what is the difference between send and isend in message passing interface (MPI)

Question

I am learning MPI, but i do not know exactly how they are different.

Could someone explain to me what are the differences between MPI_Send an MPI_Isend, please?

Possible duplicate of [mpi: blocking vs non-blocking](https://stackoverflow.com/questions/10017301/mpi-blocking-vs-non-blocking) — Wesley Bland, Jan 17 '18 at 19:35

score 1 · Accepted Answer · answered Jan 15 '18 at 15:45

MPI_Send() blocks until the send buffer can be modified.

From a pragmatic point of view, MPI_Send() of a large message blocks until it is received. Though MPI_Send() of a short message might return immediately, a correctly written MPI application should never expect MPI_Send() returns before the message is received.

MPI_Isend() returns immediately, and the send buffer cannot be modified until the issued request completes.

what is the difference between send and isend in message passing interface (MPI)

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