1 | .\"Copyright 2006-2008 Sun Microsystems, Inc. |
---|
2 | .\" Copyright (c) 1996 Thinking Machines Corporation |
---|
3 | .TH MPI_Init_thread 3 "Dec 08, 2009" "1.4" "Open MPI" |
---|
4 | |
---|
5 | .SH NAME |
---|
6 | \fBMPI_Init_thread\fP \- Initializes the MPI execution environment |
---|
7 | |
---|
8 | .SH SYNTAX |
---|
9 | .ft R |
---|
10 | |
---|
11 | .SH C Syntax |
---|
12 | .nf |
---|
13 | #include <mpi.h> |
---|
14 | int MPI_Init_thread(int *\fIargc\fP, char ***\fIargv\fP, |
---|
15 | int \fIrequired\fP, int *\fIprovided\fP) |
---|
16 | |
---|
17 | .SH Fortran Syntax |
---|
18 | .nf |
---|
19 | INCLUDE 'mpif.h' |
---|
20 | MPI_INIT(\fIREQUIRED, PROVIDED, IERROR\fP) |
---|
21 | INTEGER \fIREQUIRED, PROVIDED, IERROR\fP |
---|
22 | |
---|
23 | .SH C++ Syntax |
---|
24 | .nf |
---|
25 | #include <mpi.h> |
---|
26 | int MPI::Init_thread(int& \fIargc\fP, char**& \fIargv\fP, int \fIrequired\fP) |
---|
27 | int MPI::Init_thread(int \fIrequired\fP) |
---|
28 | |
---|
29 | .SH INPUT PARAMETERS |
---|
30 | .ft R |
---|
31 | .TP 1i |
---|
32 | argc |
---|
33 | C/C++ only: Pointer to the number of arguments. |
---|
34 | .TP 1i |
---|
35 | argv |
---|
36 | C/C++ only: Argument vector. |
---|
37 | .TP 1i |
---|
38 | required |
---|
39 | Desired level of thread support (integer). |
---|
40 | |
---|
41 | .SH OUTPUT PARAMETERS |
---|
42 | .ft R |
---|
43 | .TP 1i |
---|
44 | provided |
---|
45 | Available level of thread support (integer). |
---|
46 | .TP 1i |
---|
47 | IERROR |
---|
48 | Fortran only: Error status (integer). |
---|
49 | |
---|
50 | .SH DESCRIPTION |
---|
51 | .ft R |
---|
52 | This routine, or MPI_Init, must be called before any other MPI routine |
---|
53 | (apart from MPI_Initialized) is called. MPI can be initialized at most |
---|
54 | once; subsequent calls to MPI_Init or MPI_Init_thread are erroneous. |
---|
55 | .sp |
---|
56 | MPI_Init_thread, as compared to MPI_Init, has a provision to request a |
---|
57 | certain level of thread support in \fIrequired\fP: |
---|
58 | .TP 2.4i |
---|
59 | MPI_THREAD_SINGLE |
---|
60 | Only one thread will execute. |
---|
61 | .TP 2.4i |
---|
62 | MPI_THREAD_FUNNELED |
---|
63 | If the process is multithreaded, only the thread that called |
---|
64 | MPI_Init_thread will make MPI calls. |
---|
65 | .TP 2.4i |
---|
66 | MPI_THREAD_SERIALIZED |
---|
67 | If the process is multithreaded, only one thread will make MPI library |
---|
68 | calls at one time. |
---|
69 | .TP 2.4i |
---|
70 | MPI_THREAD_MULTIPLE |
---|
71 | If the process is multithreaded, multiple threads may call MPI at once |
---|
72 | with no restrictions. |
---|
73 | .SH |
---|
74 | The level of thread support available to the program is set in |
---|
75 | \fIprovided\fP, except in C++, where it is the return value of the |
---|
76 | function. In Open MPI, the value is dependent on how the library was configured and built. Note that there is no guarantee that \fIprovided\fP will be greater than or equal to |
---|
77 | \fIrequired\fP. |
---|
78 | .sp |
---|
79 | All MPI programs must contain a call to MPI_Init or |
---|
80 | MPI_Init_thread. Open MPI accepts the C/C++ \fIargc\fP and \fIargv\fP |
---|
81 | arguments to main, but neither modifies, interprets, nor distributes |
---|
82 | them: |
---|
83 | .sp |
---|
84 | .nf |
---|
85 | { |
---|
86 | /* declare variables */ |
---|
87 | MPI_Init_thread(&argc, &argv, req, &prov); |
---|
88 | /* parse arguments */ |
---|
89 | /* main program */ |
---|
90 | MPI_Finalize(); |
---|
91 | } |
---|
92 | .fi |
---|
93 | |
---|
94 | .SH NOTES |
---|
95 | .ft R |
---|
96 | The Fortran version does not have provisions for \fIargc\fP and |
---|
97 | \fIargv\fP and takes only IERROR. |
---|
98 | .sp |
---|
99 | It is the caller's responsibility to check the value of \fIprovided\fP, |
---|
100 | as it may be less than what was requested in \fIrequired\fP. |
---|
101 | .sp |
---|
102 | The MPI Standard does not say what a program can do before an |
---|
103 | MPI_Init_thread or after an MPI_Finalize. In the Open MPI |
---|
104 | implementation, it should do as little as possible. In particular, |
---|
105 | avoid anything that changes the external state of the program, such as |
---|
106 | opening files, reading standard input, or writing to standard output. |
---|
107 | |
---|
108 | .SH ERRORS |
---|
109 | .ft R |
---|
110 | Almost all MPI routines return an error value; C routines as |
---|
111 | the value of the function and Fortran routines in the last argument. C++ |
---|
112 | functions do not return errors. If the default error handler is set to |
---|
113 | MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism |
---|
114 | will be used to throw an MPI:Exception object. |
---|
115 | .sp |
---|
116 | Before the error value is returned, the current MPI error handler is |
---|
117 | called. By default, this error handler aborts the MPI job, except for |
---|
118 | I/O function errors. The error handler may be changed with |
---|
119 | MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN |
---|
120 | may be used to cause error values to be returned. Note that MPI does not |
---|
121 | guarantee that an MPI program can continue past an error. |
---|
122 | |
---|
123 | .SH SEE ALSO |
---|
124 | .ft R |
---|
125 | .nf |
---|
126 | MPI_Init |
---|
127 | MPI_Initialized |
---|
128 | MPI_Finalize |
---|
129 | |
---|