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