MPI_Testsome(3OpenMPI) MPI_Testsome(3OpenMPI)
NAME
MPI_Testsome - Tests for completion of one or more previously initiated communications in a list.
SYNTAX
C Syntax
#include <mpi.h> int MPI_Testsome(int incount, MPI_Request *array_of_requests, int *outcount, int *array_of_indices, MPI_Status *array_of_statuses)
Fortran Syntax
INCLUDE 'mpif.h' MPI_TESTSOME(INCOUNT, ARRAY_OF_REQUESTS, OUTCOUNT, ARRAY_OF_INDICES, ARRAY_OF_STATUSES, IERROR) INTEGER INCOUNT, ARRAY_OF_REQUESTS(*) INTEGER OUTCOUNT, ARRAY_OF_INDICES(*) INTEGER ARRAY_OF_STATUSES(MPI_STATUS_SIZE,*), IERROR
C++ Syntax
#include <mpi.h> static int Request::Testsome(int incount, Request array_of_requests[], int array_of_indices[], Status array_of_statuses[]) static int Request::Testsome(int incount, Request array_of_requests[], int array_of_indices[])
INPUT PARAMETERS
incount Length of array_of_requests (integer). array_of_requests Array of requests (array of handles).
OUTPUT PARAMETERS
outcount Number of completed requests (integer). array_of_indices Array of indices of operations that completed (array of inte- gers). array_of_statuses Array of status objects for operations that completed (array of status). IERROR Fortran only: Error status (integer).
DESCRIPTION
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. 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 match- ing 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. Errors that occur during the execution of MPI_Testsome are handled as for MPI_Waitsome. If your application does not need to examine the array_of_statuses field, you can save resources by using the predefined constant MPI_STA- TUSES_IGNORE can be used as a special value for the array_of_statuses argument.
NOTES
The use of MPI_Testsome is likely to be more efficient than the use of MPI_Testany. The former returns information on all completed communica- tions; with the latter, a new call is required for each communication that completes. 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.
ERRORS
For each invocation of MPI_Testsome, if one or more requests generate an MPI exception, only the first MPI request that caused an exception will be passed to its corresponding error handler. No other error han- dlers will be invoked (even if multiple requests generated exceptions). However, all requests that generate an exception will have a relevant error code set in the corresponding status.MPI_ERROR field (unless MPI_IGNORE_STATUSES was used). The default error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler, MPI_File_set_errhandler, or MPI_Win_set_errhandler (depending on the type of MPI handle that generated the MPI request); the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can con- tinue past an error. If the invoked error handler allows MPI_Testsome to return to the caller, the value MPI_ERR_IN_STATUS will be returned in the C and For- tran bindings. In C++, if the predefined error handler MPI::ERRORS_THROW_EXCEPTIONS is used, the value MPI::ERR_IN_STATUS will be contained in the MPI::Exception object. The MPI_ERROR field can then be examined in the array of returned statuses to determine exactly which request(s) generated an exception.
SEE ALSO
MPI_Comm_set_errhandler(3), MPI_File_set_errhandler(3), MPI_Test(3), MPI_Testall(3), MPI_Testany(3), MPI_Wait(3), MPI_Waitall(3), MPI_Waitany(3), MPI_Waitsome(3), MPI_Win_set_errhandler(3) Open MPI 1.2 September 2006 MPI_Testsome(3OpenMPI)
Mac OS X 10.6 - Generated Thu Sep 17 20:13:16 CDT 2009