[mpich-discuss] command line ordering of hosts matters?

David_Lowinger at ea.epson.com David_Lowinger at ea.epson.com
Mon Jul 26 15:20:49 CDT 2010


We removed the "primary DNS suffix" from 10.0.0.6, and everything seems to 
work now.  The "helloworld" app no longer crashes, and the ordering of 
hosts no longer matters.
Thank you for your guidance,
David




jayesh at mcs.anl.gov 
07/23/2010 03:42 PM
Expire Date: 07/25/2012


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Re: [mpich-discuss] command line ordering of hosts matters?






Hi,
 From the error message, gethostbyname() fails for ipaddress 10.0.0.6. 
Looks like the DNS entries for the host is incomplete. Can you (or a 
sysadmin) verify that the DNS entries for the host is actually 
valid/complete ?
 Can you also try the newer nemesis channel (which will be the default 
channel, replacing the sock channel, in 1.3 series) and see if it works 
(mpiexec -channel nemesis -hosts 2 10.0.0.6 1 10.0.0.1 1 helloworld.exe)?

Regards,
Jayesh
----- Original Message -----
From: "David Lowinger" <David_Lowinger at ea.epson.com>
To: mpich-discuss at mcs.anl.gov
Sent: Friday, July 23, 2010 2:24:02 PM GMT -06:00 US/Canada Central
Subject: Re: [mpich-discuss] command line ordering of hosts matters?




Hi Jayesh, 
I do indeed see 1 instance of my MPI program ("myapp.exe") on each 
machine's Process Manager whenever I run any test, whether the MPI_Bcast 
fails or not. So, it looks like both machines are successfully launching 
processes. 

Yes, I am running the 64-bit version of MPICH2 on both the machines. I 
just tried recompiling the code separately on both the machines, and I see 
the exact same result as before ( ie. the MPI_Bcast never completes if I 
put 10.0.0.101 before 10.0.0.6 ). 

I tried both the simple hello world program and the compute pi example 
that you sent in the links. The simple "hello world" program actually 
crashes... this is very odd, because I've successfully run much more 
complex apps than this with no problems. Please see the attached file 
("helloworld_output.jpg") for the error I get when I run the 
https://svn.mcs.anl.gov/repos/mpi/mpich2/trunk/examples/hellow.c example. 
I see this crash as long as I use 2 hosts, listed in either order on the 
command line. If I only use 1 host (ie. "mpiexec -np 5 helloworld.exe"), 
it runs fine. 

The PI example seems to have the same "host ordering" issue I initially 
described to you. If I place 10.0.0.6 first in the command line, there's 
no problem (apart from me being unable to input the value for 'n' using 
scanf... instead, I just commented out the scanf section and hardcoded 'n' 
to be 5). If 10.0.0.6 is not listed first, the PI calculation app never 
gets past the initial call to 'MPI_Bcast()'. 

David 



                 Jayesh Krishna <jayesh at mcs.anl.gov> 

07/13/2010 08:56 PM 
Expire Date: 07/22/2012 
 
To               mpich-discuss at mcs.anl.gov 
 
cc               David_Lowinger at ea.epson.com 
 
Subject                  Re: [mpich-discuss] command line ordering of 
hosts matters? 
 



Hi, 
Sorry for the delayed response. 
Since you are able to run "hostname" on the two machines the process 
manager should be able to launch processes on the two machines (In the 
process manager tab you should see 1 instance of your MPI program, 
MYMPIPGM.exe, on each machine). 
Are you running a 64-bit version of MPICH2 on both the machines ? Have you 
recompiled your code on both the machines ? Did you try a simple hello 
world program to see if it works (
https://svn.mcs.anl.gov/repos/mpi/mpich2/trunk/examples/hellow.c)? Try 
compiling the compute pi example to see if it works (
https://svn.mcs.anl.gov/repos/mpi/mpich2/trunk/examples/icpi.c - Make sure 
that you compile the code separately on both the machines)? 
Let us know the results. 

Regards, 
Jayesh 

----- Original Message ----- 
From: "David Lowinger" <David_Lowinger at ea.epson.com> 
To: mpich-discuss at mcs.anl.gov 
Sent: Monday, July 5, 2010 11:11:16 AM GMT -06:00 US/Canada Central 
Subject: Re: [mpich-discuss] command line ordering of hosts matters? 



Hi Jayesh, 

Yes, I can run a simple non-MPI program (ie. the program "hostname") 
successfully with " mpiexec -hosts 2 10.0.0.101 1 10.0.0.6 1 hostname ". I 
see both hostnames get printed out, and then the program exits. The 
ordering of hosts does not matter in this case. 
I see the exact same behavior as before when I provide the complete path 
to the executable; ie. the MPI_Bcase never completes if I put 10.0.0.101 
before 10.0.0.6. 
I see the exact same behavior as before when I use the machinefile option. 


With regards to checking the control panel, I assume you mean the 
"Processes" tab of the Windows Task Manager? If so, which processes should 
I be looking for as the program runs? I changed the MPI "hello world" app 
to MPI_Bcast a very large buffer over and over, so that I can look for 
some kind of process in the Windows Task Manager. What is the name of the 
process I should be looking for? Thanks, 

David 



Jayesh Krishna <jayesh at mcs.anl.gov> 

07/01/2010 11:54 AM 
Expire Date: 07/04/2012 

To mpich-discuss at mcs.anl.gov 

cc David_Lowinger at ea.epson.com 

Subject Re: [mpich-discuss] command line ordering of hosts matters? 




Hi, 
Along with checking whether the processes are launched, please provide us 
with the information below, 

# Are you able to run a simple non-MPI program (mpiexec -hosts 2 
10.0.0.101 1 10.0.0.6 1 hostname)? 
# Try providing the complete path to the executable (mpiexec -hosts 2 
10.0.0.101 1 10.0.0.6 1 c:\temp\helloworld.exe). Without the complete path 
you might actually be executing two different MPI programs on the hosts. 
# Does the machinefile option work (mpiexec -n 2 -machinefile mf.txt 
c:\temp\helloworld.exe ; Where the file mf.txt contains the host 
ipaddresses)? 

Regards, 
Jayesh 
----- Original Message ----- 
From: "David Lowinger" <David_Lowinger at ea.epson.com> 
To: mpich-discuss at mcs.anl.gov 
Sent: Wednesday, June 30, 2010 4:26:16 PM GMT -06:00 US/Canada Central 
Subject: Re: [mpich-discuss] command line ordering of hosts matters? 



Hi Jayesh, 
On both machines, when I type, "smpd -version", both display "1.2.1p1". 
When I call "MPI_Get_version()" on both machines, they both show version 
2, subversion 2. 

Both machines are running 64-bit Windows Vista. 

I'll check the control panel to see if the MPI processes are being 
launched. 

David 



Jayesh Krishna <jayesh at mcs.anl.gov> 

06/30/2010 04:53 PM 
Expire Date: 06/29/2012 

To mpich-discuss at mcs.anl.gov 

cc David_Lowinger at ea.epson.com 

Subject Re: [mpich-discuss] command line ordering of hosts matters? 




Hi, 
Which version of MPICH2 are you using ? 
Do the two machines have the same underlying architecture (MPICH2 
currently does not support heterogeneous systems - So you cannot run your 
job across 32-bit and 64-bit machines/MPICH2_libs)? 
Also try checking the control panel to see if the MPI processes are being 
launched on the machines. 

Regards, 
Jayesh 

----- Original Message ----- 
From: "David Lowinger" <David_Lowinger at ea.epson.com> 
To: mpich-discuss at mcs.anl.gov 
Sent: Wednesday, June 30, 2010 3:42:22 PM GMT -06:00 US/Canada Central 
Subject: Re: [mpich-discuss] command line ordering of hosts matters? 



Firewall is turned off on both machines. 
There is no error message... the MPI_Bcase simply never completes. I've 
left it running for 10 minutes, and the second printf ("completed 
MPI_Bcast") never appears when I use the second host ordering below 
("10.0.0.101 1 10.0.0.6 1"). 
When I run "smpd -status 10.0.0.6" from 10.0.0.101, I see the message 
"smpd running on 10.0.0.6". When I run "smpd -status 10.0.0.101" from 
10.0.0.6, I see the message "smpd running on 10.0.0.101". 



jayesh at mcs.anl.gov 

06/30/2010 10:50 AM 
Expire Date: 06/29/2012 

To mpich-discuss at mcs.anl.gov 

cc David_Lowinger at ea.epson.com 

Subject Re: [mpich-discuss] command line ordering of hosts matters? 




Hi, 
Do you have a firewall running on any of these machines (If so, can you 
try running your job after turning off the firewall)? 
What is the error message that you get when you run your job ? 
Can you try running "smpd -status REMOTE_MACHINE" from each of the 
machines and let us know the results ("smpd -status 10.0.0.6" from 
10.0.0.101 & "smpd -status 10.0.0.101" from 10.0.0.6)? 

Regards, 
Jayesh 
----- Original Message ----- 
From: "David Lowinger" <David_Lowinger at ea.epson.com> 
To: mpich-discuss at mcs.anl.gov 
Sent: Tuesday, June 29, 2010 5:53:07 PM GMT -06:00 US/Canada Central 
Subject: [mpich-discuss] command line ordering of hosts matters? 



Hi, 
When running a very basic "hello world" app, I've found that the app's 
behavior depends on the order I use for hosts in the command line. For 
example, if I use: 

mpiexec -hosts 2 10.0.0.6 1 10.0.0.101 1 helloworld.exe 

The program executes flawlessly. But, if I use: 

mpiexec -hosts 2 10.0.0.101 1 10.0.0.6 1 helloworld.exe 

then the program never gets past the call to "MPI_Bcast()". Here is my 
code: 

------------------- 

#include "mpi.h" 

#define MPI_FLUSH() fflush(stdout) 

int main( int argc, char* argv[] ) 
{ 
int g_Thread_ID, g_Num_Threads; 
int test = 0; 

/**************************************************\ 
* MPI Initialization * 
\**************************************************/ 
MPI_Init(&argc, &argv); 
MPI_Comm_rank(MPI_COMM_WORLD, &g_Thread_ID); 
MPI_Comm_size(MPI_COMM_WORLD, &g_Num_Threads); 

printf("thread %d: main: About to execute MPI_Bcast\n", g_Thread_ID); 
MPI_FLUSH(); 

// Broadcast integer 
int err = MPI_Bcast(&test, 1, MPI_INT, 0, MPI_COMM_WORLD); 

printf("thread %d: completed MPI_Bcast\n", g_Thread_ID); 
MPI_FLUSH(); 

MPI_Finalize(); 
} 

------------------ 

I am running Windows Vista on both machines. Has anyone seen this before? 
Thanks, 
David 

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