1MPI_Init_thread(3) LAM/MPI MPI_Init_thread(3)
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6 MPI_Init_thread - Initialize the MPI execution environment
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9 #include <mpi.h>
10 int
11 MPI_Init_thread(int *pargc, char ***pargv, int requested, int *pprovided)
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14 pargc - Pointer to the number of arguments
15 pargv - Pointer to the argument vector
16 requested
17 - Desired level of thread support
18 pprovided
19 - Given level of thread support
20
23 LAM currently supports MPI_THREAD_SINGLE , MPI_THREAD_SERIALIZED , and
24 MPI_THREAD_FUNNELED . MPI_THREAD_MULTIPLE is not yet supported. The
25 use of MPI_INIT_THREAD is recommended instead of MPI_INIT if an MPI
26 program is going to be multi-threaded. However, the
27 LAM_MPI_THREAD_LEVEL environment variable can be used to the same
28 effect. See MPI_Init(3) for more details.
29 There is currently no distinction between MPI_THREAD_SINGLE and
31 MPI_THREAD_FUNNELED . An application using MPI_THREAD_FUNNELED prom‐
32 ises to never call MPI from a different thread than the one that
33 invoked MPI_INIT (or MPI_INIT_THREAD ). LAM does no checking to ensure
34 that this is true. As such, no locks are placed around MPI calls to
35 ensure that only one thread is making MPI calls at a time (since the
36 application has promised that only one thread will be making MPI
37 calls).
38 Using MPI_THREAD_SERIALIZED will cause LAM to place locks around all
40 MPI calls such that only one thread will be able to enter the MPI
41 library at a time; beware of this fact for portability with other MPI
42 implementations. Even with multiple threads, deadlock is still possi‐
43 ble when using MPI_THREAD_SERIALIZED -- applications still need to be
44 aware of this and code appropriately.
45 Other than this restriction, this function behaves identically to
47 MPI_INIT (see MPI_Init(3)).
48 Note that both MPI_INIT and MPI_INIT_THREAD are allowed to changed the
50 requested thread level based on lower-level device and SSI module ini‐
51 tializations. For example, if a user application invokes MPI_Init ,
52 some SSI modules may require threads and therefore upgrade the thread
53 support level to something higher than MPI_THREAD_SINGLE .
54
58 If an error occurs in an MPI function, the current MPI error handler is
59 called to handle it. By default, this error handler aborts the MPI
60 job. The error handler may be changed with MPI_Errhandler_set ; the
61 predefined error handler MPI_ERRORS_RETURN may be used to cause error
62 values to be returned (in C and Fortran; this error handler is less
63 useful in with the C++ MPI bindings. The predefined error handler
64 MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value
65 needs to be recovered). Note that MPI does not guarantee that an MPI
66 program can continue past an error.
67 All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
69 value; C routines as the value of the function and Fortran routines in
70 the last argument. The C++ bindings for MPI do not return error val‐
71 ues; instead, error values are communicated by throwing exceptions of
72 type MPI::Exception (but not by default). Exceptions are only thrown
73 if the error value is not MPI::SUCCESS .
74 Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI
77 functions will return upon an error, there will be no way to recover
78 what the actual error value was.
79 MPI_SUCCESS
80 - No error; MPI routine completed successfully.
81 MPI_ERR_ARG
82 - Invalid argument. Some argument is invalid and is not identi‐
83 fied by a specific error class. This is typically a NULL
84 pointer or other such error.
85 MPI_ERR_OTHER
86 - This error class is associated with an error code that indi‐
87 cates that an attempt was made to call MPI_INIT a second time.
88 MPI_INIT may only be called once in a program.
89 MPI_ERR_OTHER
90 - Other error; use MPI_Error_string to get more information
91 about this error code.
92
95 MPI_Init, MPI_Finalize, lamboot, mpirun, lamhalt, lamssi
96
99 For more information, please see the official MPI Forum web site, which
100 contains the text of both the MPI-1 and MPI-2 standards. These docu‐
101 ments contain detailed information about each MPI function (most of
102 which is not duplicated in these man pages).
103 http://www.mpi-forum.org/
105
109 The LAM Team would like the thank the MPICH Team for the handy program
110 to generate man pages ("doctext" from ftp://ftp.mcs.anl.gov/pub/sow‐
111 ing/sowing.tar.gz ), the initial formatting, and some initial text for
112 most of the MPI-1 man pages.
113
115 initthr.c
116LAM/MPI 7.1.2 2/23/2006 MPI_Init_thread(3)