[MPICH] Help with a problematic simple MPI application that creates directories

[Clements, Brent]

That worked for a bit, but when I passed the same thing to mkdir I get a
-1 failure.

My code is a bit huge for a what I want to do.

Does any one have a simple example that shows how individual mpi slaves
can create their own directories with their rank in the directory name?

I have a $25.00 thinkgeek for anyone that can help.

I'm trying to learn what I'm doing wrong and my code seems to have to
many bugs to be a good learning tool

Thanks,
BC

-----Original Message-----
From: Syed Irfan [mailto:irfan at itee.uq.edu.au] 
Sent: Wednesday, September 27, 2006 4:27 PM
To: Clements, Brent
Subject: Re: [MPICH] Help with a problematic simple MPI application that
creates directories

Hi,

basedir is a char * so you need to allocate memory. There is no common 
memory allocation for basedir in child/slave process, but you are 
assigning it to "/tmp". And that should be strcpy(basedir, "/tmp")

hth
Irfan

Clements, Brent wrote:
>
> Ok, the goal of the mpi application is to take 3 arguments.... -a
NUMBER 
> of Directories to create -b the number of files to create in each 
> directory -c the /basedir to use as the directory creation point.
>
> I have written this mpi application and I'm at a point where I'm 
> trying to debug why the individual slave mpi processes aren't actually

> performing the mkdir.
>
> I've attached the source to this email if someone wouldn't mind taking

> a peek and seeing what I'm doing wrong.
>
> To compile just type
>
> Mpicc -DDEBUG test4.c -o test4
>
> To run the app just do mpirun -np 3 ./test4 -a 3 -c /tmp
>
> The arguments don't really do anything yet(but you need them to run 
> the app), since in the code I have some hard coded values.
>
> My problem is the "mkdir" part of the code...it never makes the
directory
>
> I'd appreciate anyones help with this!!
>
> I have a $25.00 gift certificate to Thinkgeek to anyone that can help 
> me out and point out my probably stupid mistake.
>
> Btw, don't snicker, YES THE CODE IS BAD, I just need something as a 
> proof of concept for my relearning of MPI and I've been fighting this 
> thing for the past 2 hours.
>
> Thanks,
>
> BC
>
> SOURCE CODE BELOW:
>
> #include <stdio.h> /* all IO stuff lives here */
>
> #include <stdlib.h> /* exit lives here */
>
> #include <unistd.h> /* getopt lives here */
>
> #include <errno.h> /* UNIX error handling lives here */
>
> #include <string.h> /* strcpy lives here */
>
> #include <mpi.h> /* MPI and MPI-IO live here */
>
> #include <sys/stat.h>
>
> #define MASTER_RANK 0
>
> #define TRUE 1
>
> #define FALSE 0
>
> #define BOOLEAN int
>
> int main( argc, argv )
>
> int argc;
>
> char * argv [];
>
> {
>
> /* my variables */
>
> int my_rank, i, numdirs, numfiles, pool_size;
>
> BOOLEAN i_am_the_master = FALSE, input_error = FALSE;
>
> char * basedir;
>
> char * dir_name = NULL;
>
> char rankdirname[300];
>
> /* getopt variables */
>
> extern char* optarg;
>
> int c;
>
> /* error handling variables */
>
> extern int errno;
>
> /* ACTION */
>
> MPI_Init(&argc, &argv);
>
> MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
>
> MPI_Comm_size(MPI_COMM_WORLD, &pool_size);
>
> if (my_rank == MASTER_RANK)
>
> i_am_the_master = TRUE;
>
> if (i_am_the_master)
>
> {
>
> /* read the command line */
>
> while ((c = getopt(argc, argv, "a:b:c:")) != -1)
>
> switch( c )
>
> {
>
> case 'a':
>
> numdirs = atoi(optarg);
>
> break;
>
> case 'b':
>
> numfiles = atoi(optarg);
>
> break;
>
> case 'c':
>
> basedir = optarg;
>
> break;
>
> case '?':
>
> return 1;
>
> default:
>
> abort();
>
> }
>
> #ifdef DEBUG
>
> printf("basedirname = %s\n", basedir);
>
> printf("number_of_directorys = %d\n", numdirs);
>
> #endif
>
> } /* end of if(i_am_the_master) { <read the command line> } */
>
> /* Transmit the effect of reading the command line to other
>
> processes. */
>
> /* If we managed to get here, data read from the command line
>
> is probably OK. */
>
> MPI_Bcast(&basedir, sizeof(basedir), MPI_CHAR, MASTER_RANK, 
> MPI_COMM_WORLD);
>
> MPI_Bcast(&numdirs, 1, MPI_INT, MASTER_RANK, MPI_COMM_WORLD);
>
> if (!i_am_the_master)
>
> {
>
> /* Now every process creates its own directory based upon its own rank
*/
>
> /* PROBLEMATIC CODE */
>
> basedir = "/tmp";
>
> // Create this processes directory name based upon it's rank
>
> sprintf(rankdirname, "RANK%d", my_rank);
>
> // Change to the base dir /tmp
>
> chdir(basedir);
>
> // make the directory
>
> mkdir(rankdirname, S_IRWXU);
>
> printf("Creating Directory: %s/%s\n", basedir, rankdirname);
>
> /* PROBLEMATIC CODE */
>
> printf("number_of_directorys = %d\n", numdirs);
>
> printf("MY RANK = %d\n", my_rank);
>
> }
>
> else
>
> {
>
> printf("MY RANK = %d\n", my_rank);
>
> }
>
> MPI_Finalize();
>
> exit(0);
>
> }
>
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