[launchd-dev] The "daemons must live for at least 60 seconds" factoid

[Jonathan del Strother]

Thanks for the reply - turns out that it's being relaunched because
launchd thinks one of the watch paths changed.  I'm not sure why - to
the best of my knowledge it's been read from, but not written to - but
at least it clears up one mystery.  It's actually monitoring a sqlite
database - maybe sqlite is invisibly writing to it behind the scenes,
I'll see if I can find anything with instruments...


On Wed, Aug 19, 2009 at 6:16 PM, Kevin Van Vechten<kvv at apple.com> wrote:
> In general, launchd does not relaunch processes which exit successfully.
>
> It would help if you shared the relevant portions of your launchd plist.
>
> Kevin
>
> On Aug 19, 2009, at 5:16 AM, Jonathan del Strother wrote:
>
>> It's a commonly repeated piece of folklore that if your launchdaemon
>> completes in under 60 seconds, launchd will assume it has crashed and
>> will re-launch it.  I have a LaunchAgent with a 2 minute
>> StartInterval, which exits quickly if there are no available jobs for
>> it to work on.  launchd tends to run it once due to the StartInterval,
>> then again 15 seconds later - presumably because it didn't live for at
>> least 60 seconds.  Adding "sleep(60)" to the end of my LaunchAgent
>> seems to prevent it from launching the 2nd time around.
>>
>> However, I can't find any actual documentation that mentions this,
>> and I'm sure I've heard somewhere that it was a Tiger bug/feature
>> only, due to be fixed in Leopard - this appears to not be the case.
>> It seems an odd feature, too - why relaunch something that exited with
>> a successful status code?
>>
>> Is there any official documentation of this behaviour?
>>
>> -Jonathan del Strother
>
>