Difference between revisions of "Fortran implementation of the Actor Model using MPI"
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| − | A very simple ping-pong program is shown here. There are 2 programs, ''[[ping]]'' and ''[[pong]]'', that shoot messages among them, starting each with a random number of plays. The first program reaching 0 will send a message for the other program to stop and stops itself. File moduleMPImanagement is necessary to compile both programs. | + | A very simple ping-pong program is shown here. There are 2 programs, ''[[ping]]'' and ''[[pong]]'', that shoot messages among them, starting each with a random number of plays. The first program reaching 0 will send a message for the other program to stop and stops itself. File ''[[moduleMPImanagement]]'' is necessary to compile both programs. |
| + | |||
| + | If you examine the code there is no single MPI_BARRIER or any other explicit synchronization point. The main subroutine is: | ||
| + | |||
| + | subroutine main() | ||
| + | type(T_pingPong), pointer :: pingPong | ||
| + | integer :: STAT_CALL | ||
| + | STAT_CALL = UNDEFINED | ||
| + | pingPong => constructPingPong() | ||
| + | STAT_CALL = startGame(pingPong) | ||
| + | if (STAT_CALL .NE. SUCCESS) then | ||
| + | print*, "STAT_CALL = ", STAT_CALL | ||
| + | stop "subroutine main, error calling startGame, ERR01" | ||
| + | end if | ||
| + | call loop(pingPong) !This loop reads MPI messages | ||
| + | call EXIT(SUCCESS) | ||
| + | end subroutine main | ||
| + | |||
| + | There is a call to an infinite loop. This routine reads the MPI message queue identifying messages to itself (MPI_PROBE). | ||
| + | |||
| + | recursive subroutine loop(pingPong) | ||
| + | type(T_pingPong), pointer :: pingPong | ||
| + | integer :: STAT_CALL | ||
| + | integer :: STATUS(MPI_STATUS_SIZE) | ||
| + | STAT_CALL = UNDEFINED | ||
| + | call MPI_PROBE(MPI_ANY_SOURCE, & | ||
| + | MPI_ANY_TAG, & | ||
| + | MPI_COMM_WORLD, & | ||
| + | STATUS, & | ||
| + | STAT_CALL) | ||
| + | if (STAT_CALL .NE. SUCCESS) then | ||
| + | print*, "STAT_CALL = ", STAT_CALL | ||
| + | stop "subroutine loop, error calling MPI_PROBE, ERR01" | ||
| + | end if | ||
| + | if (STATUS(MPI_SOURCE) .EQ. getOtherMPI_id(pingPong)) then | ||
| + | if (STATUS(MPI_TAG) .EQ. getMsgPlayBall3Tag()) then | ||
| + | STAT_CALL = receiveBall(pingPong, STATUS(MPI_TAG)) | ||
| + | if (STAT_CALL .NE. SUCCESS) then | ||
| + | print*, "STAT_CALL = ", STAT_CALL | ||
| + | stop "subroutine loop, error calling receiveBall, ERR02" | ||
| + | end if | ||
| + | else if (STATUS(MPI_TAG) .EQ. getMsgEndGameTag()) then | ||
| + | STAT_CALL = killPingPong(pingPong) | ||
| + | if (STAT_CALL .NE. SUCCESS) then | ||
| + | print*, "STAT_CALL = ", STAT_CALL | ||
| + | stop "subroutine main, error calling killPingPong, ERR02" | ||
| + | end if | ||
| + | end if | ||
| + | end if | ||
| + | if (pingPong%gameON) call loop(pingPong) | ||
| + | end subroutine loop | ||
| + | |||
| + | In the recursive subroutine loop 2 messages are processed: getMsgPlayBall3Tag and getMsgEndGameTag. As promised by the actor model: | ||
| + | *internal state is encapsulated; | ||
| + | *messages are processed one at a time; and | ||
| + | *communication is asynchronous. | ||
Latest revision as of 18:54, 30 November 2014
A very simple ping-pong program is shown here. There are 2 programs, ping and pong, that shoot messages among them, starting each with a random number of plays. The first program reaching 0 will send a message for the other program to stop and stops itself. File moduleMPImanagement is necessary to compile both programs.
If you examine the code there is no single MPI_BARRIER or any other explicit synchronization point. The main subroutine is:
subroutine main()
type(T_pingPong), pointer :: pingPong
integer :: STAT_CALL
STAT_CALL = UNDEFINED
pingPong => constructPingPong()
STAT_CALL = startGame(pingPong)
if (STAT_CALL .NE. SUCCESS) then
print*, "STAT_CALL = ", STAT_CALL
stop "subroutine main, error calling startGame, ERR01"
end if
call loop(pingPong) !This loop reads MPI messages
call EXIT(SUCCESS)
end subroutine main
There is a call to an infinite loop. This routine reads the MPI message queue identifying messages to itself (MPI_PROBE).
recursive subroutine loop(pingPong)
type(T_pingPong), pointer :: pingPong
integer :: STAT_CALL
integer :: STATUS(MPI_STATUS_SIZE)
STAT_CALL = UNDEFINED
call MPI_PROBE(MPI_ANY_SOURCE, &
MPI_ANY_TAG, &
MPI_COMM_WORLD, &
STATUS, &
STAT_CALL)
if (STAT_CALL .NE. SUCCESS) then
print*, "STAT_CALL = ", STAT_CALL
stop "subroutine loop, error calling MPI_PROBE, ERR01"
end if
if (STATUS(MPI_SOURCE) .EQ. getOtherMPI_id(pingPong)) then
if (STATUS(MPI_TAG) .EQ. getMsgPlayBall3Tag()) then
STAT_CALL = receiveBall(pingPong, STATUS(MPI_TAG))
if (STAT_CALL .NE. SUCCESS) then
print*, "STAT_CALL = ", STAT_CALL
stop "subroutine loop, error calling receiveBall, ERR02"
end if
else if (STATUS(MPI_TAG) .EQ. getMsgEndGameTag()) then
STAT_CALL = killPingPong(pingPong)
if (STAT_CALL .NE. SUCCESS) then
print*, "STAT_CALL = ", STAT_CALL
stop "subroutine main, error calling killPingPong, ERR02"
end if
end if
end if
if (pingPong%gameON) call loop(pingPong)
end subroutine loop
In the recursive subroutine loop 2 messages are processed: getMsgPlayBall3Tag and getMsgEndGameTag. As promised by the actor model:
- internal state is encapsulated;
- messages are processed one at a time; and
- communication is asynchronous.
