[MPICH] MPI Implementation Problems

[ashish kabra]

Hii 

 I am novice in mpi programming 
 
I have some mpi implementation problems 


• i have one non ending loop which blocks to get
clients data in some "buffer"
  then some set of non-blocking MPI_ISends and
MPI_IRecvs that modify "buffer"
  
  finally i want to send that modified buffer back to
client.

 But the problem is when any of last non blocking
receive is completed that should be traced and the
correct data should be send to corresponding client ..

 i just want many concurrent clients to be served
without blocking for the result. when the    result is
ready it should be sent to correct client .

pseudo code can be like this

while(1)
{
   client_sockfd=accept(....); // blocking

   recv(client_sockfd,buffer,bufsize,0); // Blocking
call
  
   MPI_Isend(buffer,bufsize,...);
   MPI_Irecv(buffer,bufsize,..);
   MPI_Isend(buffer,bufsize,...;)

   MPI_Irecv(buffer,bufsize,..);

 (( what MPI_Test ??? ))

  if ( flag==true)
   send(client_sockfd,buffer);   //blocking call

}

i just don't want to block for any operation except
accept,recv, & send ..

without putting MPI_Wait in code.

 when that result is ready to send in buffer .. it
shud b sent to corresponding client

 
 How to solve this ??

• Another problem is there are some non-blocking sends
and receives ..

when any one of those non blocking call fails .. i.e
process fails to complete ..call ..

Corresponding  non blocking send / receive needs
canceled and i want to trace which process failed ..
without exiting the from process giving error..

How can i know which process failed


• Fork creats child with same rank in communication
world any other issues.. How MPI_send receive will be
handled by both process as they have same RANK ??
 can anybody explains MPI "threads" of same
environment 

•  Can a process created later ..join the pool of mpi
processes in some communication world.
 
please tell me the possible solutions to these
problems 
Thanks in advance.

 ashish

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