Resources for learning about and dealing with "zombie" processes on Linux.

Update: I found a decent resource on zombie processes and should rewrite this page based on it:

• What is a Zombie Process and Should I be Worried That I Have Some? -- "The first thing is that you don't need to worry about zombie processes unless you have a great many of them (more than, say, 100)." (This is on Tek-Tips which I should consider joining while it's free (oh, no -- not another password!!)

See AboutThesePages.

Contents

Notes

Definitions

Here are some definitions I scribbled down from somewhere -- I don't necessarily know exactly what they mean:

Zombie: a defunct process -- a "process that has exited and has a parent that has not yet waited for the process"(?) (Hmm, maybe that means the parent hasn't yet noticed that the (child) process has exited? I assume a zombie process is a bad thing, but it doesn't quite sound that way the way it's written -- it sounds like it could be a child process that has finished its task properly and is waiting for its parent to grab its results? Or maybe the fact that it has exited means the parent cannot grab the results? Or maybe a process exiting implies a failed process??)

Blocking / hanging: "a process that is blocked trying to exit"

Finding A Zombie

In both top and ps, there is a column for status (on ps it is the second column -- I've overlooked it a few times) -- a Z in that column (possibly along with some other status notations (?) means it is a zombie).

Implications of a Zombie

Not sure. I have instances of poor performance on System5 -- last time I checked there were 3 zombie processes. I had planned to find them and get rid of them to see if performance improved -- by the time I figured out how to find them, they were gone. I'm not sure I recognized any performance improvement -- the other thing I noticed (at that time and fairly often when performance deteriorates) are some kdeinit or kmail processes that are each trying to use all the available CPU (they might each say they are using 90%+, but of course the total usage cannot exceed 100%). I usually quit kmail, kill those processes, restart kmail, and performance is back to "normal" again.

Resources

See ResourceRecommendations. Feel free to add additional resources to these lists, but please follow the guidelines on ResourceRecommendations including ResourceRecommendations#Guidelines_for_Rating_Resources.

Recommended

• Google search on [zombie Linux process find]
• (rhk) [[][]] --

Recommended for Specific Needs

• (rhk) [[][]] --

Recommended by Others

• (rhk) [[][]] --

No Recommendation

• Subject: Monitoring hanging/zombie processes -- seems confusing -- might get better by the end
• (rhk) [[][]] --

Not Recommended

• (rhk) [[][]] --

Contributors

• () RandyKramer - 26 Sep 2002
• <If you edit this page: add your name here; move this to the next line; and include your comment marker (initials), if you have created one, in parenthesis before your WikiName.>

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