Re: launchd wrong behavior for nonexistent paths and crashed services
Re: launchd wrong behavior for nonexistent paths and crashed services
- Subject: Re: launchd wrong behavior for nonexistent paths and crashed services
- From: Kevin Van Vechten <email@hidden>
- Date: Wed, 24 Sep 2008 10:49:31 -0700
On Sep 24, 2008, at 2:41 AM, Stéphane Sudre wrote:
On Sep 15, 2008, at 7:01 PM, Terry Lambert wrote:
On Sep 15, 2008, at 9:20 AM, Cristescu Alexandru <email@hidden
> wrote:
Hello all,
launchd tries to restart indefinitely some service in
the following two cases:
1) launchd plist with wrong ProgramArguments key
"
Throttling respawn: Will start in 10 seconds
posix_spawnp("<ProgramArguments>", ...): No such file
or directory
"
The problem is very annoying if some other application
waits for this service to start.
I don't see a reasonable failure mode for this case, since if
program B needs service A, it needs service A. You might argue for
a cascade failure, where if service A won't load, B should fail in
its attempt to contact A rather than launchd answering the phone
and being unable to hand off the connection to A.
On the other hand, you could argue that while what it's trying to
launch doesn't currently exist, it will in the future as a result
of a not yet completed operation (a network mount, a disk mount for
a disk currently being fsck'ed, a thumb drive containing your ssh
keys being inserted, or the binary is in fact being generated, etc.).
You could also argue that "the plist needs fixed" and/or "do not
install busted plists in the first place".
Since there's no way to distinguish a transient vs. Permanent
failure, and you presumably intentionally installed it, you
intended launchd to keep trying.
Just to point out a real case where trying to relaunch every time
without a max retries is problematic:
In Mac OS X 10.5.4 (I haven't checked if this has been fixed in
10.5.5), AFAIK, if you do the following things:
1. Turn AirPort On
2. Enable Internet Sharing via AirPort
3. Turn AirPort Off
4. Restart
Your console.log and system.log will be filled with tons of these
records:
Sep 24 11:37:59 xxxxxxxx InternetSharing[513]: Internet Sharing
shutting down
Sep 24 11:37:59 xxxxxxxx com.apple.launchd[1]
(com.apple.InternetSharing[513]): Exited with exit code: 1
Sep 24 11:37:59 xxxxxxxx com.apple.launchd[1]
(com.apple.InternetSharing): Throttling respawn: Will start in 10
seconds
Sep 24 11:38:09 xxxxxxxx InternetSharing[514]: Internet Sharing
shutting down
Sep 24 11:38:09 xxxxxxxx com.apple.launchd[1]
(com.apple.InternetSharing[514]): Exited with exit code: 1
Sep 24 11:38:09 xxxxxxxx com.apple.launchd[1]
(com.apple.InternetSharing): Throttling respawn: Will start in 10
seconds
Using the SuccessfulExit condition is useful in cases like this. If
InternetSharing sees there's nothing to do, and exits successfully,
the job wont' be restarted until another condition is met. Please
file a radar on this specific issue.
- Kevin
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