1MPI_Waitsome(3) LAM/MPI MPI_Waitsome(3)
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6 MPI_Waitsome - Waits for some given communications to complete
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9 #include <mpi.h>
10 int MPI_Waitsome(int count, MPI_Request* reqs, int *ndone,
11 int *indices, MPI_Status *stats)
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14 incount
15 - length of array_of_requests (integer)
16 reqs - array of requests (array of handles)
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20 ndone - number of completed requests (integer)
21 indices
22 - array of indices of operations that completed (array of inte‐
23 gers)
24 stats - array of status objects for operations that completed (array
25 of Status), or the MPI constant MPI_STATUSES_IGNORE
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30 The array of indicies are in the range 0 to incount - 1 for C and in
31 the range 1 to incount for Fortran.
32 Null requests are ignored; if all requests are null, then the routine
34 returns with outcount set to MPI_UNDEFINED .
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39 For send operations, the only use of status is for MPI_Test_cancelled
40 in the case that there is an error, in which case the MPI_ERROR field
41 of status will be set.
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45 All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
46 an additional argument ierr at the end of the argument list. ierr is
47 an integer and has the same meaning as the return value of the routine
48 in C. In Fortran, MPI routines are subroutines, and are invoked with
49 the call statement.
50 All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
52 Fortran.
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56 If an error occurs in an MPI function, the current MPI error handler is
57 called to handle it. By default, this error handler aborts the MPI
58 job. The error handler may be changed with MPI_Errhandler_set ; the
59 predefined error handler MPI_ERRORS_RETURN may be used to cause error
60 values to be returned (in C and Fortran; this error handler is less
61 useful in with the C++ MPI bindings. The predefined error handler
62 MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value
63 needs to be recovered). Note that MPI does not guarantee that an MPI
64 program can continue past an error.
65 All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
67 value; C routines as the value of the function and Fortran routines in
68 the last argument. The C++ bindings for MPI do not return error val‐
69 ues; instead, error values are communicated by throwing exceptions of
70 type MPI::Exception (but not by default). Exceptions are only thrown
71 if the error value is not MPI::SUCCESS .
72 Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI
75 functions will return upon an error, there will be no way to recover
76 what the actual error value was.
77 MPI_SUCCESS
78 - No error; MPI routine completed successfully.
79 MPI_ERR_REQUEST
80 - Invalid MPI_Request ; either null or, MPI_REQUEST_NULL , in
81 the case of a MPI_Start or MPI_Startall , not a persistent
82 request.
83 MPI_ERR_COUNT
84 - Invalid count argument. Count arguments must be non-negative;
85 a count of zero is often valid.
86 MPI_ERR_ARG
87 - Invalid argument. Some argument is invalid and is not identi‐
88 fied by a specific error class. This is typically a NULL
89 pointer or other such error.
90 MPI_ERR_IN_STATUS
92 - The actual error value is in the MPI_Status argument. Note
93 that if this error occurs and MPI_STATUS_IGNORE or MPI_STA‐
94 TUSES_IGNORE was used as the status argument, the actual error
95 will be lost. This error class is returned only from the multi‐
96 ple-completion routines ( MPI_Testall , MPI_Testany , MPI_Test‐
97 some , MPI_Waitall , MPI_Waitany , and MPI_Waitsome ). The
98 field MPI_ERROR in the status argument contains the error value
99 or MPI_SUCCESS (no error and complete) or MPI_ERR_PENDING to
100 indicate that the request has not completed. The MPI Standard
101 does not specify what the result of the multiple completion rou‐
102 tines is when an error occurs. For example, in an MPI_WAITALL ,
103 does the routine wait for all requests to either fail or com‐
104 plete, or does it return immediately (with the MPI definition of
105 immediately, which means independent of actions of other MPI
106 processes)? LAM/MPI has chosen to make the return immediate
107 (alternately, local in MPI terms), and to use the error class
108 MPI_ERR_PENDING (introduced in MPI 1.1) to indicate which
109 requests have not completed. In most cases, only one request
110 with an error will be detected in each call to an MPI routine
111 that tests multiple requests. The requests that have not been
112 processed (because an error occured in one of the requests) will
113 have their MPI_ERROR field marked with MPI_ERR_PENDING .
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118 For more information, please see the official MPI Forum web site, which
119 contains the text of both the MPI-1 and MPI-2 standards. These docu‐
120 ments contain detailed information about each MPI function (most of
121 which is not duplicated in these man pages).
122 http://www.mpi-forum.org/
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128 The LAM Team would like the thank the MPICH Team for the handy program
129 to generate man pages ("doctext" from ftp://ftp.mcs.anl.gov/pub/sow‐
130 ing/sowing.tar.gz ), the initial formatting, and some initial text for
131 most of the MPI-1 man pages.
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134 waitsome.c
135LAM/MPI 7.1.2 2/23/2006 MPI_Waitsome(3)