Zombies

[Tom C]

When doing ps -acx, I noticed a bunch of processes that should have been long dead (including cp and mv processes), marked with status "Z". I can see from the ps man pages that Z means zombie, but I can't find any explanation of how a zombie process differs from any other dead process.

1) How does a zombie differ from a dead process?

2) How does a process end up being a zombie instead of dying?

3) How do you kill a zombie (and should you)?

4) Is a zombie a bad thing?

 

[ladavacm]

Originally posted by Tom C
When doing ps -acx, I noticed a bunch of processes that should have been long dead (including cp and mv processes), marked with status "Z". I can see from the ps man pages that Z means zombie, but I can't find any explanation of how a zombie process differs from any other dead process.

1) How does a zombie differ from a dead process?

2) How does a process end up being a zombie instead of dying?

3) How do you kill a zombie (and should you)?

4) Is a zombie a bad thing?

1) by not having been reaped by one of its ancestor processes (or init)

2) see 1

3) you don't; it has terminated or been killed already; see 1

4) it is a sign of programmer error; it uses some storage for its slot in the process list, containing its name and exit status. This is very small amount of storage, but a lot of zombies add up, and counts towards kern.maxprocperuser limit

 

[tismey]

Originally posted by Tom C

3) How do you kill a zombie (and should you)?

Most sources suggest dismemberment, Chainsaws are popular methods of accomplishing this.

You should, otherwise they'll try and suck your brains out, or worse, so a little ballet dance whilst juggling their severed head.

Sorry, facetious and stupid, but Halloween approacheth....