# Six calls to sends and receives have been removed from the # code below, and you must add back the appropriate sends and # receives with the appropriate arguments at sites marked by: # ## MISSING...

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# Six calls to sends and receives have been removed from the # code below, and you must add back the appropriate sends and # receives with the appropriate arguments at sites marked by: # ## MISSING IPC CALL # # At each site, a call to an MPI send or receive function is # needed with two aruments, the first being the message array # object that is being sent or received and the second being # a specification of the communicating partner: # #comm.Send( ____, dest=____ ) # # or # #comm.Recv( ____, source=____ ) # # Note that the server must be able to receive from any client. # This is an example of the "select" functionality described in # section 3.4.2. The ability for a server to select a message # from any client is easy to code with MPI in Python. See # https://nyu-cds.github.io/python-mpi/02-messagepassing/ for # a tutorial on MPI blocking sends and receives in Python. # # Example command line to run this program: # #mpiexec -n 3 python mpi3.py # # (the number of processes given by -n should be 2 or more) # # The server process has rank 0. It maintains a sum variable, # which it updates based on requests from clients. The server # will also receive completion messages from clients and will # terminate when all the clients have completed. # # The client processes have ranks 1 and above, which are used as # the client numbers. A client process sends an update request # and then waits on an acknowledgement reply from the server. # After a given number of update requests, each client sends a # completion message to the server and then waits on an # acknowledgement reply from the server. # # The update message format from a client to the server is: # #[ ] # # (where value == 0 is used as a sentinel value for completion) # # All requests are acknowledged by the server in a reply message. # The reply message format from the server is: # #[ 0 1 ] # # Note that all messages start with the rank of the process that # is sending the message. This message protocol allows the # server process to know the identity of the requesting client # when a request is selected by the server's call to the MPI # receive function. # # numpy is used for more efficient numeric arrays. import numpy from mpi4py import MPI comm = MPI.COMM_WORLD rank = comm.Get_rank() num_clients = comm.Get_size() - 1 if num_clients <= 0:="" print="" 'command="" line="" argument="" does="" not="" allow="" clients'="" raise="" systemexit="" #="" client="" code="" if="" rank="" !="0:" request="numpy.zeros(" 2,="" dtype='i' )="" reply="numpy.zeros(" 2,="" dtype='i' )="" for="" i="" in="" range(="" 1,="" 3="" ):="" request[0]="rank" request[1]="i" *="" rank="" #="" missing="" ipc="" call="" #="" for="" update="" request="" #="" missing="" ipc="" call="" #="" for="" reply="" print="" 'client',="" rank,="" 'received="" acknowledgement'="" request[0]="rank" request[1]="0" #="" missing="" ipc="" call="" #="" for="" completion="" notice="" #="" missing="" ipc="" call="" #="" for="" reply="" print="" 'client',="" rank,="" 'done'="" #="" server="" code="" else:="" print="" 'simple="" server="" with',="" num_clients,="" 'clients'="" sum="0" print="" 'server="" starts="" with="" a="" sum="" value="" of',="" sum="" service_request="numpy.zeros(" 2,="" dtype='i' )="" acknowledgement="numpy.zeros(" 2,="" dtype='i' )="" acknowledgement[0]="0" acknowledgement[1]="1" while="" num_clients=""> 0: # MISSING IPC CALL if service_request[1] != 0: print 'server received update from client', print service_request[0] sum += service_request[1] print 'server added', service_request[1], print 'and sum is now', sum else: print 'server receives completion notice', print 'from client', service_request[0] num_clients -= 1 # MISSING IPC CALL print 'server done'