Any way to over-ride the "-q" option to debug a possible race condition?

Laurence Marks L-marks at
Thu Jul 18 23:22:52 EST 2013

I have a slightly complicated question. I am using an mpi application
(Intel impi) which uses ssh to launch applications. For about 0.1-0.2%
of the ssh connections I end up with a zombie, i.e. ps will show [ssh]
<defunct>. Something is going wrong with the ssh when it starts,
perhaps a race condition, it is not disconnecting after some time,
that I have been able to verify.

The most obvious thing I can think of to do is include LogLevel DEBUG
in my .ssh/config to try and trace what is going on, but the ssh
process is being launched with a "-q" embedded in it which is
over-riding this. I am hopeful that there is something I can set to
short-circuit the "-q", although I realise that the chance of their
being some undocumented option is small (but finite).

For reference
 ssh -V
OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010
impi 4.1

The structure is that mpirun starts mpiexec.hydra which is turn
launches a series of mpi tasks via a ssh connection.

N.B., if there are some known issues with that ssh version that may be
relevant, information would be useful as I could push on the

Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi

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