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Thanks for reporting. We'll fix this. Tracking issue: <a href="https://github.com/pmodels/mpich/issues/5775" id="LPlnkOWALinkPreview">
https://github.com/pmodels/mpich/issues/5775</a><br>
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<a target="_blank" id="LPUrlAnchor383364" href="https://github.com/pmodels/mpich/issues/5775" style="text-decoration: none; color: var(--themePrimary);">ch4: MPI_Cancel stalls MPI_Wait · Issue #5775 · pmodels/mpich</a></div>
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Reported on discuss mailinglist: ---- quote ---- Hi, Running one of our test programs using MPICH 3.4.3 and ch4:ofi, I notice that MPI_Wait on an MPI_Request that has been MPI_Cancelled never compl...</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Edric Ellis via discuss <discuss@mpich.org><br>
<b>Sent:</b> Wednesday, January 19, 2022 11:21 AM<br>
<b>To:</b> discuss@mpich.org <discuss@mpich.org><br>
<b>Cc:</b> Edric Ellis <eellis@mathworks.com><br>
<b>Subject:</b> [mpich-discuss] MPI_Cancel + MPI_Wait stalls when using ch4, not when using ch3</font>
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<div class="PlainText">Hi,<br>
<br>
Running one of our test programs using MPICH 3.4.3 and ch4:ofi, I notice that MPI_Wait on an MPI_Request that has been MPI_Cancelled never completes (it does when using ch3). (The documentation for MPI_Cancel states "If a communication is marked for cancellation,
then a MPI_WAIT call for that communication is guaranteed to return, irrespective of the activities of other processes (i.e., MPI_WAIT behaves as a local function)")<br>
<br>
Here's a simple example:<br>
<br>
#include <mpi.h><br>
#include <stdio.h><br>
#include <stdlib.h><br>
<br>
void check(int const value) {<br>
if (value != MPI_SUCCESS) {<br>
fprintf(stderr, "Failed.\n");<br>
exit(1);<br>
}<br>
}<br>
<br>
int main(int argc, char** argv) {<br>
MPI_Request r1;<br>
int payload = 42;<br>
int result;<br>
<br>
check(MPI_Init(0,0));<br>
check(MPI_Issend(&payload, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, &r1));<br>
check(MPI_Test(&r1, &result, MPI_STATUS_IGNORE));<br>
fprintf(stdout, "MPI_Test result: %d\n", result);<br>
check(MPI_Cancel(&r1));<br>
check(MPI_Wait(&r1, MPI_STATUS_IGNORE));<br>
MPI_Finalize();<br>
return 0;<br>
}<br>
<br>
This stalls in MPI_Wait when executed using "mpiexec -n 1 ./a.out". <br>
<br>
Cheers,<br>
Edric.<br>
<br>
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