This warning will go away if you change the code to: ierr = MPI_Allreduce(&lamx, &lambdax, 1, MPI_DOUBLE, MPI_MAX, PETSC_COMM_WORLD);CHKERRQ(ierr);
And its best to run code in gdb or valgrind to track down the crash. Satish On Tue, 18 Sep 2018, Jed Brown wrote: > Which compiler version are you using? This warning is harmless, but we > should still clean up these macros to avoid the warning. > > Praveen C <[email protected]> writes: > > > Dear all > > > > I use MPI_Allreduce in my petsc code and when compiling I see this type of > > messages > > > > /home/soft/include/petsclog.h:376:57: warning: value computed is not used > > [-Wunused-value] > > ((petsc_allreduce_ct += PetscMPIParallelComm(comm),0) || > > MPI_Allreduce(sendbuf,recvbuf,count,datatype,op,comm)) > > ^ > > fdweno.c:564:4: note: in expansion of macro ‘MPI_Allreduce’ > > MPI_Allreduce(&lamx, &lambdax, 1, MPI_DOUBLE, MPI_MAX, > > PETSC_COMM_WORLD); > > ^~~~~~~~~~~~~ > > > > This is with petsc-3.8.3 on Linux. > > > > My code crashes due to this error I think, > > This is certainly not why the code crashes. > > > while I dont get this problem on my macbook which uses petsc-3.9.0 > > > > Since the error is pointing to petsclog.h I thought I will ask here. > > > > Thanks > > praveen >
