Hi Hui, Joachim, Thanks for the information. I am not able to find in the internet a clear example as to how to populate MPI_Info and use it with MPI_Comm_accept. I tried to do the following, but this is giving errors as shown below. Could you provide a small example to set up a timeout with MPI_Comm_accept? Do I need to populate port info too with MPI_Info? MPI_Init(NULL, NULL); char portName[MPI_MAX_PORT_NAME]; MPI_Open_port(MPI_INFO_NULL, portName); MPI_Info info; MPI_Info_create( &info ); MPI_Info_set(info, "timeout", "2"); MPI_Comm intercomm; MPI_Comm_accept(portName, info, 0, MPI_COMM_SELF, &intercomm); Error: $ ./server Waiting to accept.... Abort(671693606) on node 0 (rank 0 in comm 0): Fatal error in internal_Comm_accept: Invalid port, error stack: internal_Comm_accept(102)....: MPI_Comm_accept(port_name=tag#0$connentry#020098ADAC1785B70000000000000000$, info=0x9c000002, 0, MPI_COMM_SELF, newcomm=0x7f79b17dbcb8) failed MPID_Comm_accept(442)........: dynamic_intercomm_create(400): peer_intercomm_create(334)...: (unknown)(): Invalid port Regards, Rupsa On Fri, Jan 28, 2022 at 8:47 PM Joachim Protze <[email protected]> wrote:

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-s...

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(); }|

_______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss

-- Dr. rer. nat. Joachim Protze

IT Center Group: High Performance Computing Division: Computational Science and Engineering RWTH Aachen University Seffenter Weg 23 D 52074 Aachen (Germany) Tel: +49 241 80- 24765 Fax: +49 241 80-624765 [email protected] www.itc.rwth-aachen.de