Ubuntu Manpage: pvm_spawn - Starts new PVM processes.

NAME

       pvm_spawn - Starts new PVM processes.

SYNOPSIS

       C    int numt = pvm_spawn( char *task, char **argv, int flag,
       char *where, int ntask, int *tids )

       Fortran   call pvmfspawn( task, flag, where, ntask, tids, numt )

PARAMETERS

task Character string which is the executable file name of the PVM process to be started. The
executable must already reside on the host on which it is to be started. The name may be a file
in the PVM search path or an absolute path. The default PVM search path is
$HOME/pvm3/bin/$PVM_ARCH/ .

argv Pointer to an array of arguments to the executable (if supported on the target machine), not
including the executable name, with the end of the array specified by NULL. argv[0] of the
spawned task is set to the executable path relative to the PVM working directory (or absolute if
an absolute filename was specified). If the executable needs no arguments, then the second
argument to pvm_spawn is NULL.

flag Integer specifying spawn options.

In C, flag should be the sum of:
Option value MEANING
PvmTaskDefault 0 PVM can choose any machine to start task
PvmTaskHost 1 where specifies a particular host
PvmTaskArch 2 where specifies a type of architecture
PvmTaskDebug 4 Start up processes under debugger
PvmTaskTrace 8 Processes will generate PVM trace data. *
PvmMppFront 16 Start process on MPP front-end.
PvmHostCompl 32 Use complement host set

In Fortran, flag should be the sum of:
Option value MEANING
PVMDEFAULT 0 PVM can choose any machine to start task
PVMHOST 1 where specifies a particular host
PVMARCH 2 where specifies a type of architecture
PVMDEBUG 4 Start up processes under debugger
PVMTRACE 8 Processes will generate PVM trace data. *

* future extension

where Character string specifying where to start the PVM process. Depending on the value of flag,
where can be a host name such as "ibm1.epm.ornl.gov" or a PVM architecture class such as "SUN4".
Also, the host name "." is taken as the localhost. If flag is 0, then where is ignored when
determining the target host or architecture, and PVM will select the most appropriate host.

The where argument can also be used to specify a custom working directory for each given spawn
command. This is done by appending a ':' and the desired working directory path to the where
string, i.e.:

"ibm1.epm.ornl.gov:/home/user/project/foo"

PVM will temporarily change the working directory to spawn the given task(s), and will then reset
to the default working directory after the spawn is executed. This option need not be used in
conjunction with either the PvmTaskHost or PvmTaskArch flags, as the working directory path is
stripped off prior to parsing any host or architecture name. A valid specification for where is
therefore:

":/home/user/project/foo"

The working directory can be either an absolute path name or can be relative to the current
default working directory.

ntask Integer specifying the number of copies of the executable to start.

tids Integer array of length ntask returning the tids of the PVM processes started by this pvm_spawn
call.

numt Integer returning the actual number of tasks started. Values less than zero indicate a system
error. A positive value less than ntask indicates a partial failure. In this case the user
should check the tids array for the error code(s).

DESCRIPTION

The routine pvm_spawn starts ntask copies of the executable named task. On systems that support
environment, spawn passes selected variables from parent environment to children tasks. If set, the
envar PVM_EXPORT is passed. If PVM_EXPORT contains other names (separated by ':') they will be passed
too. This is useful for e.g.:

setenv DISPLAY myworkstation:0.0
setenv MYSTERYVAR 13
setenv PVM_EXPORT DISPLAY:MYSTERYVAR

The hosts on which the PVM processes are started are determined by the flag and where arguments. On
return the array tids contains the PVM task identifiers for each process started.

If pvm_spawn starts one or more tasks, numt will be the actual number of tasks started. If a system
error occurs then numt will be < 0. If numt is less than ntask then some executables have failed to
start and the user should check the last ntask - numt locations in the tids array which will contain
error codes (see below for meaning). The first numt tids in the array are always valid.

When flag is set to 0 and where is set to NULL (or "*" in Fortran) a heuristic (round-robin assignment)
is used to distribute the ntask processes across the virtual machine.

If the PvmHostCompl flag is set, the resulting host set gets complemented. Given that the TaskHost host
name "." is taken as localhost, these can be used together, for example, to request n - 1 tasks on host
"." but with flags TaskHost|HostCompl to spawn n - 1 tasks on hosts other than the localhost.

In the special case where a multiprocessor is specified by where, pvm_spawn will start all ntask copies
on this single machine using the vendor's underlying routines.

The spawned task will have argv[0] set to the the executable path relative to its inherited working
directory (or possibly an absolute path), so the base filename can be got by using:
char *p;
p = (p = rindex(argv[0], '/')) ? p + 1 : argv[0];

If PvmTaskDebug is set, then the pvmd will start the task(s) under debugger(s). In this case, instead of
executing pvm3/bin/ARCH/task args it executes pvm3/lib/debugger pvm3/bin/ARCH/task args. debugger is a
shell script that the users can modify to their individual tastes. Presently the script starts an xterm
with dbx or comparable debugger in it.

EXAMPLES

       C:
            numt = pvm_spawn( "host", 0, PvmTaskHost, "sparky", 1, &tid[0] );
            numt = pvm_spawn( "host", 0, (PvmTaskHost+PvmTaskDebug),
                           "sparky", 1, &tid[0] );
            numt = pvm_spawn( "node", 0, PvmTaskArch, "RIOS", 1, &tid[i] );

            char *args[] = { "12", "60" , (char*)0 };
            numt = pvm_spawn( "FEM1", args, 0, 0, 16, tids );

            numt = pvm_spawn( "pde", 0, PvmTaskHost, "paragon.ornl", 512, tids );

       Fortran:
            FLAG = PVMARCH + PVMDEBUG
            CALL PVMFSPAWN( 'node', FLAG, 'SUN4', 1, TID(3), NUMT )
            CALL PVMFSPAWN( 'FEM1', PVMDEFAULT, '*', 16, TIDS, NUMT )
            CALL PVMFSPAWN( 'TBMD', PVMHOST, 'cm5.utk.edu', 32, TIDS, NUMT )

ERRORS