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</o:shapelayout></xml><![endif]--></head><body lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi Florin,<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I don’t think you’re hitting any bug, and I’d say both behaviors are correct. Note that when you do a sleep the MPI implementation is not making any progress, so if the Isend call didn’t push the message immediately to the network, which is likely to be more the case on an HPC network than on a socket-based one, the sleep is unproductive, and so the Iprobe returns nothing arrived.<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Best,<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> Toni<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--------------------------------------------------------------<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Antonio J. Peņa<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Postdoctoral Appointee<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Mathematics and Computer Science Division (MCS)<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Argonne National Laboratory<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">9700 S. Cass Avenue<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Argonne, IL 60439<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Building 340 - Office 3148<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">apenya@mcs.anl.gov<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(+1) 630-252-7928<o:p></o:p></span></p></div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Isaila, Florin D. [mailto:fisaila@mcs.anl.gov] <br><b>Sent:</b> Thursday, November 20, 2014 4:20 PM<br><b>To:</b> mpich-discuss@mcs.anl.gov<br><b>Subject:</b> [mpich-discuss] MPI_Iprobe bug in MPICH for BGQ?<o:p></o:p></span></p></div></div><p class="MsoNormal"><o:p> </o:p></p><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Hi, <br><br>when I run the program from below on 1 node on BGQ (Vesta), the message is not received (flag is 0). However on a Ubuntu, the message is received (flag is non-zero). <br><br>If I add another Iprobe (uncomment the Iprobe in the code below) the message is received on both BGQ and Ubuntu. Note that the program sleeps for 1 second after the Isend. Is it a bug? <br><br>This happens for both MPICH-3.1.3 and MPICH-3.1.<br><br><br>#include "mpi.h"<br>#include <stdio.h><br>#include <unistd.h><br><br>int main(int argc, char **argv)<br>{<br> int send_int, recv_int, tag, flag;<br> MPI_Status status;<br> MPI_Request req;<br><br> MPI_Init(&argc, &argv);<br><br> tag = 0;<br> send_int = 100;<br> MPI_Isend(&send_int, 1, MPI_INT, 0, tag, MPI_COMM_WORLD, &req );<br> sleep(1);<br><br> MPI_Iprobe(MPI_ANY_SOURCE , MPI_ANY_TAG, MPI_COMM_WORLD, &flag, &status );<br> //MPI_Iprobe(MPI_ANY_SOURCE , tag, MPI_COMM_WORLD, &flag, &status );<br> if (flag) {<br> MPI_Recv( &recv_int, 1, MPI_INT, MPI_ANY_SOURCE, tag, MPI_COMM_WORLD, &status);<br> printf("Received = %d\n", recv_int);<br> }<br> else<br> printf("Message not received yet");<br><br> MPI_Waitall(1, &req, MPI_STATUSES_IGNORE);<br><br> MPI_Finalize();<br> return 0;<br>}<br><br>Thanks<br>Florin<o:p></o:p></span></p></div></div></body></html>