[X-Unix] PS and Stuck Processes

Gretchen Hayman gretchen at sedl.org
Thu Mar 4 14:54:23 PST 2004

On Mar 4, 2004, at 09:58, Alex wrote:

> This is related to a query about kill I posted last month.
> First, what does it mean when ps returns U as the state of a process? 
> It does not appear in man ps.

Ouch, the dreaded U.  I posted about this a long while ago (pre 10.2.6) 
when I had issues with the WindowServer getting stuck and freezing my 
entire system.  I can't seem to find it in the archives, but I did dig 
up an old e-mail I had sent with the info in it.

The state field of U means the thread is set to the state 
TH_STATE_UNINTERRUPTIBLE (i.e. the thread is in an uninterruptible 
wait).  Top translates this to a stuck process.

> Second, is it possible to determine if a process is stuck with ps?

Yes; look for the process with the "U".

Hope this helps.


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