1 | .\"Copyright 2006-2008 Sun Microsystems, Inc. |
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2 | .\" Copyright (c) 1996 Thinking Machines Corporation |
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3 | .TH MPI_Testsome 3 "Dec 08, 2009" "1.4" "Open MPI" |
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4 | .SH NAME |
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5 | \fBMPI_Testsome\fP \- Tests for completion of one or more previously initiated communications in a list. |
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6 | |
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7 | .SH SYNTAX |
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8 | .ft R |
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9 | .SH C Syntax |
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10 | .nf |
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11 | #include <mpi.h> |
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12 | int MPI_Testsome(int \fIincount\fP, MPI_Request \fI*array_of_requests\fP, |
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13 | int\fI *outcount\fP, int\fI *array_of_indices\fP, MPI_Status\fI *array_of_statuses\fP) |
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14 | |
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15 | .SH Fortran Syntax |
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16 | .nf |
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17 | INCLUDE 'mpif.h' |
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18 | MPI_TESTSOME(\fIINCOUNT, ARRAY_OF_REQUESTS, OUTCOUNT, |
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19 | ARRAY_OF_INDICES, ARRAY_OF_STATUSES, IERROR\fP) |
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20 | INTEGER \fIINCOUNT, ARRAY_OF_REQUESTS(*)\fP |
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21 | INTEGER \fIOUTCOUNT, ARRAY_OF_INDICES(*)\fP |
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22 | INTEGER \fIARRAY_OF_STATUSES(MPI_STATUS_SIZE,*), IERROR\fP |
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23 | |
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24 | .SH C++ Syntax |
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25 | .nf |
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26 | #include <mpi.h> |
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27 | static int Request::Testsome(int \fIincount\fP, Request |
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28 | \fIarray_of_requests\fP[], int \fIarray_of_indices\fP[], Status \fIarray_of_statuses\fP[]) |
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29 | |
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30 | static int Request::Testsome(int \fIincount\fP, Request |
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31 | \fIarray_of_requests\fP[], int \fIarray_of_indices\fP[]) |
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32 | |
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33 | .SH INPUT PARAMETERS |
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34 | .ft R |
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35 | .TP 1i |
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36 | incount |
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37 | Length of array_of_requests (integer). |
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38 | .TP 1i |
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39 | array_of_requests |
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40 | Array of requests (array of handles). |
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41 | |
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42 | .SH OUTPUT PARAMETERS |
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43 | .ft R |
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44 | .TP 1i |
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45 | outcount |
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46 | Number of completed requests (integer). |
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47 | .TP 1i |
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48 | array_of_indices |
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49 | Array of indices of operations that completed (array of integers). |
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50 | .TP 1i |
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51 | array_of_statuses |
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52 | Array of status objects for operations that completed (array of status). |
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53 | .ft R |
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54 | .TP 1i |
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55 | IERROR |
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56 | Fortran only: Error status (integer). |
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57 | |
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58 | .SH DESCRIPTION |
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59 | .ft R |
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60 | Behaves like MPI_Waitsome, except that it returns immediately. If no operation has completed it returns outcount = 0. If there is no active handle in the list, it returns outcount = MPI_UNDEFINED. |
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61 | .sp |
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62 | MPI_Testsome is a local operation, which returns immediately, whereas MPI_Waitsome blocks until a communication completes, if it was passed a list that contains at least one active handle. Both calls fulfill a fairness requirement: If a request for a receive repeatedly appears in a list of requests passed to MPI_Waitsome or MPI_Testsome, and a matching send has been posted, then the receive will eventually succeed unless the send is satisfied by another receive; send requests also fulfill this fairness requirement. |
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63 | .sp |
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64 | Errors that occur during the execution of MPI_Testsome are handled as for |
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65 | MPI_Waitsome. |
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66 | .sp |
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67 | If your application does not need to examine the \fIarray_of_statuses\fP field, you can save resources by using the predefined constant MPI_STATUSES_IGNORE can be used as a special value for the \fIarray_of_statuses\fP argument. |
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68 | |
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69 | .SH NOTES |
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70 | The use of MPI_Testsome is likely to be more |
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71 | efficient than the use of MPI_Testany. The former returns information on all completed communications; with the latter, a new call is required for each communication that completes. |
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72 | .sp |
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73 | A server with multiple clients can use MPI_Waitsome so as not to starve any client. Clients send messages to the server with service requests. The server calls MPI_Waitsome with one receive request for each client, then handles all receives that have completed. If a call to MPI_Waitany is used instead, then one client could starve while requests from another client always sneak in first. |
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74 | |
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75 | .SH ERRORS |
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76 | For each invocation of MPI_Testsome, if one or more requests generate |
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77 | an MPI exception, only the \fIfirst\fP MPI request that caused an |
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78 | exception will be passed to its corresponding error handler. No other |
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79 | error handlers will be invoked (even if multiple requests generated |
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80 | exceptions). However, \fIall\fP requests that generate an exception |
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81 | will have a relevant error code set in the corresponding |
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82 | status.MPI_ERROR field (unless MPI_IGNORE_STATUSES was used). |
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83 | .sp |
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84 | The default error handler aborts the MPI job, except for I/O function |
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85 | errors. The error handler may be changed with MPI_Comm_set_errhandler, |
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86 | MPI_File_set_errhandler, or MPI_Win_set_errhandler (depending on the |
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87 | type of MPI handle that generated the MPI request); the predefined |
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88 | error handler MPI_ERRORS_RETURN may be used to cause error values to |
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89 | be returned. Note that MPI does not guarantee that an MPI program can |
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90 | continue past an error. |
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91 | .sp |
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92 | If the invoked error handler allows MPI_Testsome to return to the |
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93 | caller, the value MPI_ERR_IN_STATUS will be returned in the C and |
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94 | Fortran bindings. In C++, if the predefined error handler |
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95 | MPI::ERRORS_THROW_EXCEPTIONS is used, the value MPI::ERR_IN_STATUS |
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96 | will be contained in the MPI::Exception object. The MPI_ERROR field |
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97 | can then be examined in the array of returned statuses to determine |
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98 | exactly which request(s) generated an exception. |
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99 | |
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100 | .SH SEE ALSO |
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101 | .ft R |
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102 | .sp |
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103 | MPI_Comm_set_errhandler |
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104 | .br |
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105 | MPI_File_set_errhandler |
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106 | .br |
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107 | MPI_Test |
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108 | .br |
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109 | MPI_Testall |
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110 | .br |
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111 | MPI_Testany |
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112 | .br |
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113 | MPI_Wait |
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114 | .br |
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115 | MPI_Waitall |
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116 | .br |
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117 | MPI_Waitany |
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118 | .br |
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119 | MPI_Waitsome |
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120 | .br |
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121 | MPI_Win_set_errhandler |
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122 | .br |
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123 | |
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