rsh slow shutdown

Egan Ford egan at sense.net
Fri Mar 14 14:21:38 EST 2003


rsh uses privileged ports (512-1023).  So, there is a limited number of
them.  Other processes use the privileged ports reducing the total number
available.  rsh may also use 2 ports (one for stderr and one for stdout so
I've been told, but I have not seen it), and you'll also need one/processor,
not just one/node.

I recommend using ssh with non-privileged ports, then you can startup any
size job < 65536-1024 processors.

Other solutions exist using MPD and scalable rsh implementations (e.g.
pdsh).  

Turn around and ask J.P., he knows about this.

> -----Original Message-----
> From: beowulf-admin at beowulf.org 
> [mailto:beowulf-admin at beowulf.org] On Behalf Of rick bradshaw
> Sent: Thursday, March 13, 2003 9:04 AM
> To: beowulf at beowulf.org
> Subject: rsh slow shutdown
> 
> 
> I am wondering if anyone knows the solution to the following
> problem. I know first of all that rsh is not scalable but it should be
> able to hit 255 or so processes, but recently I received the following
> message when running 208 processes
> 
> Timeout in waiting for processes to exit, 16 left.  This may 
> be due to a defective
> rsh program (Some versions of Kerberos rsh have been observed 
> to have this
> problem).
> This is not a problem with P4 or MPICH but a problem with the 
> operating
> environment.  For many applications, this problem will only slow down
> process termination.
> 
> I will also include the fact that I am running redhat 7.3 with rsh
> from the redhat rsh-0.17-5 rpm.
> 
> Thanks in advance for the help.
> 
> Rick Bradshaw
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