Hung in D state during fclose

[Dave Chinner]

On Wed, Feb 13, 2013 at 12:12:47AM +0000, Cheung, Norman wrote:
> Dave,
> 
> One other point I have forgotten to mention is that the parent
> thread will wait for 5 minutes and then lower the thread priority
> (from -2 back to 20) and set a global variable to signal the
> threads to exit.  The blocked thread responded well and exit from
> D state and fclose completed with no error.

So it's not hung - it's just very slow?

You have 256GB of memory. It's entirely possible that you've dirtied
a large amount of memory and everything is simply stuck waiting for
writeback to occur. Perhaps you should have a look at the
utilisation of your disks when this still occurs. 'iostat -x -d -m
5' will give you some insight into utilsation when a hang occurs...

> This cause me to wonder if it  is possible that  some XFS threads
> and my application thread might be in a deadlock.  

Deadlocks are permanent, so what you are seeing is not a deadlock....

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com