Unix Shell - Zombie removables - how to ID + kill parent process?

Author

Zombie removables - how to ID + kill parent process?

Brennan Young

2007-01-19, 7:22 am

I've had this problem for a long time, and it has taken me a long time
to gather any information about it.

I have a Macintosh "MDD" machine with a second optical drive, running
Mac OS X.

This problem applies to all removables except the primary optical drive,
including iPods and USB 'key' drives.

Removables mount just fine, but if they are not accessed (read or write)
for over a minute or so, they seem to lock up. This is very annoying
because it means I have to be vigilant every time I work with removable
volumes.

Any further attempts to access the volume (including unmounting or
ejecting) causes the accessing process to freeze up, and it must be
forced to quit.

When I run 'top' subsequently I see that there is one 'stuck' thread for
every initiated access to the locked volume - i.e. a zombie process.

For example, if I attempt to access the volume from iTunes, it freezes,
and then when I force iTunes to quit, I have 1 stuck process. If I then
try to eject the volume from Finder, causing it to lock up, and then
force Finder to quit I have two stuck processes, and so on.

Typically it is 'umount' which becomes a zombie.

I'm hoping someone here can help.

Also, if anyone can suggest why this might be happening (hardware
problem?) I would be extremely grateful.

-Brennan

Jolly Roger

2007-01-19, 1:18 pm

On 2007-01-19 04:55:20 -0600, Brennan Young <brennannospam@young.net> said:

> I've had this problem for a long time, and it has taken me a long time
> to gather any information about it.
>
> I have a Macintosh "MDD" machine with a second optical drive, running Mac OS X.
>
> This problem applies to all removables except the primary optical
> drive, including iPods and USB 'key' drives.
>
> Removables mount just fine, but if they are not accessed (read or
> write) for over a minute or so, they seem to lock up. This is very
> annoying because it means I have to be vigilant every time I work with
> removable volumes.
>
> Any further attempts to access the volume (including unmounting or
> ejecting) causes the accessing process to freeze up, and it must be
> forced to quit.

(snip)

More details would be helpful:

Run /Applications/Utilities/System Profiler and give us all information
there about the second optical drive's hardware? If you are running Mac
OS X 10.4.x, it will be under the heading "Disc Burning" and also
likely some info under "ATA".

Run /Applications/Utilities/Console, then select File > Open Console
Log & File > Open System Log to view the console and system logs. What
errors are reported there when the "lock-up" happens?

--
JR

Bob Harris

2007-01-20, 1:27 am

In article
<brennannospam-A110F4.11551919012007@thomson.uni2.net>,
Brennan Young <brennannospam@young.net> wrote:

> I've had this problem for a long time, and it has taken me a long time
> to gather any information about it.
>
> I have a Macintosh "MDD" machine with a second optical drive, running
> Mac OS X.
>
> This problem applies to all removables except the primary optical drive,
> including iPods and USB 'key' drives.
>
> Removables mount just fine, but if they are not accessed (read or write)
> for over a minute or so, they seem to lock up. This is very annoying
> because it means I have to be vigilant every time I work with removable
> volumes.
>
> Any further attempts to access the volume (including unmounting or
> ejecting) causes the accessing process to freeze up, and it must be
> forced to quit.
>
> When I run 'top' subsequently I see that there is one 'stuck' thread for
> every initiated access to the locked volume - i.e. a zombie process.
>
> For example, if I attempt to access the volume from iTunes, it freezes,
> and then when I force iTunes to quit, I have 1 stuck process. If I then
> try to eject the volume from Finder, causing it to lock up, and then
> force Finder to quit I have two stuck processes, and so on.
>
> Typically it is 'umount' which becomes a zombie.
>
> I'm hoping someone here can help.
>
> Also, if anyone can suggest why this might be happening (hardware
> problem?) I would be extremely grateful.
>
> -Brennan

A Zombie process is the child of another process (the parent).
The Zombie has finished executing is waiting for the parent to ask
for the child's completion status. Until either the parent
process retrieves the childs completion status, or the parent
process exits, the zombie will sit and wait.

Generally all of the zombie process' resources have been released
except for a small bit of memory holding its completion status.

The following Terminal command:

ps ax -o pid,ppid,ucomm

will list all the processes on your system, with the process id
(pid) of the process, followed by the process' parent process id
(ppid). You can use this information to find the parent of the
zombie processes. That is the offending process that is not
properly reaping the completion status of its children.

Bob Harris

RobertB

2007-01-25, 1:19 pm