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
|
.TH MPI_Init_thread 3 "6/24/2006" "LAM/MPI 7.1.4" "LAM/MPI"
.SH NAME
MPI_Init_thread \- Initialize the MPI execution environment
.SH SYNOPSIS
.nf
#include <mpi.h>
int
MPI_Init_thread(int *pargc, char ***pargv, int requested, int *pprovided)
.fi
.SH INPUT PARAMETERS
.PD 0
.TP
.B pargc
- Pointer to the number of arguments
.PD 1
.PD 0
.TP
.B pargv
- Pointer to the argument vector
.PD 1
.PD 0
.TP
.B requested
- Desired level of thread support
.PD 1
.PD 0
.TP
.B pprovided
- Given level of thread support
.PD 1
.SH NOTES
LAM currently supports
.I MPI_THREAD_SINGLE
,
.I MPI_THREAD_SERIALIZED
,
and
.I MPI_THREAD_FUNNELED
\&.
.I MPI_THREAD_MULTIPLE
is not yet
supported. The use of
.I MPI_INIT_THREAD
is recommended instead of
.I MPI_INIT
if an MPI program is going to be multi-threaded. However,
the
.I LAM_MPI_THREAD_LEVEL
environment variable can be used to the
same effect. See MPI_Init(3) for more details.
There is currently no distinction between
.I MPI_THREAD_SINGLE
and
.I MPI_THREAD_FUNNELED
\&.
An application using
.I MPI_THREAD_FUNNELED
promises to never call MPI from a different thread than the one that
invoked
.I MPI_INIT
(or
.I MPI_INIT_THREAD
). LAM does no checking to
ensure that this is true. As such, no locks are placed around MPI
calls to ensure that only one thread is making MPI calls at a time
(since the application has promised that only one thread will be
making MPI calls).
Using
.I MPI_THREAD_SERIALIZED
will cause LAM to place locks around all
MPI calls such that only one thread will be able to enter the MPI
library at a time; beware of this fact for portability with other MPI
implementations. Even with multiple threads, deadlock is still
possible when using
.I MPI_THREAD_SERIALIZED
-- applications still need
to be aware of this and code appropriately.
Other than this restriction, this function behaves identically to
.I MPI_INIT
(see MPI_Init(3)).
Note that both
.I MPI_INIT
and
.I MPI_INIT_THREAD
are allowed to changed
the requested thread level based on lower-level device and SSI module
initializations. For example, if a user application invokes
.I MPI_Init
, some SSI modules may require threads and therefore upgrade
the thread support level to something higher than
.I MPI_THREAD_SINGLE
\&.
.SH ERRORS
If an error occurs in an MPI function, the current MPI error handler
is called to handle it. By default, this error handler aborts the
MPI job. The error handler may be changed with
.I MPI_Errhandler_set
;
the predefined error handler
.I MPI_ERRORS_RETURN
may be used to cause
error values to be returned (in C and Fortran; this error handler is
less useful in with the C++ MPI bindings. The predefined error
handler
.I MPI::ERRORS_THROW_EXCEPTIONS
should be used in C++ if the
error value needs to be recovered). Note that MPI does
.I not
guarantee that an MPI program can continue past an error.
All MPI routines (except
.I MPI_Wtime
and
.I MPI_Wtick
) return an error
value; C routines as the value of the function and Fortran routines
in the last argument. The C++ bindings for MPI do not return error
values; instead, error values are communicated by throwing exceptions
of type
.I MPI::Exception
(but not by default). Exceptions are only
thrown if the error value is not
.I MPI::SUCCESS
\&.
Note that if the
.I MPI::ERRORS_RETURN
handler is set in C++, while
MPI functions will return upon an error, there will be no way to
recover what the actual error value was.
.PD 0
.TP
.B MPI_SUCCESS
- No error; MPI routine completed successfully.
.PD 1
.PD 0
.TP
.B MPI_ERR_ARG
- Invalid argument. Some argument is invalid and is not
identified by a specific error class. This is typically a NULL
pointer or other such error.
.PD 1
.PD 0
.TP
.B MPI_ERR_OTHER
- This error class is associated with an error code
that indicates that an attempt was made to call
.I MPI_INIT
a second
time.
.I MPI_INIT
may only be called once in a program.
.PD 1
.PD 0
.TP
.B MPI_ERR_OTHER
- Other error; use
.I MPI_Error_string
to get more
information about this error code.
.PD 1
.SH SEE ALSO
MPI_Init, MPI_Finalize, lamboot, mpirun, lamhalt, lamssi
.br
.SH MORE INFORMATION
For more information, please see the official MPI Forum web site,
which contains the text of both the MPI-1 and MPI-2 standards. These
documents contain detailed information about each MPI function (most
of which is not duplicated in these man pages).
.I http://www.mpi-forum.org/
.SH ACKNOWLEDGEMENTS
The LAM Team would like the thank the MPICH Team for the handy program
to generate man pages ("doctext" from
.I ftp://ftp.mcs.anl.gov/pub/sowing/sowing.tar.gz
), the initial
formatting, and some initial text for most of the MPI-1 man pages.
.SH LOCATION
initthr.c
|
