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Re: Difference between cron daemon and cron launhing manually
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Re: Difference between cron daemon and cron launhing manually


On Jun 24, 2005, at 11:10 AM, Michael Bartosh wrote:

I'll say that I like to limit launchd to the roles of init and mach_init.

Well, mach_init is still largely separate, actually, so you're not really using launchd in that role yet anyway. That's why the mach_init items still live in /etc/mach_init.d

It makes me nervous to have launchd do the eggs-in-one basket thing. I'd
prefer to have seen Apple move to it in a more conservative fashion.

I think we actually were quite conservative in allowing for all the backwards compatibility that we did (the continued option of using cron, xinetd, inetd, etc configuration and service options). What may be less than clear to some, however, is that by using those backwards compatible mechanisms, you're missing out on new features of the system which can be quite vital to certain usage scenarios. Using cron everywhere, for example, won't allow a lot of the cleanup jobs to run (ever) if the system tends to be asleep at 3am, leading to unconstrained growth of log files, among other things. Another feature of launchd is the ability to classify jobs as "batch jobs" and have them run at a lower I/O priority, preventing them from getting in the way of high-demand applications like Final Cut Pro, which can require that quite a bit of the system's resources (and not just CPU, but I/O) be devoted exclusively to it while doing things like importing HD video. At the same time, you don't want to prevent key services from running (like those that deal with hardware events), so a richer mechanism than cron or xinetd becomes necessary. Those are just a few of launchd's features, and there's more to its feature set that you simply cannot achieve with the historical set of daemon-management services. We didn't just do launchd as "consolidation move", it was designed to solve a number of problems we faced on the platform.

Also note that certain aspects of launchd wrt cron are still broken in 10.4.1
(I believe it is the key that has something execute on an interval, rather
than at a specified time).

Have you filed a bug report on this? I'd like to look it up, if you have the bug #. Thanks.

- Jordan


On Jun 24, 2005, at 6:36 AM, Sathish Kumar.S wrote:


Hi all,
         I am working in MacOS X. In most of the systems, I find
that, cron job is started as a daemon at the system startup. Is
this by default in all the OS ? (including TIGER) I am killing the
cron process that was running from the startup and lunching it
again from the root context. Is there any difference in these two
cron process ? I am facing a problem here. I am double forking and
launching a application. It was launched properly, if I don’t kill
this cron and relaunch it.But when I do this, this application is
not launched properly.

       Is this because of this cron launched manually ? Is there
any difference between these 2 cron process (the one which was
running from the startup and the one which is launched manually
from root context).

       Expecting positive answers,

With regards
Sathish Kumar.S

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--
Jordan K. Hubbard
Director, UNIX Technology
Apple Computer







--
Jordan K. Hubbard
Director, UNIX Technology
Apple Computer




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References: 


 >Difference between cron daemon and cron launhing manually (From: "Sathish Kumar.S " <email@hidden>)


 >Re: Difference between cron daemon and cron launhing manually (From: "Jordan K. Hubbard" <email@hidden>)


 >Re: Difference between cron daemon and cron launhing manually (From: Michael Bartosh <email@hidden>)























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