Re: LAM: Does lamhalt use LAM_MPI_SESSION_SUFFIX

I understand the first paragraph about the different lam
universes.
If LAM_MPI_SESSION_SUFFIX is set, then I can follow how
lamhalt can use
that to decide which lam daemon to kill.  However, suppose
one used the
-sessionsuffix argument to lamboot instead of the
LAM_MPI_SESSION_SUFFIX.  Since the environment variable is
not set when
lamhalt is issued, how then does lamhalt decide which is the
correct
sessionsuffix to chose to halt the particular lam universe.


-----Original Message-----
From: Brian Barrett [mailto:brbarretlam-mpi.org] 
Sent: Tuesday, July 17, 2007 9:59 PM
To: General LAM/MPI mailing list
Subject: Re: LAM: Does lamhalt use LAM_MPI_SESSION_SUFFIX


A given LAM daemon only knows the contact information for
other  
daemons in it's "universe", which is the group of
daemons started  
with the 'lamboot' command.  Other daemons started with
other calls  
to 'lamboot' are in a different universe and are not in
communication  
with the first universe.

Lamhalt just sends a message to its local LAM daemon to get
all the  
daemons in the universe, then sends all of them a die
message.  The  
universe to get the information from is determined by the
session  
directory (so usually the SESSION_SUFFIX).

So as long as the same value for LAM_MPI_SESSION_SUFFIX that
was  
there when lamboot was run is there when lamhalt is run,
only those  
daemons started by the given lamboot will be killed.  All
others will  
continue on without disruption.


Brian




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The -sessionsuffix as a command line option to LAM tools is
not  
currently universally supported.  lamhalt is one of the
applications  
that does not currently support the -sessionsuffix argument.
 The  
only way to use lamhalt is to use the environment variable 

LAM_MPI_SESSION_SUFFIX.  The advantage to
LAM_MPI_SESSION_SUFFIX is  
that all LAM/MPI commands understand and obey it.

Hope this helps,

Brian


On Jul 18, 2007, at 10:57 AM, Vechinski, Douglas A. wrote:

>
> I understand the first paragraph about the different
lam universes.
> If LAM_MPI_SESSION_SUFFIX is set, then I can follow how
lamhalt can  
> use
> that to decide which lam daemon to kill.  However,
suppose one used  
> the
> -sessionsuffix argument to lamboot instead of the
> LAM_MPI_SESSION_SUFFIX.  Since the environment variable
is not set  
> when
> lamhalt is issued, how then does lamhalt decide which
is the correct
> sessionsuffix to chose to halt the particular lam
universe.
>
>
> -----Original Message-----
> From: Brian Barrett [mailto:brbarretlam-mpi.org]
> Sent: Tuesday, July 17, 2007 9:59 PM
> To: General LAM/MPI mailing list
> Subject: Re: LAM: Does lamhalt use
LAM_MPI_SESSION_SUFFIX
>
>
> A given LAM daemon only knows the contact information
for other
> daemons in it's "universe", which is the
group of daemons started
> with the 'lamboot' command.  Other daemons started with
other calls
> to 'lamboot' are in a different universe and are not in
communication
> with the first universe.
>
> Lamhalt just sends a message to its local LAM daemon to
get all the
> daemons in the universe, then sends all of them a die
message.  The
> universe to get the information from is determined by
the session
> directory (so usually the SESSION_SUFFIX).
>
> So as long as the same value for LAM_MPI_SESSION_SUFFIX
that was
> there when lamboot was run is there when lamhalt is
run, only those
> daemons started by the given lamboot will be killed. 
All others will
> continue on without disruption.
>
>
> Brian

-- 
   Brian Barrett
   LAM/MPI Developer
   Make today a LAM/MPI day!


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