1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
|
.. _mpi_comm_spawn_multiple:
MPI_Comm_spawn_multiple
=======================
.. include_body
:ref:`MPI_Comm_spawn_multiple` |mdash| Spawns multiple binaries, or the same
binary with multiple sets of arguments.
SYNTAX
------
C Syntax
^^^^^^^^
.. code-block:: c
#include <mpi.h>
int MPI_Comm_spawn_multiple(int count, char *array_of_commands[],
char **array_of_argv[], const int array_of_maxprocs[], const MPI_Info
array_of_info[], int root, MPI_Comm comm, MPI_Comm *intercomm,
int array_of_errcodes[])
Fortran Syntax
^^^^^^^^^^^^^^
.. code-block:: fortran
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_SPAWN_MULTIPLE(COUNT, ARRAY_OF_COMMANDS, ARRAY_OF_ARGV,
ARRAY_OF_MAXPROCS, ARRAY_OF_INFO, ROOT, COMM, INTERCOMM,
ARRAY_OF_ERRCODES, IERROR)
INTEGER COUNT, ARRAY_OF_INFO(*), ARRAY_OF_MAXPROCS(*), ROOT,
COMM, INTERCOMM, ARRAY_OF_ERRCODES(*), IERROR
CHARACTER*(*) ARRAY_OF_COMMANDS(*), ARRAY_OF_ARGV(COUNT, *)
Fortran 2008 Syntax
^^^^^^^^^^^^^^^^^^^
.. code-block:: fortran
USE mpi_f08
MPI_Comm_spawn_multiple(count, array_of_commands, array_of_argv,
array_of_maxprocs, array_of_info, root, comm, intercomm,
array_of_errcodes, ierror)
INTEGER, INTENT(IN) :: count, array_of_maxprocs(*), root
CHARACTER(LEN=*), INTENT(IN) :: array_of_commands(*)
CHARACTER(LEN=*), INTENT(IN) :: array_of_argv(count, *)
TYPE(MPI_Info), INTENT(IN) :: array_of_info(*)
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Comm), INTENT(OUT) :: intercomm
INTEGER :: array_of_errcodes(*)
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
INPUT PARAMETERS
----------------
* ``count``: Number of commands (positive integer, significant to MPI only at *root* |mdash| see NOTES).
* ``array_of_commands``: Programs to be executed (array of strings, significant only at *root*).
* ``array_of_argv``: Arguments for *commands* (array of array of strings, significant only at *root*).
* ``array_of_maxprocs``: Maximum number of processes to start for each command (array of integers, significant only at *root*).
* ``array_of_info``: Info objects telling the runtime system where and how to start processes (array of handles, significant only at *root*).
* ``root``: Rank of process in which previous arguments are examined (integer).
* ``comm``: Intracommunicator containing group of spawning processes (handle).
OUTPUT PARAMETERS
-----------------
* ``intercomm``: Intercommunicator between original group and the newly spawned group (handle).
* ``array_of_errcodes``: One code per process (array of integers).
* ``ierror``: Fortran only: Error status (integer).
DESCRIPTION
-----------
:ref:`MPI_Comm_spawn_multiple` is identical to :ref:`MPI_Comm_spawn` except that it
can specify multiple executables. The first argument, *count*, indicates
the number of executables. The next three arguments are arrays of the
corresponding arguments in :ref:`MPI_Comm_spawn`. The next argument,
*array_of_info*, is an array of *info* arguments, one for each
executable. See the INFO ARGUMENTS section for more information.
For the Fortran version of *array_of_argv*, the element
*array_of_argv*\ (i,j) is the jth argument to command number i.
In any language, an application may use the constant MPI_ARGVS_NULL
(which is likely to be ``(char **)0`` in C) to specify that no arguments
should be passed to any commands. The effect of setting individual
elements of *array_of_argv* to MPI_ARGV_NULL is not defined. To specify
arguments for some commands but not others, the commands without
arguments should have a corresponding *argv* whose first element is null
``((char *)0`` in C and empty string in Fortran).
All of the spawned processes have the same MPI_COMM_WORLD. Their ranks
in MPI_COMM_WORLD correspond directly to the order in which the commands
are specified in :ref:`MPI_Comm_spawn_multiple`. Assume that m1 processes are
generated by the first command, m2 by the second, etc. The processes
corresponding to the first command have ranks 0, 1,..., m1-1. The
processes in the second command have ranks m1, m1+1, ..., m1+m2-1. The
processes in the third have ranks m1+m2, m1+m2+1, ..., m1+m2+m3-1, etc.
The *array_of_errcodes* argument is 1-dimensional array of size
::
_ count
\ n ,
/_ i=1 i
where i is the ith element of *array_of_maxprocs*. Command number *i*
corresponds to the i contiguous slots in this array from element
::
_ _
_ i-1 | _ i |
\ n , to | \ n | -1
/_ j=1 i | /_ j=1 j |
|_ _|
Error codes are treated as for :ref:`MPI_Comm_spawn`.
INFO ARGUMENTS
--------------
The following keys for *info* are recognized in "#PACKAGE_NAME#". (The
reserved values mentioned in Section 5.3.4 of the MPI-2 standard are not
implemented.)
::
Key Type Description
--- ---- -----------
host char * Comma-separated list of hosts on which
the processes should be spawned. See
the orte_host man page for an
explanation of how this will be used.
hostfile char * Hostfile containing the hosts on which
the processes are to be spawned. See
the orte_hostfile man page for
an explanation of how this will be
used.
add-host char * Add the specified hosts to the list of
hosts known to this job and use it for
the associated processes. This will be
used similarly to the -host option.
add-hostfile char * Hostfile containing hosts to be added
to the list of hosts known to this job
and use it for the associated
process. This will be used similarly
to the -hostfile option.
wdir char * Directory where the executable is
located. If files are to be
pre-positioned, then this location is
the desired working directory at time
of execution - if not specified, then
it will automatically be set to
ompi_preload_files_dest_dir.
ompi_prefix char * Same as the --prefix command line
argument to mpirun.
ompi_preload_binary bool If set to true, pre-position the
specified executable onto the remote
host. A destination directory must
also be provided.
ompi_preload_files char * A comma-separated list of files that
are to be pre-positioned in addition
to the executable. Note that this
option does not depend upon
ompi_preload_binary - files can
be moved to the target even if an
executable is not moved.
ompi_stdin_target char * Comma-delimited list of ranks to
receive stdin when forwarded.
ompi_non_mpi bool If set to true, launching a non-MPI
application; the returned communicator
will be MPI_COMM_NULL. Failure to set
this flag when launching a non-MPI
application will cause both the child
and parent jobs to "hang".
ompi_param char * Pass an OMPI MCA parameter to the
child job. If that parameter already
exists in the environment, the value
will be overwritten by the provided
value.
mapper char * Mapper to be used for this job
map_by char * Mapping directive indicating how
processes are to be mapped (slot,
node, socket, etc.).
rank_by char * Ranking directive indicating how
processes are to be ranked (slot,
node, socket, etc.).
bind_to char * Binding directive indicating how
processes are to be bound (core, slot,
node, socket, etc.).
path char * List of directories to search for
the executable
npernode char * Number of processes to spawn on
each node of the allocation
pernode bool Equivalent to npernode of 1
ppr char * Spawn specified number of processes
on each of the identified object type
env char * Newline-delimited list of envars to
be passed to the spawned procs
*bool* info keys are actually strings but are evaluated as follows: if
the string value is a number, it is converted to an integer and cast to
a boolean (meaning that zero integers are false and non-zero values are
true). If the string value is (case-insensitive) "yes" or "true", the
boolean is true. If the string value is (case-insensitive) "no" or
"false", the boolean is false. All other string values are unrecognized,
and therefore false.
Note that if any of the info handles have *ompi_non_mpi* set to true,
then all info handles must have it set to true. If some are set to true,
but others are set to false (or are unset), MPI_ERR_INFO will be
returned.
Note that in "#PACKAGE_NAME#", the first array location in
*array_of_info* is applied to all the commands in *array_of_commands*.
NOTES
-----
The argument *count* is interpreted by MPI only at the root, as is
*array_of_argv*. Since the leading dimension of *array_of_argv* is
*count*, a nonpositive value of *count* at a nonroot node could
theoretically cause a runtime bounds check error, even though
*array_of_argv* should be ignored by the subroutine. If this happens,
you should explicitly supply a reasonable value of *count* on the
nonroot nodes.
Similar to :ref:`MPI_Comm_spawn`, it is the application's responsibility to
terminate each individual set of argv in the *array_of_argv* argument.
In C, each argv array is terminated by a NULL pointer. In Fortran, each
argv array is terminated by an empty string (note that compilers will
not automatically insert this blank string; the application must ensure
to have enough space for an empty string entry as the last element of
the array).
Other restrictions apply to the *array_of_argv* parameter; see
:ref:`MPI_Comm_spawn`'s description of the *argv* parameter for more
details.
MPI-3.1 implies (but does not directly state) that the argument
*array_of_commands* must be an array of strings of length *count*.
Unlike the *array_of_argv* parameter, *array_of_commands* does not need
to be terminated with a NULL pointer in C or a blank string in Fortran.
Older versions of Open MPI required that *array_of_commands* be
terminated with a blank string in Fortran; that is no longer required in
this version of Open MPI.
Calling :ref:`MPI_Comm_spawn` many times would create many sets of children
with different MPI_COMM_WORLDs, whereas :ref:`MPI_Comm_spawn_multiple` creates
children with a single MPI_COMM_WORLD, so the two methods are not
completely equivalent. Also if you need to spawn multiple executables,
you may get better performance by using :ref:`MPI_Comm_spawn_multiple` instead
of calling :ref:`MPI_Comm_spawn` several times.
ERRORS
------
.. include:: ./ERRORS.rst
.. seealso::
* :ref:`MPI_Comm_spawn`
* :ref:`MPI_Comm_get_parent`
* :ref:`mpirun(1) <man1-mpirun>`
|
