The executable hangs with no MPI

[certik]

I use the following input file:

! Input from namelist
&invar
  npey=1
  npez=1
  ichunk=2
  nthreads=2
  nnested=1
  ndimen=3
  nx=6
  lx=0.6
  ny=6
  ly=0.6
  nz=6
  lz=0.6
  nmom=1
  nang=10
  ng=4
  epsi=1.0E-4
  iitm=5
  oitm=30
  timedep=0
  tf=1.0
  nsteps=1
  mat_opt=0
  src_opt=0
  scatp=0
  it_det=0
  fluxp=0
  fixup=1
  soloutp=1
  kplane=0
  popout=0
  swp_typ=0
/

and I compile with:

--- a/src/Makefile
+++ b/src/Makefile
@@ -7,13 +7,14 @@ FFLAG2 =
 DEFS =
 PP =
 
-MPI = yes
-OPENMP = yes
+MPI = no
+OPENMP = no
 
-FORTRAN = mpif90
+#FORTRAN = mpif90
 #FORTRAN = mpifort
 #FORTRAN = ftn
 #FORTRAN = mpiifort
+FORTRAN = gfortran
 
 TARGET = gsnap
 #TARGET = isnap

I run it with:

$ ./gsnap in1 out1        
          keyword Iteration Monitor
********************************************************************************
  Outer

it will just hang there, no other output produced, the file out1 is also empty. When I compile with MPI it seems to work, even just using one MPI rank (it finishes under 1s).

Is it supposed to run without MPI?

[zerr]

Change nthread to 1 in your input. Add the line multiswp=0. The former won't do anything, but it's consistent with what you're attempting to do. The latter... it's not immediately clear to me what I've done in the multiswp=1 scheduler that is not protected for serial case. Can either fix it there or force it to 0 at setup. Until I do that, this input mod will get you running.

[certik]

I applied the change:

--- a/src/in1
+++ b/src/in1
@@ -3,7 +3,8 @@
   npey=1
   npez=1
   ichunk=2
-  nthreads=2
+  nthreads=1
+  multiswp=0
   nnested=1
   ndimen=3
   nx=6

and ran as:

$ ./gsnap in1 out1
          keyword Iteration Monitor
********************************************************************************
  Outer
    1    Dfmxo= 3.5528E-01    No. Inners=   17
    2    Dfmxo= 1.7376E-01    No. Inners=   14
    3    Dfmxo= 8.6338E-03    No. Inners=    9
    4    Dfmxo= 3.4839E-04    No. Inners=    4

  No. Outers=   4    No. Inners=   44

********************************************************************************

 Success! Done in a SNAP!

and it works! Thanks. You can close this issue if you want.

[zerr]

I'll leave it open until it has a proper fix. It's probably broken in the production app, too.

Thanks for spotting this.

[zerr]

I don't see what exactly it is that is unhappy. But the simple fix is to force the change to multiswp=0 in the code. Done in latest commits to master and called version 1.11.

[certik]

Fixed in 39c24cc.