Hosting filePro applications

[Bill Campbell]

On Mon, Jan 23, 2006, Fairlight wrote:
>>From inside the gravity well of a singularity, Kenneth Brody shouted:
>> Quoting Fairlight (Mon, 23 Jan 2006 12:15:27 -0500):
>> [...]
>> > d) CPU hogging.  If you leave fP on linux at the "select file" screen
>> > (or any other of that kind), someone uses waitkey, etc., and you're
>> > timesharing a system, that's potentially a nightmare wherein those
>> > polling loops eat CPU in realtime.
>> 
>> None of the above-listed items eat CPU.
>
>That actually depends on your environment.  I just did more testing to
>track down the -specific- cause.
>
>> [...]
>> > There are (what I consider bugs, like that polling loop) issues in fP
>> > that don't lend themselves towards a friendly multi-company shared
>> 
>> What polling loops?
>
>I thought it was a polling loop because of the way it ate CPU.  It seemed
>consistent with one.  Apparently it's not, upon more rigorous testing, and
>I can verify that now.  However, there is a race condition issue.  Lesson
>to me--don't go on first (or second) impressions.
>
>This isn't something isolated to one system.  I've seen this on several
>servers, and can replicate it at will.

The strace program is a very useful tool on Linux systems.  If a process is
hanging ``strace -p pid 2>&1 tee /tmp/debugger'' may point you in the
direction of the problem.

One of the more interestings I found with this is that the ``patch''
program looks for the original files that were used to generate the patch
diff file.  This can mostly cause problems, but it does it anyway.  A new
machine was hanging during rpm builds as it was applying patches, and
strace showed that patch was attempting to find files on an automounted NFS
mounted directory and the amd automounter configuration file was pointing
to a machine that wasn't available.  It took me about 30 seconds to fix the
problem once I saw that it was hanging on NFS timeouts.

Bill
--
INTERNET:   bill at Celestial.COM  Bill Campbell; Celestial Systems, Inc.
URL: http://www.celestial.com/  PO Box 820; 6641 E. Mercer Way
FAX:            (206) 232-9186  Mercer Island, WA 98040-0820; (206) 236-1676

Suppose you were an idiot.  And suppose you were a member of Congress.  But
I repeat myself.  -- Mark Twain