Hi, since you have a separate thread for the accept, you could just set a flag at the main thread, open a connection from the main thread to match the accept. The accept thread sees the flag, immediately closes the connection and leaves the while loop. - Joachim Am 28.01.22 um 05:54 schrieb Rupsa Chakraborty via discuss:

Hello,

I am asking this question in this forum as I had already asked this question in stack overflow and did not receive any answer/comment: https://stackoverflow.com/questions/70745740/how-to-gracefully-exit-an-mpi-s... <https://stackoverflow.com/questions/70745740/how-to-gracefully-exit-an-mpi-server-process-when-it-is-waiting-on-mpi-comm-acce>

My concern is as follows: I have an MPI server program that calls MPI_Comm_accept, in an infinite loop, on a separate thread. The main thread spawns this thread and in parallel does some other work. At some point of time the main thread decides to exit. It closes the port using MPI_Close_port(portName), however the MPI_Comm_accept() is still waiting for connection requests.

My question is: - How does the main thread exit gracefully? Is there an equivalent of socket close in MPI? I am using mpich which I can use from main thread?

- Is there anyway I can set timeout to the MPI_Comm_accept call?

Here is a dummy code that looks similar to my server code:

|// MPI Server Program void accept(std::string portName) { while (true) { MPI_Comm intercomm; MPI_Comm_accept(portName.c_str(), MPI_INFO_NULL, 0, MPI_COMM_SELF, &intercomm); // handle connection MPI_Comm_disconnect(&intercomm); } } int main() { char ch; MPI_Init(NULL, NULL); char portName[MPI_MAX_PORT_NAME]; MPI_Open_port(MPI_INFO_NULL, portName); publishName("nameServerFile.txt", "ocean", std::string(portName)); std::thread th(&accept, std::string(portName)); // do something MPI_Close_port(portName); std::cout <<"\nClosed port" << std::endl; th.join(); // main thread waits infinitely at this join // as child thread is still waiting on MPI_Comm_accept MPI_Finalize(); }|

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