
> b'ExecStopPost']]
> [b'org.freedesktop.systemd1.Unit',
> {b'ActiveEnterTimestamp': 1550516822984291,
> b'ActiveEnterTimestampMonotonic': 41004687437,
> b'ActiveExitTimestamp': 1550516877103599,
> b'ActiveExitTimestampMonotonic': 41058806745,
> b'ActiveState': b'inactive',
> b'AssertResult': True,
> b'AssertTimestamp': 1550516822983511,
> b'AssertTimestampMonotonic': 41004686656,
> b'ConditionResult': True,
> b'ConditionTimestamp': 1550516822983509,
> b'ConditionTimestampMonotonic': 41004686655,
> b'InactiveEnterTimestamp': 1550516877103599,
> b'InactiveEnterTimestampMonotonic': 41058806745,
> b'InactiveExitTimestamp': 1550516822984291,
> b'InactiveExitTimestampMonotonic': 41004687437,
> b'Job': (0, b'/'),
> b'StateChangeTimestamp': 1550516877103599,
> b'StateChangeTimestampMonotonic': 41058806745,
> b'SubState': b'dead'},
> []]
>
>
> and on v240, on activating (please notice 4 message)
>
> ```
> [b'org.freedesktop.systemd1.Service',
> {b'ControlPID': 0,
> b'ExecMainCode': 0,
> b'ExecMainExitTimestamp': 0,
> b'ExecMainExitTimestampMonotonic': 0,
> b'ExecMainPID': 7133,
> b'ExecMainStartTimestamp': 1550515398840688,
> b'ExecMainStartTimestampMonotonic': 1922045814,
> b'ExecMainStatus': 0,
> b'GID': 4294967295,
> b'MainPID': 7133,
> b'NRestarts': 0,
> b'Result': b'success',
> b'StatusErrno': 0,
> b'StatusText': b'',
> b'UID': 4294967295},
> [b'ExecStartPre',
> b'ExecStart',
> b'ExecStartPost',
> b'ExecReload',
> b'ExecStop',
> b'ExecStopPost']]
> [b'org.freedesktop.systemd1.Unit',
> {b'ActiveEnterTimestamp': 0,
> b'ActiveEnterTimestampMonotonic': 0,
> b'ActiveExitTimestamp': 0,
> b'ActiveExitTimestampMonotonic': 0,
> b'ActiveState': b'inactive',
> b'AssertResult': True,
> b'AssertTimestamp': 1550515398840037,
> b'AssertTimestampMonotonic': 1922045163,
> b'ConditionResult': True,
> b'ConditionTimestamp': 1550515398840035,
> b'ConditionTimestampMonotonic': 1922045161,
> b'InactiveEnterTimestamp': 0,
> b'InactiveEnterTimestampMonotonic': 0,
> b'InactiveExitTimestamp': 0,
> b'InactiveExitTimestampMonotonic': 0,
> b'InvocationID': [249,
> 205,
> 238,
> 134,
> 209,
> 51,
> 64,
> 133,
> 164,
> 25,
> 160,
> 192,
> 70,
> 197,
> 1,
> 112],
> b'Job': (903, b'/org/freedesktop/systemd1/job/903'),
> b'StateChangeTimestamp': 0,
> b'StateChangeTimestampMonotonic': 0,
> b'SubState': b'dead'},
> [b'Conditions', b'Asserts']]
> [b'org.freedesktop.systemd1.Service',
> {b'ControlPID': 0,
> b'ExecMainCode': 0,
> b'ExecMainExitTimestamp': 0,
> b'ExecMainExitTimestampMonotonic': 0,
> b'ExecMainPID': 7133,
> b'ExecMainStartTimestamp': 1550515398840688,
> b'ExecMainStartTimestampMonotonic': 1922045814,
> b'ExecMainStatus': 0,
> b'GID': 4294967295,
> b'MainPID': 7133,
> b'NRestarts': 0,
> b'Result': b'success',
> b'StatusErrno': 0,
> b'StatusText': b'',
> b'UID': 4294967295},
> [b'ExecStartPre',
> b'ExecStart',
> b'ExecStartPost',
> b'ExecReload',
> b'ExecStop',
> b'ExecStopPost']]
> [b'org.freedesktop.systemd1.Unit',
> {b'ActiveEnterTimestamp': 1550515398840853,
> b'ActiveEnterTimestampMonotonic': 1922045979,
> b'ActiveExitTimestamp': 0,
> b'ActiveExitTimestampMonotonic': 0,
> b'ActiveState': b'active',
> b'AssertResult': True,
> b'AssertTimestamp': 1550515398840037,
> b'AssertTimestampMonotonic': 1922045163,
> b'ConditionResult': True,
> b'ConditionTimestamp': 1550515398840035,
> b'ConditionTimestampMonotonic': 1922045161,
> b'InactiveEnterTimestamp': 0,
> b'InactiveEnterTimestampMonotonic': 0,
> b'InactiveExitTimestamp': 1550515398840853,
> b'InactiveExitTimestampMonotonic': 1922045979,
> b'InvocationID': [249,
> 205,
> 238,
> 134,
> 209,
> 51,
> 64,
> 133,
> 164,
> 25,
> 160,
> 192,
> 70,
> 197,
> 1,
> 112],
> b'Job': (903, b'/org/freedesktop/systemd1/job/903'),
> b'StateChangeTimestamp': 1550515398840853,
> b'StateChangeTimestampMonotonic': 1922045979,
> b'SubState': b'running'},
> [b'Conditions', b'Asserts']]
>
> ```
> and on the way out
>
> ```
> [b'org.freedesktop.systemd1.Service',
> {b'ControlPID': 0,
> b'ExecMainCode': 1,
> b'ExecMainExitTimestamp': 1550515593404243,
> b'ExecMainExitTimestampMonotonic': 2116609370,
> b'ExecMainPID': 7133,
> b'ExecMainStartTimestamp': 1550515398840688,
> b'ExecMainStartTimestampMonotonic': 1922045814,
> b'ExecMainStatus': 0,
> b'GID': 4294967295,
> b'MainPID': 0,
> b'NRestarts': 0,
> b'Result': b'success',
> b'StatusErrno': 0,
> b'StatusText': b'',
> b'UID': 4294967295},
> [b'ExecStartPre',
> b'ExecStart',
> b'ExecStartPost',
> b'ExecReload',
> b'ExecStop',
> b'ExecStopPost']]
> [b'org.freedesktop.systemd1.Unit',
> {b'ActiveEnterTimestamp': 1550515398840853,
> b'ActiveEnterTimestampMonotonic': 1922045979,
> b'ActiveExitTimestamp': 1550515593404360,
> b'ActiveExitTimestampMonotonic': 2116609486,
> b'ActiveState': b'inactive',
> b'AssertResult': True,
> b'AssertTimestamp': 1550515398840037,
> b'AssertTimestampMonotonic': 1922045163,
> b'ConditionResult': True,
> b'ConditionTimestamp': 1550515398840035,
> b'ConditionTimestampMonotonic': 1922045161,
> b'InactiveEnterTimestamp': 1550515593404360,
> b'InactiveEnterTimestampMonotonic': 2116609486,
> b'InactiveExitTimestamp': 1550515398840853,
> b'InactiveExitTimestampMonotonic': 1922045979,
> b'InvocationID': [249,
> 205,
> 238,
> 134,
> 209,
> 51,
> 64,
> 133,
> 164,
> 25,
> 160,
> 192,
> 70,
> 197,
> 1,
> 112],
> b'Job': (0, b'/'),
> b'StateChangeTimestamp': 1550515593404360,
> b'StateChangeTimestampMonotonic': 2116609486,
> b'SubState': b'dead'},
> [b'Conditions', b'Asserts']]
> ```
>
> Alvaro Leiva
>
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