deadlock caused by idprio?

[Doug Lee]

Any hidden hazards in rtprio then?  I plan to use rtprio when
recording sound, so i/o bursts etc. won't cause things to be missed in
the recording.

Thanks much for the idprio heads-up.

And I do hope, sometime, to jump from 4 to 6 directly--though I also
plan to buy a new machine for that.  I currently run 4.10 on a P166.
Nice to have support for old hardware, and amazing that all I miss in
using it are speed of MySQL and mail searches and sound-handling
performance; but it is time...

On Sat, Nov 19, 2005 at 04:09:03PM -0500, Kris Kennaway wrote:
On Sat, Nov 19, 2005 at 01:32:36PM -0500, Doug Lee wrote:
> I just ran a MySQL lookup process (written in Perl) as root prefixed
> with "idprio 1."  I expected it to take a while, but not several
> minutes.  After a while I decided to abort it, so I typed ^c in its
> `screen' window.  From then on (either from the ^c point or the idprio
> run, I know not which), I could not create any new processes, nor
> could I kill the running task.  Any attempt to do either would hang
> indefinitely.  I could end processes and work within existing
> processes as long as they didn't try to create new ones.  I entered
> the debugger (I use the alt method of <cr>~^b) and typed, among other
> things, "show lockedvnodes" and got one vnode which said "... with 22
> pending," and this count went up by 1 each time I tried creating a new
> process.  Sadly, I forgot to snapshot that screen, so I can't quote
> the rest of that entry.  I remember it said VDIR and type
> something+VOBJECT, but I don't remember what the something was.
> Unable to retrieve my system, I finally typed "panic" in the debugger
> so at least the disks would sync.  Other than "giving up on 4
> buffers," that went fine.
> 
> Any ideas what this is, and whether it's a bug?  I thought idprio was
> harmless as far as affecting other processes.

No, it's known to cause deadlocks.  I don't know if this is still the
case on 6.0.

Kris



-- 
Doug Lee                 dgl at dlee.org        
SSB + BART Group         doug at bartsite.com   http://www.bartsite.com
"It is not the mountain in the distance which makes you want to stop
walking; but the grain of sand in your shoe."  --Anon